FREE-OPERANT AVOIDANCE Or; riME-OUT FROM }ESPONSE-lN;.)EpFNDENT FOOD PRESENTATION BY PIGEONS PECKING BY GREGORY GALBICKA A DISSERTATION PRESENTED TO Hit GRADUATE COUNCII OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 1901 To all nineteenth-century scientists, living or dead --magnetism notwithstanding-- ACKNOWLEDGEMENTS The verbal behavior which follows is, in a very real sense, not my own. Rather, it is the culmination of interactions with a verbal community which, particularly during the past seven years, has progressively shaped that verbal behavior. I would hope that this influence is clear enough in the behav- ior itself, such that others will call it "their own." Should the contingencies responsible for this behavior have been less than exact, however, I would like to formalize some of them, and in that way express my gratitude. First, the the members of the supervisory committee: To Marc N. Branch, for his guidance and support during the past four years, which, while substantial, was never totally complete, lest my behavior become rule-governed and echoic. To Edward F. Malagodi, for providing an integra- tive intraverbal repertoire found in no other single person, as well as sound advice. To Henry S. Pennypacker, most responsible for the development of a minimal behavioral repertoire from which extensions were later formed, for not pro- viding autoclitics until they were rnanded, thus strength- ening my own. iii IV To Robert J. Waldbillig, for providing additional "inside information." May we indeed by more closly al- igned in the future. And to John A. Cornell, whose central tendancy was always to understand this vast amount of verbiage. Next, to my parents, Joseph A. and Dorothy M. Galbicka, and other members of my family, as well as to Janet Siwy, for supporting and nuturing my conviction in a natural science of behavior more strongly than they may imagine. To the associated menbers of the Main Branch Lab, for tech- nical as well as intellectual support. To the Mew Wave Behaviorists, for providing a verbal commun- ity which did not severely punish novel verbal statements at odds with the prevailing contingencies, while heavily reinforcing oc- casional ones that were not. To the other faculty and students (graduate and undergraduate) associated with the Experimental Analysis of Behavior at Fort Skinner, for accepting and, I am afraid, occasionally reinforcing certain behavioral eccentricities. To Janie Partin, who independently acquired an intraverbal repertoire comparable to my own, for occasionally telling me what I should be saying. And finally, to John T. McArthur and Ray A. Preston, without whom I would never have "ventured so far from home," intellectually or physically. To all these the Tall Kid says "Thanks," hoping that my behavior in the future will be such that they will accept the recognition they deserve. TABLE OF CONTENTS ACKNOWLEDGEMENTS LIST OF TA3llS LIST OF FIGURES ABSTRACT GENERAL OVERVIEW CHAPTER I NEGATIVE RINFORCEMENT. I: PROCEDURES Deletion Procedures .... Delay Procedures .... Stimulus Modification Procedures II NEGATIVE REINFORCEMENT. II: CONTROLLING VARIABLES Contiguous vs_. Consequent Control Two-Factor Theories One-Factor Theories III INTRODUCTION TO THE PRESENT EXPERIMENTS IV EXPERIMENT I Method Results Discussion V EXPERIMENT II Method Results Discussion VI EXPERIMENT III Method Results Discussion VII GENERAL DISCUSSION .... APPENDIX DAILY SESSION DATA FROM EXPERIMENT II REFERENCES BIOGRAPHICAL SKETCH v PAGE i i i vi vii viii 1 4 4 11 18 23 23 25 33 41 50 51 56 67 77 80 81 91 93 96 107 122 131 133 145 LIST OF TABLES TABLE PAGE i List of conditions end summary measures for each subject during Experiment I 55 2 List of conditions and summary measures for each subject during Experiment II 82 3 List of conditions end summary measures for each subject during Experiment III , . . 95 VI LIST OF FIGURES IGURE PAGE 1 Response rates during time -in for each subject as a function of the RT interval 59 2 Numbers oF time-outs delivered to each subject as a function, of the RT interval 61 3 Representative cumulative records for each subject under the different RT intervals " 4 Relative frequency and conditional probability distributions for IRTs in fifths of the RT interval .... 66 b Cumulative records depicting transistions in key pecking of P-6441 between different RT intervals ... 69 6 Daily session response rates for each subject under the delay and yoked-VF contingencies 84 7 Cumulative records from selected sessions under the delay-contingency and under the corresponding yoked-VT session 87 8 ResDonse rates on the delay-key during time-in for P-7820 and P-6441 as a function of the RT interval 100 9 Representative cumulative records for P-7820 and P-6441 under the RT intervals of the two-key procedure 104 10 Numbers of time-outs delivered to P-7820 and P-6441 under the two-key procedure as a function of the RT interval 106 11 Relative frequency and conditional probability distributions of I^Ts in fifths of the RT interval under the two-key procedure for P-7820 and P-6441 109 vn Abstract of Dissertation Presented to the Graduate Council of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy FREE-OPERANT AVOIDANCE OF TIME-OUT FROM RESPONSE-INDEPENDENT FOOD PRESENTATION BY PIGEONS PECKING A KEY By Gregory Galbicka August, 1981 Chairman: Marc N. Branch Major Department: Psychology The present experiments examined the behavior of food-deprived pigeons pecking a small translucent disc ("key"). Food was occasion- ally presented independently of responding, except during signalled "time-out" periods, during which food was never presented. Key peck- ing during "time-in" postponed the next time-out according to a free- operant avoidance paradigm. Successive time-outs followed one an- other at 5-sec intervals (i.e., the time-out--time-out interval=5 sec) unless a response occurred during time-in, in which case the next time-out occurred x sec after the last response, where x^ was the length of the response--time-out interval. During Experiment I, stimuli correlated with time-in and time- out were projected on the key. Lengthening the response--time-out interval while maintaining a constant time-out--time-out interval viii progressively decreased response rates cluing time-in for all sub- jects . During Experiment II, the importance of the delay contingency in maintaining the key pecking observed was examined by presenting time-outs response-independently at variable intervals matched to ones obtained under a preceeding free-operant avoidance condition. Response rates for all subjects decre:~ed when the delay contingency was suspended in this manner. The independent contributions of responding maintained by time- out-postponement and responding elicited by the time-in and time-out stimuli were examined with a two-key procedure during Experiment III. Responses to a continuously illuminated "delay" key during time-in postponed time-out, signalled by stimuli projected on a separate "signal" key. Response rates on the delay key during time-in for two subjects decreased as the response--time-out interval was length- ened. Responding on the signal key was unsystematically related to the response—time-out interval, and generally occurred at very low rates. The third subject responded on the delay and signal keys at comparable rates, and response rates on the delay key during time- in were unaffected by changes in the response--time-out interval. Thus., free-operant time-out-postponernent may control key peck- ing in the relative absence of elicited pecking, but elicited re- sponding may contribute; to the behavior observed. GENERAL OVERVIEW The analysis of operant behavior (i.e., behavior modified by its consequences) may be partitioned into four broad classes, de- pending on whether increases or decreases in some characteristic property of a consequent stimulus are programmed as response con- sequences, and the effect of such consequences on the subsequent frequency of said response. (Morse and Kelleher (1977) present a classification scheme similar to the one here but emphasize con- sequent stimulus presentation or termination, respectively, rather than increases or decreases in some aspect of the stimulus.) In- creases in the frequency of a response vi_a response-contingent in- creases in some characteristic (e.g., frequency, magnitude, dura- tion, etc.) of a consequent stimulus are generally termed instances of "positive reinforcement." Increases in response frequency pro- duced in this manner are distinguished from increases produced via response-contingent decreases in consequent ("aversive") stimula- tion, which are termed "negative reinforcement." The common use of the term "reinforcement" highlights the increases in response rate observed with both manipulations, regardless of whether re- sponses increase ("positive") or decrease ("negative") some aspect of consequent stimulation. The analysis of these two types of con- trol has developed simultaneously and for the most part independently. 1 2 However, a number of parallels exist in both the development of pro- cedures and interpretations (see Hineline (1977) for a recent treat- ment of these similarities). The remaining tv/o classes of analysis are those in which response frequency decreases following a history of response-contingent stimulation ("punishment"), and may be simi- larly classed as "positive" or "negative." (The present paper is concerned primarily with reinforcement operations and in particular negative reinforcement, and as such punishment will subsequently be discussed only occasionally.) What follows is a review of the study of negative reinforcement, first with respect to the procedures that have been employed and second in terms of the controlling variables suggested as necessary for the acquisition and maintenance of behavior under this type of aversive control. The majority of the data to be reviewed involve the behavior of rats, and in particular rats depressing a small, generally rectangular piece of metal protruding perpendicularly from one wall of an experimental chamber (i.e., "bar" or "lever" press- ing). This subject/response combination has so frequently been used in the analysis of negative reinforcement contingencies that exceptions need be, and have been, noted. The research conducted in the present studies represents one such exception and involves the modification of a frequently used procedure in the analysis of negative reinforcement. Under this modified procedure, food-deprived pigeons pecked a small translucent disc ("key"), and each peck post- poned for a fixed period the occurrence of a signalled period of time-out from response-independent food presentation. 3 One final note is in order before proceeding. The response most often studied under negative reinforcement contingencies has not always been the lever press. Prior to the mid-1950 's, a num- ber of investigators (e.g., Mowrer & Lamoreaux, 1942) examined the effects of negative reinforcement contingencies on running in a "shuttle-box." This apparatus consists of a rectangular enclosure partitioned along the major axis into "sides" and some means of de- termining which side the subject occupies at different points in time. The response defined by such an apparatus is movement to the opposite side. Results from these experiments have, not imperti- nently, largely been excluded from the review. Running in a shut- tle-box is affected by negative reinforcement contingencies in ways comparable to effects noted when bar pressing is the measured re- sponse. Since studies involving the latter are generally more con- temporary, they have taken precedence over the former in the pre- sent review. Where important, however, either for historical rea- sons or in discussing response topography per se, results from ex- periments involving "shuttling" have been included. CHAPTER I NEGATIVE REINFORCEMENT. I: PROCEDURES The procedures most often employed in the study of the main- tenance of behavior by aversive stimuli may be broadly classified in terms of whether a response is experimentally programmed to delete, delay, or otherwise modify some characteristic property of the aversive stimulus. While the functional effects of these pro- cedures may not be so clearly discernible, classification in terms of the experimentally programmed effects of responses provides a convenient, if arbitrary, means of distinction. Deletion Procedures Aversive events may be presented continuously or intermittently. When a response terminates a continuously present aversive event for some period of time, an escape paradigm is defined. The ear- liest studies involving such procedures were conducted by invesi- gators interested in respondent conditioning (e.g., Bechterev, 1913; Pavlov, 1927). Bechterev (1913), using electric shock delivered through a panel on which a dog's foot rested, reliably observed flexion following the onset of shock. Since in many cases flexion resulted in the termination of shock, it is difficult to discern whether the response was "elicited" by the presentation of the 4 5 "unconditional stimulus" or was maintained as an effective escape response through response-contingent termination of shock. Under the procedure described above, a single response resulted in termination of toe aversive stimulus. Dinsmoor and his colleagues (e.g., Dinsmoor, 1968; Dinsmoor & Winograd, 1958) developed a pro- cedure under which responses terminated shock according to a vari- able-interval (VI) schedule. Under this procedure, in the presence of continuous electric shock, the first response after some average interval of time produced a fixed period of shock-free time. They reported that rates of bar pressing in rats were directly related to the intensity of shock delivered (Dinsmoor & Winograd, 1958) and that responding maintained by escape from continuous shock was simi- lar to responding maintained by a comparable VI schedule of dele- tion of frequent, irregularly-spaced brief shocks (Dinsmoor, 1968). (Whether this latter procedure should be termed "escape" is debat- able, since shock was not continuously present. The distinction may be of little use, however, if the behavior maintained is simi- lar. Rather, it may be more fruitful, as Hineline (1977) suggested, to consider both procedures as shock-deletion procedures which vary only with respect to the background density of aversive stimulation.) Deletion procedures involving more intermittent shock include both free-operant procedures (where the opportunity to respond is continuously present) and discrete-trials procedures (where response opportunity is restricted). Sidman (1966) maintained bar pressing in rats under a procedure he termed "fixed-cycle avoidance" where 6 a brief shock was scheduled to occur every t sec. A single response anytime during the inter-shock-interval cancelled the delivery of shock at the eod of that cycle. DeVilliers (1972, 1974) modified this procedure such that shocks were scheduled to occur at variable rather than fixed intervals ("VI shock deletion"). Rats' bar press- ing rates under this latter procedure were linearly related to the number of shocks deleted (deVilliers, 1974). When an independent VI shock deletion schedule was programmed simultaneously for each cf two responses, relative response rates and relative rates of shock deletion were also linearly related (Logue and deVilliers, 1978). This latter relationship is similar to those obtained under analo- gous procedures involving positive reinforcement (See deVilliers (1977) for a recent review of this literature). Additionally, de- Villiers (1974) observed both positive and negative behavioral con- trast, (cf. Reynolds, 1961; Schwartz & Gamzu, 1977) with rats lever pressing under a multiple schedule (in which two or more schedules, or "componenents," alternate in succession, each in the presence of a unique exteroceptive stimulus) with VI shock deletion schedules in the two components. He also noted that these contrast effects increased with decreases in component duration, an effect similar to that obtained under schedules of positive reinforcement (e.g., Shirnp & Wheatley, 1971; Todorov, 1972). Herrnstein and Hineline (1966) developed a procedure under which shocks could be delivered at random intervals according to one of two constant-probability distributions of inter-shock-intervals. 7 One distribution, the "post-shock" distribution, was effective if a response had not occurred since the last delivered shock. A single response deleted shocks scheduled by this distribution, and the shock delivery was subsequently controlled by the second ("post-response") distribution until a shock was delivered according to that distribu- tion. Following this shock delivery, control reverted back to the post-s'nock distribution. Unlike the previously described shock- deletion procedures, not all shocks could be deleted by responding; responding deleted only those shocks scheduled according to the post- shock distribution. Responding was maintained under this procedure whenever the frequency of shock programmed by the post-response dis- tribution was less than the frequency scheduled by the post-shock distribution, even with shock frequencies as close as six and nine per rain, respectively, scheduled by the post-response and post-shock distributions. A classification system originally developed by Schoenfeld and Cole (1972) to describe schedules of positive reinforcement can be extended to describe certain other free-operant negative reinforce- ment procedures. The system involves continuously repeating cycles T sec in duration. These cycles are further divided into subcycles denoted t and t . The first response during t_ deletes shock scheduled to occur at the end of T. All other responses are ineffec- tive. Hurwitz and Millenson (1961) programmed cycles of constant A [) duration comprised of a t and following t period, and manipulated the relative amount of time occupied by i in X- With increases in the relative duration of It , response rates first increased then de- creased in a manner similar to relations obtained by Hearst (1960) with comparable manipulations under an analogous schedule of response- contingent food presentation. Sidman (!962a_) obtained results simi- lar to Hurwitz and Millenson's when t_ occurred at the end of each cycle; however, when t was shifted towards the middle of T (such n n that t periods occurred both prior to and after t ), responding ceased. Kadden, Schoenfeld and Snappar (1974) independently manipu- lated the probabilities of shock given a response during t and given no response, and found that bar pressing of rats was maintained when- ever the former was less than the latter. They also noted that re- sponse rates were positively accelerated across T when t occupied a large portion of T, provided the probability of shock given a response in tD was greater than 0.0 but less than that which suppressed respond- ing. Responding under the free-operant procedures described thus far deletes only the scheduled occurrence of brief, intermittent aversive stimulus presentations. Responding may also be maintained when it terminates a stimulus correlated with aversive stimulation, as well as deleting the aversive stimulus itself. Hake and Campbell (1972) produced positively accelerated patterns of lever pressing in squirrel monkeys resonding under a fixed-interval schedule of stimulus-shock complex termination. In the presence of a unique exteroceptive stimulus, brief shocks were delivered every 30 sec, and the first response after 3 min terminated for 3 min the stimulus correlated with shock delivery and interrupted the periodic delivery of shock. 9 Byrd (1977), also using squirrel monkeys, maintained patterns of lever pressing characterized by a pause followed by an abrupt tran- sition to a high rate under a procedure similar to Hake and Cembali's except that, a fixed number of responses (fixed-ratio) was required for termination, and Kelleher and Morse (1964) maintained schedule appropriate responding in squirrel monkeys when fixed-interval and fixed-ratio schedules of stimulus-shock complex termination alter- nated in the presence of distinctive stimuli. Krasnecor, Brady and Findley (1971) examined various pairs of ratio requirements under a slightly different stimulus-shock complex termination procedure. Sessions consisted of repeating 90 sec cycles. The first 30 sec of each cycle was signalled by the illumination of a blue light (S-,), unless the subjects (rhesus monkeys) emitted a fixed number of lever presses. Completion of the ratio requirement terminated S-, and produced a "blackout" for the remainder of the 90 sec cycle. If the ratio requirement was not met within the first 30 sec, the blue light was replaced by a green one (Sp) for 30 sec, again unless a fixed number of responses (not necessarily the same » as that required in the presence of S-,) was emitted within 30 sec. Completion of the ratio requirement in So likewise produced a black- out for the remainder of that cycle. If neither requirement was met, S2 was followed immediately by illumination of a red light for 3 sec, during which 3 brief shocks were delivered at one-sec intervals, then by a 27-sec blackout. Subjects almost invariably completed one of the two ratio requirements and, hence, few shocks were delivered. When the ratio requirements in the presence of S-, and S2 were identical, 10 responding was slightly "biased" towards S2 (i.e., slightly more ratios were completed during Sn than during S-,). When the requirement in one component was varied while maintaining the requirement in the other component constant at 30, the frequency with which ratios were completed during the varied component was inversely related to the ratio value but was directly related to this value in the constant component. Studies of discrete-trials deletion procedures are less numerous than the above described free-operant ones. Hineline and Herrnstein (1970) used a discrete-trials procedure they termed "fixed-cycle deletion" to maintain bar pressing in rats. Twenty-sec trials ended with presentation of a brief shock unless a single response occurred during the trial, in which case the lever immediately retracted for the remainder of the trial and shock presentation at the end of that trial was deleted. Nef finger and Gibbon (1975) and Flye and Gibbon (1979) extended Gibbon, Berryman and Thompson's (1974) ration of "contingency spaces" to the analysis of aversive control by negative reinforcement with "partial avoidance" procedures. Like Hineline and Herrnstein's procedure, brief shocks were scheduled to occur at the end of each 20-sec trial unless a response occurred. As in fixed-cycle deletion procedures, responses were followed by retrac- tion of the lever- or produced some other exteroceptive stimulus change. However, unlike fixed-cycle deletion procedures, where the probability of shock given a response is always 0.00 and 1.00 given no response, partial avoidance procedures allow the probability of shock delivery 11 given a response to he varied independently of the probability of shock niven no response. Bar pressing in rats typically was maintained whenever the probability of shock given a response was less than that given no re- sponse. (A few subjects responded when the two probabilities were equal, however this responding was characteristically short-latency responses, and may have been either shock-elicited or -induced.) Delay Procedures Unlike the deletion procedures, delay (or postponement) procedures do not cancel discrete occurrences of aversive events, but rather postpone them for some period of time. (Again, the distinction is between the experi- mentally programmed effects of a response, not possible functional ones.) As with deletion procedures, delay procedures vary with respect to such para- meters as continuous y±. intermittent aversive stimulation, fixed vs. variable delays, free-operant yjs_. discrete-trials procedures, etc. Probably the most frequently used delay procedure is "free-operant avoidance" (Sidman, 1953). Typically, in the absence of responding, brief inescapable shocks occur at fixed intervals, specified by the "shock-shock" (SS) interval. Responses delay the next shock for some fixed period of time, termed the response-shock (RS) interval. Delays do not cumulate; that is, shock al- ways occurs x sec (specified by the RS interval) after the most recent response. Sidman studied bar' pressing of rats which resulted in shock-postponement un- der this procedure. However, a variety of species, responses and aversive events have been used with surprising generality of effects. Rats bar press under control of noise-postponement (Knutson & Bailey, 1974), postponement 12 of time-out from response-independent food presentation (D 'Andrea, 1971) or food presentations (Smith ft Clark, 1972), and have "shuttled" (e.g., Harman & Hineline, in Hineline, 1977; Lib by & Church, 1974) or run in a wheel (Weisman ft Litner, 1959) when such responses de- layed presentation of brief electric shocks. Dogs have acquired panel press (e.g., Rescorla, 1969) or shuttle (Rescorla, 1968) re- sponses under shock- postponement procedures. Key pecking (e.g., Ferrari, Todorov ft Graeff, 1973; Todorov, Ferrari & de Souza, 1974) or treadle pressing (e.g., Dinsmoor ft Sears, 1973; Foree S LoLordo, 1970; Jowaisas, 1977; Rilling & Budnick, 1975; Smith ft Keller, 1970) of pigeons have been comparably controlled under similar shock- postponement procedures, and key pecking which results in postpone- ment of time-out from response-independent food presentation (Thomas, 1965^, 1965bJ has also been examined. Numerous studies have reported free-operant avoidance in rhesus and squirrel monkeys (including Clark and Smith's (1977) of food-postponement), and humans have turned levers when such responses postponed time-out from response-independent money presentations (e.g., Baron & Galazio, 1976; Baron & Kaufman, 1966). Reliable acquisition of free-operant avoidance depends on a rela- tively short SS interval with respect to the RS interval (Leaf, 1965; Sidman, 1962; but, cf. Clark ft Hull, 1966) although the absolute values required for acquisition may vary depending on the response employed (sea, for example, Harman ft Hineline, in Hineline, 1977). Responding is also (possibly even more) reliably engendered when the basic proce- dure is modified to provide variable SS (Bolles ft Popp, 1964), RS 13 (Sidman & Boren, 1957_a) or SS and RS (Hineline, 1977) intervals. Patterns of responding engendered under free-operant avoidance pro- cedures consist of fairly constant overall rates of responding, with transient increases in response rate ("bursts") immediately after delivery of the aversive stimulus (e.g., Boren, 1961; Ellen & Wilson, 1964). These increases may be due to responding elicited by aversive stimulus presentation (e.g., see Hutchinson, 1977) or maintained by adventitious escape contingencies. Boren (1961) pro- vided suggestive evidence for the latter notion with a free-operant avoidance paradigm involving two levers, one effective only during RS and one only during SS intervals, respectively. With an SS intervals (a delay analog of escape), bursting occurred predomi- nantly during RS intervals, but occurred more frequently on the SS-interval lever, the one associated with shock termination. Although overall rates of responding are generally fairly con- stant under free-operant avoidance procedures, the distribution of times between successive responses, or interresponse-times (IRTs), has on occasion been reported to be non-random. Specifically, the conditional probability of an IRT (i.e., the probability of an IRT of length t sec given at least that amount of time has elapsed since the preceding response) has been reported to increase with increas- ingly long IRFs for rats shuttling (e.g., Libby & Church, 1974) or bar pressing (Sidiiian, 1966) and pigeons key pecking (Jowaisas, 1977) under free-operant shock-postponement procedures. This type of tem- poral control need not develop, however, prior to or concurrent with 14 the development of stable performance in terms of overall response rate, and may appear in some subjects only after extended exposure under the procedure (see, for example, Sidman, 1966, particularly pp. 4G4. ff.). Overall rates of responding maintained by free-operant avoidance procedures depend on the values of both the SS and RS intervals. Re- sponse rate generally increases rapidly to a maximum as the RS inter- val is increased to a value equal to or slightly less than the SS interval, then declines exponentially with longer RS-interval values (e.g., Clark & Hull, 1966; Klein & Rilling, 1972; Sidman 1953; Thomas, 1965a/, Tcdorov, Ferrari & de Souza, 1974). Verhave (1959) obtained similar functions, with the exception of higher absolute response rates than those reported by Sidman (1953), when the number of re- sponses required to initiate a new RS interval was raised from the traditional single response to eight responses. Additionally, re- sponse rates are directly related to both the intensity (Boren & Sidman, 1959; Klein & Rilling, 1972; Leander, 1973) and duration (Leander, 1973) of shock presented. The standard free-operant avoidance procedure may be modified in a number of ways other than the ones cited above. One modification, termed "discriminatx'd free-operant avoidance" (e.g., Sidman, 1955, 1957, Sidman & Boren, 1957b, 1957c), involves the interpolation of exteroceptive stimuli differentially correlated with the delivery of shock. As these procedures played an important role in the develop- ment of theoretical accounts of aversive control, detailed discussion 15 will be reserved until later. Other variations of the basic proce- dure have been examined. Boren and Sidman (1957a_) modified the stan- dard free-operant avoidance paradigm to examine the effects of deliver- ing only a percentage of shocks actually scheduled. Response rates were generally unaffected across a wide range of values until the probability dropped to approximately 0.05. These results are compar- able to those obtained by Neffinger and Gibbon (1975) and Flye and Gibbon (1979) with their discrete-trials partial avoidance deletion procedure, where responding was maintained at substantial levels when as many as 95% of shocks scheduled to occur on trials with a response were cancelled. Sidman (1962b_) and Field and Boren (1963) modified the paradigm to produce an "adjusting avoidance" procedure. Under the standard free-operant avoidance procedure, shock is postponed to occur x_ sec after the last response, where x is the value of the RS interval. Under adjusting avoidance schedules, each response postpones shock for x sec, and the delay cumulates across successive responses to some maximum value. Thus, with an RS interval =15 sec, two responses spaced 8 sec apart would result in shock presentation being post- poned until 23 sec after the first response under standard free- operant avoidance, but until 30 sec after the first response under an adjusting schedule. Responding maintained under adjusting avoid- ance schedules usually results in shock being greatly postponed, and the degree to which it is postponed is decreased with the addition of stimuli correlated with the time to shock presentation (Field & 16 Boron, 1953). Sidman (1966) pointed out another interesting dif- ference between standard free-operand and adjusting avoidance pro- cedures by noting that adjusting schedules do not provide differen- tial consequences for spaced-responding. Under free-operant avoid- ance "efficient'1 responding (measured in terms of the number of responses per shock presentation) should be characterized by fairly widely-spaced responses since a response occurring soon after a response does not provide as much additional delay as one occurring relatively later. Indeed, as mentioned above, responding under free- operant avoidance procedures is typically characterized by an in- crease in the conditional probability of a response with increasing post-response time. Adjusting avoidance procedures do not provide differential delay of aversive stimulation following spaced responses, since each response adds a specified delay regardless of where it occurs in the RS interval. As such, one might not expect to see the increase in response probability with increasing post-response time. Sidman (1962b) reported exactly that; conditional probabilities of interresponse-times remained relatively constant or decreased at longer interresponse-times under such a procedure. The last free-operant delay procedure to be discussed is that described by Sidman (1966) termed "fixed-interval avoidance" (more for the patterns of behavior produced, it seems, then for a specifi- cation of fixed periods of time between successive shock presentations) A D Sidman modified the deletion procedures which specify t and t periods during which responding is ineffective or deletes shock scheduled to occur at the end of tD, respectively. Responses during 17 t under fixed-interval avoidance do not cancel the presentation of shock but rather prolongs the t period (and, thus, delay shock) for some fixed period of time. Patterns of responding engendered under this procedure were typically positively accelerated, more so than those reported by Kadden, Schoenfeld and Snapper (1974) under stan- dard deletion procedures, possibly because each cycle under fixed- interval avoidance begins with shock presentation, which could act A as a discriminative stimulus signalling the beginning of t , thus controlling a decreased rate of responding early in each cycle. Hineline (1970) developed a discrete-trials procedure in which one shock was delivered during every 20 sec trial. Each trial began with insertion of a retractable lever into the chamber and, if no re- sponse occurred within 8 sec, a brief shock was delivered on the eighth sec. Two sec later the lever was retracted for 10 sec, and then reinserted to begin the next trial. If a response occurred prior to the delivery of shock, the lever immediately retracted, and shock delivery was delayed until 18 sec into the trial. Responding was reliably maintained under this procedure. Benodict (1975) modified this procedure to differentiate latencies to a response. With dif- ferent groups of rats, the delay to shock was either directly or in- versely related to response latency. Thus, for the "long-latency- long-delay" group, each sec in the latency to a response from trial onset added a sec to the delay to shock achieved by a response, while for the "short-latency-long-delay" group each additional sec in the response latency subtracted a sec from the delay. Response latencies for the first group were generally longer than those for the second. 18 Gardner and Lewis (1976, 1977) and Lewis, Gardner and Hutton (1976) developed a discrete-trials procedure to incorporate multiple delayed shock presentations. In the absence of responding, brief shocks were delivered (in the presence of a distinctive stimulus) at random intervals averaging 30 sec. A single response in the presence of this stimulus initiated a 3-min alternate condition correlated with a second stimulus, during which six shocks were delivered one sec apart, beginning either 10, 88 or 165 sec (under different exper- imental phases) after the response. (Further responses during the alternate condition had no scheduled consequences.) The percentage of time rats spent in the alternate condition was directly related to the delay to the first shock following a bar press which initiated the alternate condition, and substantial responding was maintained when a response delayed the presentation of as many as 12 similarly- spaced shocks for 105 sec. Similar results were also obtained with pigeons key pecking under a similar shock-delay procedure (Gardner & Lewis, 1977). Stimulus Modification Procedures The third and final class of aversive control paradigm includes those procedures which provide response-dependent modulation of some physical property of the aversive stimulus. While all deletion pro- cedures may be considered to modify either the duration and/or the intensity of aversive stimulation, only those procedures which do not concomitantly decrease the frequency or otherwise change the temporal 19 distribution of aversive events in time will be considered in this category. Weiss arid Laties (1959, 1963) modified the traditional escape, paradigm by programming response-contingent intensity-reduction, rather than termination, of a continuously present shock which in- creased in intensity every t sec without a response. This procedure has become known as "shock-titration" or "fractional escape." Response rates under such procedures are inversely related to the time between successive increments in shock intensity in the absence of responding, and decreases in the value of this parameter, as well as increasing the number of responses required for a decrement in shock intensity, results in an increase in the median intensity of shock delivered (Wiess & Laties, 1959). Powell and Peck (1969) reported that acquisition of lever pressing by rats was more reliable under a procedure where each lever press reduced for 20 sec the inten- sity of shocks delivered every five sec than with a standard free- operant avoidance procedure with an SS interval =5 sec and an RS interval=20 sec. Bersh and Alloy (1978) maintained lever pressing under IRT S- OJ ill - — £Z Cf- o 0) <- 5- r— m 4- Ol CJ CL 00 •o CI. rrf (!) 3 .£} .- — , +J IT o CU O OJ HI -£= +J ( 1 h- n. OJ +J o oo CU +-> • 00 to cu -l-> QJ 5- -C S- s- 0J re s- c o to s- 4-> 0J CU O o E -C U 4- +■> •i— -m a) if- 4-> o; T3 i— cn E s- 3 +J O T- Cf- -O ',', T- TD O +-> CI) OO 0) 1 IDE -a to CU -t-> (B CEC0J OJ O •!- cu -C t- Q-+-> to -l-> to cu a; a) cs-x: E s- c a.4-» •r- O +-> JZ i- -o -Q u 3 o ra -a o "a • -a cu f- CU r— s_ ■a •*-> tc o x: cu cu ra > o •4-> +-> +-> E S- cu •i- cj o t- cu S_ 5 cu c x +-> i— cu o c c~ • >,<+- -a i. -r- CJ r— CJ _ Q. r3 >— -a J= D-h- rs ^ to or CJ oo 1J- Q) C ■i- rs ----- >>.£= i — l 4-> v: 4-> i— o S- C 0J ra CJT3 GJ in CJ > c > o to rrj OJ r— +-> -a — -• o ro re 0J « Cx. ir> 5- 4-> "O <^ a. cu cu to ai CU CJ oo 3: O S- -M +J C O E cu c: tO O I — > Cu +-> 'r- a co gj ra i — I— cj cu -c x: cu or a. s- +-> 4-> -a A L \ \ A / \ r /\ Y CM t £ \ f E,H 009 Figure 4. Relative frequency (filled circles) and con- ditional probability (open circles) distributions for IRTs in fifths of the RT interval. Points and vertical bars represent means and ranges, respectively, of values observed durino the last 5 sessions at each RT interval. (Due to an apparatus mal- function, data are only available for some RT intervals.) Ranges of points without vertical bars are contained within the point.' 65 R-T=5sec R-T=!Osec R-T=20sec R-T=40s3c Q D O to o t- o 0 X >- o h- _] CO o < UJ m tr o u_ tr. _j Q_ UJ d t" 80- 60- 40 20 60H 40 20- 100- 80- 60 40H 20 O t / W* P-7820 rf i i i i i i i i i i i i i i i i i i P-9275 i i i i i — i i i i r i • i i " t P-644! ill! TUH TTTII TT1 4 5 ,2345 (l-sec bins) (2-sec bins) (4-sec bins) (8-sec bins) INTERRESPONSE-TIME BIN 67 IRTs/Op at all PT intervals, although the differences in condi- tional probabilities between IRT classes were small at RT interval3 10 sec. Interresponse-time distributions of P-9275 showed little temporal control ever responding by RT interval at any RT inter- val length, whereas distributions for P-6441 showed temporal con- trol over IRTs at RT interval =5 sec but not 20 sec. The development of steady-state performance occasionally re- quired a great deal of exposure to the different RT interval values, due more to short-term oscillations in response rate than to grad- ual transitions between experimental phases. Indeed, initial tran- sitions were generally very rapid. Data depicting such transi- tions for P-6441, a representative subject, are presented in Fig. 5 in the form of cumulative response records. On the left are cumu- lative records obtained during the last day of exposure to one RT interval, and on the right those obtained under the first day of exposure to the subsequent RT interval. Comparison of records on the right with those immediately below it on the left (the first and last day of exposure to a specific RT interval, respectively) reveals that response rates approximating those obtained after extended exposure were generally obtained by the last third of the first session under the new RT interval value. Discussion Key pecking was reliably and quickly engendered in all sub- jects under the present procedure. It should be noted that the Figure 5. Cumulative records depicting trans istions in key pecking of P-6441 between different RT intervals. Records on the left show responding during the last session at a specific RT interval value, those on the right during the first session of the subsequent value. The first and last day of exposure to a particular RT interval is shown, respectively, in a record on the right and the one immediately beneath it on the left. Recording characteristics are the same as those for Fig. 3. 69 rt-T*20-*«c >»-R-T=IOsK R-T«!0 ssc^- R-T» 40 sac R-T=5secs-~-R-T=20 -,sc 30 min 70 procedure used to establish key pecking in two of the subjects (P-9275 and P-6441) was merely a modification of the procedure used by Brown and Jenkins (1968) to "autoshape" key pecking. Un- der their procedure, one stimulus was reliably followed after 8 sec by the presentation of food, while food was never presented in the presence of a second stimulus. Under the present procedure, the time-in and time-out stimuli, respectively, defined a similar- differential relation with respect to food delivery (see, e.g., Gamzu & Williams, 1971, 1973), with the exception that food pre- sentation could occur anytime during the presence of the former stimulus, not just following it. The linear relation obtained in the present study between time-in response rate and RT interval (when plotted on double- log axes) was comparable to ones reported by Thomas (1965aJ, who used a similar procedure, and by others using analagous shock- postponement procedures (e.g., Clark & Hull, 1966; Klein & Ril- ling, 1972; Sidman, 1953; Todorov, Ferrari & de Souza, 1974), suggesting that responding was maintained in similar ways. Whether response rates would have decreased at even shorter RT intervals, as it does in other species (e.g., Sidman, 1953) can- not be readily determined, since RT intervals shorter than the TT interval were not examined. However, P-9275's deviation from the linear function towards a lower response rate at RT interval = 5 sec may be indicative of that kind of process. Although the functions obtained were similar, the absolute response rates observed in the present study were much greater 71 than those obtained by Thomas (1955a). Response rates observed by Thomas ranged from approximately 0.4-3.6 R/min, but from approxi- mately 5.0-40.0 R/min under the present procedure. Given the num- ber of procedural differences between the two studies, it is im- possible to interpret these differences. However, differences in time-out duration and/or rate of food presentation, while producing different absolute response rates, did not substantially change the form of the functions obtained here relating response rate during time- in to RT interval from that observed by Thomas. This suggests that the "behavioral process" represented by this func- tion may be largely independent of variables other than the length of response-contingent delay of time-out. One procedural feature seemed to enhance performance greatly during initial pilot studies. During pilot experiments, as in Thomas's study, the time-in and time-out stimuli were signalled originally only by colors of the keylight, with the house! ight remaining continuously illuminated. Under this pilot procedure, presentation of the time-out stimulus was followed typically by the subject turning away from the stimulus and engaging in other behavior (e.g., pecking the floor, preening, etc.). As such, the subject would typically be facing away from the response key when time-out ended. Often, the subsequent time-in period would e- iapse and another time-out ensue. A brief darkening of the house- light at time-out termination was therefore employed in an attempt to provide a discriminative stimulus which would be effective 72 regardless of the subject's orientation with respect to the re- sponse key. The addition of this stimulus resulted in rapid ter- mination of other ongoing behavior when time-in began and immedi- ate approach towards the response key, thus enhancing performance. The patterns of responding maintained under the present pro- cedure were also highly comparable to those reported for rats bar pressing under comparable shock-postponement procedures (e.g., Boren, 1961; Ellen & Wilson, 1964) with the exception of the ap- parent absence of a large warm-up effect (e.g., Hineline, 1978a_, 1978b; Sidman, 1966). If further analysis substantiates the lack of warm-up, it may lend credence to Hineline's (1978a) sugges- tion that such effects reflect habituation of non-operant behaviors evoked by aversive stimulation. It is possible that elicited key pecking directed at the stimulus signalling food delivery inter- acted with negatively-reinforced key pecking in ways functionally similar to the interactions suggested by Hineline. However, rather than "competing" with operant behavior as Hineline sug- gests it does under free-operant shock-postponement procedures, elicited behavior under the present procedure may have combined additively with negatively-reinforced key pecking since the food- correlated stimulus was located on the response key. Hence, re- sponse rates early in the session might be expected to be increased, rather than decreased early in the session, due to this transient additive influence. There are presently no data describing within- session changes in elicited pecking to either support or refute this interpretation. 73 The inconsistent development of temporal control over re- sponding by RT interval length (as evidenced by increasing con- ditional IRT probabilities with increase';, in IRT length) across subjects and RT intervals cannot at the present time be inter- preted with confidence. Sidman (195G) suggested that such con- trol may occasionally develop slowly, and that stable rates of responding may be maintained without concomitant evidence of tem- poral control by RT interval length. Although each RT interval was in effect for a comparatively large number of sessions during the present study, the number necessary for this type of control to develop (if it does reliably develop) is at the present time unknown. It is clear from the present results that such control did not develop rapidly. However, since RT intervals were changed during the present study without regard to the distribution of IRTs, it is possible that extended exposure to each value would have resulted in increased temporal control over responding. It may be of interest in this regard that P-7820 (who most consis- tently evidenced some degree of temporal control over responding) was generally exposed to each RT interval longer than the other subjects. In any event, it is clear that the vast majority of IRTs fell withing the range specified by the first bin in each dis- tribution. It has been suggested that certain topographical characteristics of key pecking may result in the transduction of extremely short (less than 0.8 sec) IRTs which do not appear 74 to be subject to control by positive reinforcement contingencies (e.g., Slough, 1966, Shimp, 1973). Whether this is the case here is difficult to ascertain given the relatively large class inter- vals used in the IRT analysis. Although the present results suggest comparability between free-operant avoidance of time-out and avoidance of other aver- sive events, other interpretations are possible. First, the absence of a delay between a key peck and subsequent presenta- tion of food may have led to the "superstitious" maintenance of key pecking. Although this claim cannot be refuted directly, it is difficult to see how decreases in the RT interval could pro- duce increases in the frequency of accidental correlations be- tween responses and food presentations necessary to account for the systematic increases in response rate observed at progres- sively shorter RT intervals. It might, in fact, be easier to argue the converse. That is, the frequency of spurious cor- relations might be expected to increase with increases in the amount of time-in time (and, hence, at longer RT intervals). However, it is possible that response rate increases initially produced by decreases in RT interval length may subsequently in- crease the probability of close contiguity or frequency of dif- ferential accidental correlations between responses and food presentations. These correlations may then further increase response rate, thus tending to overestimate the increase pro- duced by the postponement contingency alone. However, such 75 effects depend en the initial modification of behavior by the postponement contingency, and cannot, therefore, suggest that the avoidance contingencies were of little importance. A second alternative interpretation of the present results involves the role of elicited key pecking under procedures in- volving differential stimulus-reinforcer contingencies. As pre- viously discussed, food-deprived pigeons will peck at stimuli differentially correlated with the delivery of food. Addition- ally, the rate of pecking appears to increase as the duration of a signal differentially correlated with food presentation de- creases relative to the duration of stimuli signalling either the absence of food (e.g., Baldock, 1974; Terrace, Gibbon, Far- rell & Baldock, 1975) or a decreased frequency of food presen- tation (Spealman, 1976). Applied to the present situation, the relative duration of the time-in stimulus (signalling imminent food presentation) decreased with increases in the number of time- outs (signalling the absence of food) presented. Since the num- ber of time-outs delivered tended to increase with decreases in the RT interval (and thus the relative "time-in" time decreased), the increased rates of responding at shorter RT intervals might be ascribed solely to increases in the rate of elicited key peck- ing. Although the large differences noted in response rates un- der the different RT interval values in the presence of similar rates of time-out presentation (see Figs. 1 and 2, particularly data for P-7820 at RT interval =5 and 10 sec and for P-6441 at 76 RT interval-^ and 20 sec) argue against such an interpretation, it. might be argued that, while frequencies of time-out under the different conditions were comparable, the distributions of inter- time-out- intervals (times between successive time-out presenta- tions) may not have been, thus producing differences in the rate of elicited pecking. Data obtained in the second and third ex- periments suggest, however, that an interpretation based solely on elicited key pecking cannot account for the performance gen- erated under this procedure. CHAPTER V EXPERIMENT II Interpretation of the results of Experiment I solely in terms of elicited key pecking would suggest that the response-contingent postponement of time-out was of little importance in the mainte- nance of different rates of key pecking except in providing a changing number of time-out presentations. If this interpretation is correct, then presentation of similar distributions of time- out independently of responding should produce little change in the rates of key pecking maintained. Conversely, interpretations based on the negative reinforcement provided by response-contingent delay of aversive stimulation would suggest that removal of such a contingency (i.e., programming "extinction") would result in decreases in response rate. A number of extinction procedures have been used in the analy- sis of behavior maintained under free-operant avoidance procedures. The first consists simply of no longer presenting the aversive stimulus, and generally results in fairly rapid reductions in response rate (e.g., Boren & Sidman, 1957b_; Schnidman, 1953). Although the effects of this manipulation are similar to extinc- tion of positively reinforced behavior (where responding no longer results in the presentation of reinforcement), it has been argued 77 78 that such a manipulation decreases responding through behavioral mechanisms other than extinction C|ua extinction. Davenport, Coger and Spector (1970), for example, have argued that the removal of shock reduces response rates either by removing the "motivation" that usually increases the effectiveness of aversive-stimulus delay as a reinforcer (much as pre-session feeding decreases responding maintained by response-contingent food presentation), or by rein- forcing all responses equally, since all responses "delay" aver- sive stimulation for equal amounts of time. They suggest that a more "proper" extinction procedure would involve elimination of any response-contingent delay to the next aversive event, not elimination of the event itself, since the former, not the latter, presumably constitutes reinforcement under free-operant avoidance paradigms. Thus, for example, they would argue that, after train- ing under a free-operant shock-postponement procedure with an RS intervals sec and an SS intervals sec, extinction would involve presentation of shock every 5 sec, independent of responding. This procedure does generally decrease response rates (e.g., Davenport, Coger & Spector, 1970; Davenport & Olson, 1968) but also produces a more or less drastic change in the prevailing stimulus conditions, depending on the level of responding maintained originally under the postponement procedure. That is, for an animal reliably responding within the RS interval (and thus reliably delaying shock), the sudden presentation of shock ever 5 sec serves as a 79 highly discriminate change in the prevailing contingencies. Coulson, Coulson and Gardner (1070), recognizing this fact, have suggested a third procedure for the extinction of negatively reinforced beha- vior, involving the suspension of any response-contingent delay while maintaining comparable frequencies and distributions of response-independent aversive-event del ivery. This procedure is also effective in reducing response rates, however, responding generally decreases more slowly and does not cease altogether (Coulson, Coulson & Gardner, 1970; Smith, 1973). This last procedure is most relevant to the question of the role of elicited key pecking under the time-out delay procedure of Experiment I. To reiterate, key pecking maintained under the time-out-delay procedure should not be greatly affected by response- independent presentation of similar temporal distributions of time- outs if such responding is solely elicited by occasional presenta- tion of the time-in stimulus. If, however, key pecking under this procedure depends on response-contingent delay of time-out, remov- al of the delay contingency, even in the presence of continued oc- casional presentation of time-out, should reduce response rates. The present experiment examined responding maintained under such a procedure and provided data on the recoverability of the per- formance engendered during Experiment I. 80 Method Subjects and Apparatus The subjects and apparatus used were the same as in Experi- ment I . Procedure Directly following exposure to RT interval=5 sec under Experi- ment I, each subject was returned to a previously examined RT inter- val; P-7820 to RT interval=10 sec, P-9275 to 40 sec and P-6441 to 20 sec. Exposure to a particular RT interval value was not ran- domly determined. Subject P-6441 finished the initial series first and subsequently was returned to the first value studied (i.e., RT interval=20 sec). In an attempt to minimize differences in the number of time-outs presented to each subject, P-9275 was subse- quently exposed to RT interval =40 sec. Subject P-7820 was exposed to RT interval =10 sec in order to obtain data, albeit between sub- jects, at each of the three longer RT intervals. Responding was allowed to stabilize at these values according to the stability criterion outlined in Experiment I, and the sequential inter-time- out-intervals during each session were recorded. Subsequently, the delay contingency was suspended, and time-outs were occasion- ally presented at variable times independently of responding, with distributions "yoked'' to those of the previous phase by program- ming inter-time-out-intervals equivalent to those obtained during the 20th preceding session (when the delay contingency was in effect). That is, the distribution of sequential inter-time-out- 81 intervals from each of the last twenty sessions under the time-out delay contingency was programmed in the s^me ordinal position for a single session. Since time-out presentations occurred at varying times response-independently and were yoked to presentations under the delay contingency, this condition was termed a "yoked variable- time" (yoked-VT) schedule of time-out presentation. All other para- meters of this procedure were equivalent to those in Experiment I. The yoked-VT schedule remained in effect for 20 sessions, at which point the delay contingency was reinstituted at the RI" interval value prevailing prior to implementation of the yoked-VT schedule. Results Absolute response rates and numbers of time-outs presented under the initial reexposure to the RT interval and the subsequent yoked-VT schedule are presented for each subject in Table 2. For each subject, the rate of responding during reexposure to the RT interval was very similar to that obtained during exposure to that value in Experiment I. The correspondence between the number of time-outs delivered during the first and second exposures was also good, although differences may be noted (e.g., data for P-7820). Response rates maintained under the postponement procedure and the subsequent yoked-VT procedure are shown, as a percent of the mean response rate under the postponement procedure, in Fig. 6. (Absolute response rates and numbers of time-outs presented during each session shown in Fig. 6 have been included in the Appendix.) co r-i VD 1 en CO H 1 i — i r-H 1 a-. en 1 02 o o 1 C3 o 1 • CO r~~ O a CD * o o c o o o O c Cvl o o c_ CJ O O o o CD o !XI CO rvl ^ — t * ** — - CM lt> "=t CM CO CO CJ> en ud en en Cxi CO co CM LTS «sj- ■ lo cm • i CC CM cm en O XT >> c rO OJ r- J~ O) rd -a o. cj cu a o Figure 6. Daily session response rates for each subject under the delay and yoked-VT contingencies. Data were taken from the last 20 sessions under the delay contincency (to the left of the vertical line) for from the 20 sessions th* yoked-VT contingency was in effect (to the right). Response rates are expressed as a percentage of the mean rate during the last 20 sessions under the delay contingency. R-T=IOsec id VT TO 84 o» w \ ;v '-7 ? & \ P-7320 LiJ h- < LU 00 o Q_ 00 LiJ OC LJ R-T=20sec Yoked VT TO UJ 00 < m ^O ,50- R-T=40sec Yoked VT:TO o-> r SESSIONS 85 Removing the response-contingent delay decreased rates of respond- ing during time-in by at least 50% in every subject within the 20 sessions the yoked-VT schedule was in effect. Neither the degree of relative suppression nor the rate with which responding was sup- pressed appeared to be systematically related to the RT interval value under the postponement procedure. Absolute response rates under the yoked-VT procedure were, by contrast, inversely related to the RT interval (after 20 sessions exposure to this procedure). Intrasession patterns of responding maintained in each subject under the delay and the yoked-VT procedures are depicted in Fig. 7. Cumulative response records presented were taken from the last twenty sessions under the delay procedure or from the twenty days the yoked-VT schedule was in effect. Three pairs of records are shown for each subject, taken from the 1st, 11th and 20th session. The pairs of records are from sessions during which the delay con- tingency was in effect (labelled "R"), and from the sessions under the yoked-VT procedure (labelled "Y") which were matched with re- spect to time-out presentation to the former. (The records have been overlayed to highlight the correspondence between inter-time- out-intervals under the two procedures.) While response rates un- der the yoked-VT procedure generally progressively declined with extended exposure to this contingency, no systematic differences were observed in the patterns of responding. The subjects exposed to the two longer RT intervals prior to the yoked phase (i.e., P-6441 and P-9275) both paused for long periods during the middle >1 1 ,• — , Cl) err TJ 0) S~ c: -I-1 (•I cu ..V — > T) "XT 4- .<■.-. o o C7 QJ l_ o +-> >- •r- C) O 4- c ) O tn Cl 4-> Cl) S~ a; c C) XT. QJ a. s~ O +■> ■+-> C/l -l-J 1— 0) 4-> r 4- :> 00 C) ■4-> +J o £Z i ■r— C!J o tn X3 e T5 (■■) !~ <+- T J^ :>) Cl) T3 C) trt d: o r~ tj •r— x: - >. ^_> TJ +-> +-> o -a u cu UJ JC t- OJ -O jr. -o CJ n H- c; 4J TJ c 4- S- s ,a CU o X c c IT, T3 Cl) Cl) C!J Cl) • 1— r — ■ C <*- j_ • £ - — -* "J; 1 — 3 rtl (/I .c: m 4-> m >l L0 c; c •i — S o c CO o ro S_ >> CD ■!- 10 ifl a i) C7. in E u) i — CJCCWOnJffi O CJ -r- CD M- tj r: •r- Ul CTi-P 10 O O in -a c c -a o t- to s- t- o o cu — - c a> o +-> o c: > ro to o c: -i- o -c aj o >>tj E • o u o: o i« c aj m a) CD r— O S- E +J >, QJ CL u • rcs ~a to tr. ck +-> d)Cr- CD CD -r- ST. r— OCUCL)S-(DLi- 4- i- ISI +-> CiJ b ca <+- TJ O -C QJ c 3 4- tO O 1 o cr.'-c: c TJ v- (O CD to C- TJ -ii to o <- o to 4- O QJ CJ CO CO CJ >- to (O c ) S- (O QJ 4-> QJ +-> a; CD OJ S~ B i — C CXI CO C (O Z3 JC CL) to C/l -o +-> r- +J o. QJ c to ( > CL) s_ O rO S- 4-> .c O-i— 4- jr. 4-> QJ 4-) iyi TJ OJ jl; n a> cj (/) CJ > QJ +-> n s.- jr. TJ Q_ UJ S- i < p 1- CL cO (!) 0) o o - to i_. c/l 0) c *^ CI) (/I a> -o ai CJ aj cj +-> CO ■n -Q r— C) C) CJ m r- C ) QJ -Q s- TJ ^-J o > cO ro C r; CO ,— sz (C CM o _C - — - (J o (\J CO O s,a oos 88 of the 20th session under the yoked-VT procedure, and responded earlier and later in the session at rates reduced below those un- der the delay procedure. Such intrasession variation? in response rate were not observed with P-7820, who, although responding at rates lower than those under the delay contingency, still responded at substantial rates after 20 days under the yoked-VT procedure. Reinstatement of the postponement contingency increased re- sponse rates to values comparable to or above those observed prior to the yoked-VT procedure. The length of this transition varied between subjects, with P-7820, P-6441 and P-9275 responding at rates equal to or above the mean rate under the postponement pro- cedure after 10, 25 or 1 session, respectively. Discussion The results of Experiment II indicated that 1) response rates (and to a lesser degree time-out rates) obtained under reexposure to an RT interval value were highly comparable to those obtained under initial exposure to that value during Experiment I, and 2) the delay contingency was essential in maintaining the rates of responding observed under free-operant avoidance procedures when time-out is used as an avers ive stimulus. The decreases in response rate observed when distributions of response-independent time-outs were exactly matched to those of the immediately preceding response- contingent delay procedure argue against the notion that key pecking observed under the delay procedure was governed solely by stimulus- re in forcer contingencies. 89 Although the present results indicate that the delay contin- gency was crucial in determining the rates of responding engen- dered, they do not rule out the possibility that elicited key peck- ing directed at the time-in stimulus occurred and thus contributed to the overall rate of responding. Recall that the absolute rate of responding under the yoked-VT procedure was inversely related (after 20 sessions exposure) to the value of the preceding RT inter- val value. At least two interpretations of this effect are possible. First, it might be suggested that shorter delays occur between responses and subsequent response-independent time-outs as the aver- age inter-time-out-interval decreases. This may increase the like- lihood that "superstitious" negatively-reinforced responding will occur at higher rates when the yoked distribution is taken from a preceding condition involving a shorter RT interval (and hence, possibly shorter inter-time-out-intervals). Alternatively, it might be argued that decreasing the RT interval increases the num- ber of time-outs delivered (or the probability of short inter-time- out-intervals) and thus engenders more elicited pecking by decreas- ing the relative amount of "time-in" time (cf., Terrace, Gibbon, Farrell & Baldock, 1975). Both the "superstitious maintenance" and the "elicitation" notions rest on the assumption that the num- ber of time-outs delivered increases with decreases in the RT inter- val. Although an attempt was made to minimize differences between subjects in the number of time-outs delivered during the yoked-VT condition, some between-subject differences may be noted (see Table 2). These two interpretations cannot be evaluated independently under the procedures used thus far; either, both or neither could be correct. Assuming the elicitation notion to be true, it is possible that the slopes of the function relating response rate during time-in to RT interval obtained during Experiment I are greater than they would be in the absence of elicited behavior directed at the stimuli on the response key (given the added assumption that shorter RT intervals elicit more signal-directed pecking). It is entirely possible that key pecking is controlled by response-contingent delay of time-out, but not by the length of the consequent delay. Experiment III provided evidence sug- gesting, however, that this is not the case. CHAPTER VI EXPERIMENT III In food-deprived pigeons, pecking directed at some stimulus typically occurs only when that stimulus signals a higher fre- quency or probability of food presentation than that signalled in the absence of that stimulus (e.g., Brown & Jenkins, 1968; Gamzu & Williams, 1973; Keller, 1974). Additionally, the probability and/ or rate of elicited pecking is inversely related to both the rela- tive and absolute duration of the positively-correlated stimulus (e.g., Baldock, 1974; Spealman, 1978; Terrace, Gibbon, Farrell & Baldock, 1975). Hence, a continuously present stimulus (i.e., one of long duration which is non-differentially correlated with the presentation of food) should be less effective in eliciting pecking than shorter, differentially-correlated stimuli. Keller (1974) developed a procedure under which key pecks to one operandum (the "food" key) occasionally resulted in the pre- sentation of food while responses to a second key had no scheduled consequences. Presented on this latter key (the "signal" key) were stimuli correlated with the availability of reinforcement contingent on responses to the food key which was continuously il- luminated with a single stimulus. Keller argued that responses to the signal key were predominantly elicited key pecks, since 91 92 they only occurred when the two stimuli presented on it signalled non-equal frequencies of food presentation, and also since responses were directed primarily at the stimulus signalling a higher fre- quency of food presentation. He argued further that those occurring on the food key were predominantly operant key pecks maintained by response-contingent reinforcement, since response rates on the food key changed only as a function of the frequency of reinforcement. His procedure, then, allows for the "topographical tagging" (cf., Catania, 1971, 1973) of presumably different response classes; operant responses on the food key and elicited responses to the signal key. The use of such a procedure may clarify interactions between negatively-reinforced and elicited key pecking under free-operant avoidance procedures involving time-out from response-independent food presentation. To the extent that elicited key pecks to the time-in stimulus combine with those (operant) key pecks maintained by time-out delay, the separate contributions of each may be assess- ed by relocating the stimuli correlated with time-in or time-out away from the operandum associated with response-contingent delay of time-out. By projecting these correlated stimuli onto another response key, not only may operant responses be recorded in the relative absence of interactions with elicited responses, but also an independent measure of elicited responding may be automatically obtained. Experiment III examined the effects of response-contingent delay of time-out under such a "two-key" procedure. As in Experi- ment I, a range of RT intervals was examined while maintaining a contant TT interval. Differences between the results of the first and present experiment (at least possibly) may be taker as evidence for the contribution of elicited key pecking under the first "one- key" procedure. Method Subjects The subjects were the same as in the previous experments. Apparatus The same experimental appartus was used, with the exception that plexiglas extensions, similar to the one described earlier, eventually were added to both side keys, located 8 cm (center to center) to either side of and in the same horizontal plane as the center key.. Of these, the left key was illuminated and operative. A static force in excess of 0.15 N to this key was recorded as a response. (The plexiglas extension was added to the right key to accomodate another experiment. Procedure Each subject was exposed to a different number of "two-key" procedures, depending on when in real time they completed Experi- ment II. Subject P-9275 was the first pigeon exposed to a two- key procedure. Under this first procedure, responses to the center 94 ("delay") key during time-in produced a "click" and postponed the next time-out for the period of time specified by the RT interval as in Experiment II, but this key was now continuously illuminated amber. The left ("signal") key was marinated white or r^d , correlated ab before with time-in and time-out, respectively. Responses to this key, however, like responses to the delay key during time-out, produced no experimentally-arranged consequences. After 40 sessions under this procedure, the side keys, to this point recessed behind the front panel, were modified by the addi- tion of the plexiglas extensions described above. Following this modification, P-9275 and P-6441 were exposed to this procedure for 14 and 9 sessions, respectively, at which point the stimuli on the keys were altered. The delay key was now continuously illuminated white, while the signal key alternated from blue ("time-in") to green ("time-out"). (The variables responsible for these procedur- al variations are discussed below.) All subjects were then exposed to this "revised" procedure, and the RT interval was manipulated across the same range of values as in Experiment I while the TT interval remained constant at 5 sec. All other parameters of this procedure (e.g., time-out duration, frequency and duration of grain presentations, etc.) were the same as in the previous experiments. The number of days exposure and order of exposure to the different RT interval values are presented for each subject in Table 3. After extended exposure to these procedures, P-9275 responded only infrequently, and was not subsequently exposed to other RT interval values. TABLE 3 ST. OF CONDITIONS AND SUMMARY MEASURES FOR EACH SUBJECT DURING EXPERIMENT III CD S_ 5- O •r- O +-> -t-> ^ o •r- +-> rO -o S- c Oio o sz sz cj +J c_> to "O — - c: to ^— rs c t/j c CD i— 'r- i— re! -f-> =3 S- S~ Xj •i- CD t- U -t-> S- C +-> -o •■- in CD •■- KTl I — "O o c£ r— S- O CD CD -C S +J o 3 in>* err <- CD -(-> <-o I- 4- i <* 4- T- D_ 4- G.) -O CT > c c •r- -i- r3 u_ 4-> rd i/i - — i- , — 1— CO C"> cjq: c 4- KH O C) 4- +-> Ol • o rs O i — -O 1 (/) "1— •f-5 C 5- 0) O-P in t- -r- tO ITS rs 4-> -r- ct> -s "a (D •i- -O s~ U_-r- S- fT> S_ CD l/l 4J CO. 1/1 Q a> o sl- it 7:1 m o n h- i O ii H i in n ! CC o o O C\J CO I Q_ — r o 10 O dO/s,l«| O-O 03 Hd ~I3H # — 3 ooi x Ainiavao«d 1 1 0 exercised control over delay-key pecking. R-sponse rates on the delay key for both subjects were consistently fr.uc.li higher than rates on this key during time-out. Furthermore, the systematic changes in time-in response rate on the (continuously i 1 laminated) cielay key strongly suggest, that key pecking was controlled predominantly by the length of response-contingent time-out delay &p.-d not by any changes in stimulus-reinforcer relations resulting indirectly from manipulations of the RT interval value. The demonstration in the present experiment of systematic control over key pecking by response-contingent time-out delay independent of these other pos- sible sources of control adds credence to the notion that respon- ding of these subjects during the first experiment was similarly controlled. The behavior maintained under the present procedure was simi- lar in many respects to behavior maintained in other species using more conventional free-operant avoidance paradigms. This similar- ity arises not only with respect to the response rate vs_. delay- length function, but also with respect to the patterns of behavior engendered. This is not to suggest, however, that stimulus- reinforcer contingencies do not play a role in key pecking main- tained under free-operant time-out-postponement procedures. Evi- dence of sue!; control over responding, to varying degrees, stems from a number of the present results. First, there is the behavior of P-9275. This subject's beha- vior did not show any control over rate of delay-key responding by Ill the RT interval length. After initially revealing control by the signal-key stimuli (i.e., higher time-in than time-out delay-key response rate:.), this subject subsequently responded indiscrimi- nately on the delay-key while responding on the signal -key primar- ily during time-in. The gradual development of signal-key pecking i;iay reflect a ''catalytic" property with respect to such behavior inherent in the procedure. That is, given that delay-key pecking occurs at some minimal rate, time-out presentations will occasion- ally be delayed. For example, at the longest RT interval used in the present study, a single response during the TT interval would delay the next time-out presentation for a period slightly longer than twice the time-out duration. Thus, given a single response during each TT interval, the time-in stimulus would typically be illuminated for more than 75% of the session. Accordingly, the relative time-in time will be fairly high, presumably leading to a fairly low (possibly zero) rate of signal-key pecking (cf., Baldock, 1974; Terrace, Gibbon, Farrel & Baldock, 1975). If rates of delay-key pecking should for some reason diminish, however, the number of time-outs delivered would increase, decreasing the rela- tive amount of time-in time, and possible engendering or increasing the rate of signal -key pecking. To the extent that signal -key and delay-key pecking were incompatible responses, increases in the rate of signal -key necking would further decrease delay-key respon- ding, subsequently increasing time-out deliveries even more, which 112 in turn might lead to more elevated rates of signal -key pecking. Signal -key pecking also developed gradually in P-5441 and only when substantial numbers of time-outs were delivered, providing circum- stantial support for aa interpretation based on competitive inter- actions between delay-key and signal-key contingencies. The positive feedback loop described above may have contri- buted to the inability to maintain responding under the initial two-key procedure (i.e., delay key lit amber, signal key lit white or red). That is, given the extensive history of pecking a white key, it is likely that presentation of this stimulus on a new key (i.e., the signal key) would control a fair degree of responding. Responding on this key was, of course, ineffective in postponing time- out, and the number of time-outs delivered subsequently increased. This might have led to an increase in signal -key pecking, as outlined above, further hindering the development of delay-key pecking. The control over responding by the white stimulus was evidenced in the immediate transition in responding to the delay (white) key under the revised two-key pro- cedure (i.e., delay key lit white, signal key lit blue or green). .. That P-6441 did not peck the signal key under RT interval=5 sec in the presence of overall frequencies of time-out presentation comparable to those under RT interval=10 sec (during which signal- key pecking did occur) is somewhat perplexing. Pecking engendered by stimulus-reinforcer relations develops slowly in some subjects (cf., Brown & Jenkins, 1968), but usually is observed within a 113 single session. Since RT interval=10 sec was in effect for a rela- tively small number of sessions, it is possible, but not highly plausible, that such behavior would have developed with extended exposure to the RT interval value. Alternatively, it might be ar- gued that the high rate of delay-key pecking engendered under the shortest RT interval precluded the occurrence of signal -key pecking, in that delay-key and signal-key pecking are mutually exclusive responses which "compete'' for the time available to respond. Such a notion has, for example, been suggested to account for the decreases in the rate of behaviors "induced" by the intermittent presentation of positive reinforcement when the frequency of reinforcement in- creases beyond that which induces the highest rate of such behav- iors (e.g., Staddon, 1977, see particularly p. 133). The temporal distribution of signal -key pecking for P-6441 questions the validity of such a "competition" account. Recall that rates of signal -key pecking were highest shortly after a time-out and decreased there- after. Since the contingencies in effect directly after time-out (i.e., the TT interval) were constant throughout the experiment, it is not clear why signal -key pecking under the different RT inter- val values should be different., at least with respect to the high rates of pecking observed shortly after time-out. Such competitive effects would more likely be observed under conditions involving manipulation of the TJ interval length, not the RT interval. It is possible tfu;t behavior directed at, but not contacting, the signal -key occurred under all RT intervals at rates in accordance 1 1 n, with the relative time-out time. The occurrence of such unrecorded behavior could possibly have produced the decreases between Experi- ments I :anci III in the slope of the functions relating delay-key response rates during time-in and the RT interval by at least two means. First, since the stimuli associated with time-in or time- out were removed from the delay-key during Experiment III, respon- ding elicited by these stimuli during Experiment I (and thus contri- buting to the overall rate of responding observed) could no longer occur. Hence, any "additive" interactions between negative rein- forcement and stimulus-reinforcer contingencies during Experiment I were removed during Experiment III. In addition, the presentation of stimuli correlated with time-in or time-out away from the delay- key may have resulted in an antagonistic interaction between the two contingencies, to the extent that behavior directed at the delay- key and signal -key weremutually exclusive response classes. Both these effects would tend to decrease the slope of the response rate vs^. RT interval function, since more elicited behavior would be expected to occur at shorter RT interval values (values where the frequency of time-out presentation was relatively high). Although the slopes of these functions did decrease between Experiments I and III, the changes in absolute response rates responsible for the changes in slope are inconsistent with the notion just outlined. Specifically, both process-interactions described above would produce lower absolute response rates at Shorter RT intervals under the two-key than the one-key procedure, 115 either by the removal of any elicited key pecking and/or a competi- tive interaction between negative reinforcement and stimulus- reinforcer contingencies. Changes in absolute response rates for P-6441 are consistent with this prediction. However, those for P-7820 are not. Although the slope of the function under the two- key procedure for P-7820 was in fact slightly reduced, absolute response rates were never lower than rates under the one-key procedure, and were occasionally much higher. How accounts stress- ing stimulus-reinforcer relations would handle these increases is anything but clear. Despite the interpretive difficulties encountered with the behavior of these two subjects, the absence of any control over delay-key responding under the two-key procedure for P-9275 ques- tions the source of such control during Experiment I. It is pos- sible that for this subject the apparent control by delay length primarily reflected changes in stimulus-reinforcer and not response- reinforcer contingencies. Several aspects of this subject's beha- vior indicate that this may have been the case. Only this subject showed a strictly monotonically decreasing function between RT interval length and the number of time-outs delivered during Experiment I. Response rates during time-in for this subject were also consistently lower than those for the other subjects. To the extent that response rates during Experiment I reflected the addi- tive control over responding by response-contingent delay of time- out and by the occurrence of pecking directed towards stimuli 116 correlated with the delivery of food, the absence of control by the former might predict the occurrence of lower overall response rater.. A better analysis of this notion would be provided by comparing response rates at each RT interval value with rates obtained under yoked-VT conditions for each value. This subject did show the smallest absolute change in response rate during Experiment II when the response contingency governing delay of time-out was sus- pended. Whether such small differences would have been observed under other RT interval values is, however, unknown. Informal observation of response topography suggests additional differences between the behavior of P-9275 and the other subjects. While both P-7820 and P-6441 most typically directed forceful, open-beaked pecks at thekeys while standing directly in line with them, P-9275 more often "nibbled" around the side of the keys, only occasionally with a force sufficient to record a response. The degree to which the plexiglas extensions used in the present study contributed to the development of this topography cannot currently be determined. Although initially employed to increase the proba- bility of response acquisition, such a modification may have re- tarded the development of control by response-contingent time-out delay, since a large number of P-9275' s "pecks" went unrecorded, and thus unreinforced. Finally, P-9275 was the only subject to never show any tempo- ral control over responding during RT intervals. It is possible that the random distribution of conditional IRT probabilities, 117 rather than merely reflecting the absence of control by RT interval length, represents control exercised by the 'random schedule of rood presentation used during the present set of experiments, it would be interesting in this regard to compare temporal control (with respect to food presentation) under a comparable delay procedure but using a periodic schedule of food presentation. Although the particular variables controlling these differences between the behavior of different subjects cannot be delineated at the present time, it appears that responding controlled by delay of time-out may share an additional similarity with other negative rein- forcement procedures, that of controlling the behavior of some sub- jects but not others. Subject selection has become fairly common- place in studies of negative reinforcement (e.g., see Hineline, 1977; Neffinger & Gibbon, 1975). The present procedures may pro- vide a valuable analytic tool with regard to the variables respon- sible for inconsistent response acquisition. It has been sugges- ted, for example, that acquisition may depend on the compatability of behaviors elicited by aversive stimulation with the response on which negative reinforcement is made contingent (e.g., Bolles, 1970, 1973; Hineline, 1977). Since the present procedures allow for the independent experimental manipulation of variables responsible for both the elicited as well as operant responses, acquisition and maintenance of either may be examined in the presence or absence of the other. An illustration of this strategy was provided in the 118 present experiment by "topographically tagging" elicited and operant responses. Other possible approaches include manipulations shown to influence signal -directed responding, such as the presence of general illumination (VJasserman, 1973), local ized vs_. diffuse sti- mulus presentation (e.g., Schwartz, 1974), or the use of an omis- sion procedure, where elicited responses cancel reinforcement pre- sentation (e.g., Williams & Williams, 1974). Results from such manipulations may provide prescriptions for the development of pro- cedures under which responding is more precisely controlled by negative reinforcement contingencies. Such manipulations might also provide interesting data on the frequently reported, but somewhat less frequently analyzed, pheno- menon termed "warmup." These repeated wi thin-session transitions from "ineffective" to "effective" responding have only recently been subject to a descriptive analysis (e.g., Hineline, 1978a, 1978b_), rather than being treated as procedural nuisances and dis- carded from data analyses. Hineline (1978a) suggested that decre- ments in early session response rates reflect the competing influ- ence of behaviors elicited or otherwise evoked by aversive stimu- lus presentation which tend to habituate across the session. This may, for example, account for the infrequent reporting of warmup when lever pressing of monkeys is studied under negative reinforce- ment procedures, since a history of intermittent delivery of aver- sive stimuli, rather than producing competing responses, has been 119 reported to evoke lever pressing in these subjects (for a review, see Hutchinson, 1977). Aspects of the present results provide some support for such a "competition" notion. Warmup effects in the present study, al- though not formally analyzed, appeared to occur more frequently under the two-key procedure than under the one-key procedure of Experiment I. This might be predicted, since any non-operant beha- vior under the two-key procedure would be directed away from the delay-key and thus more possibly compete with the negatively rein- forced response. This competition would less likely be observed under the one-key procedure, since behavior under operant as well as other sources of control would be directed towards the single key. It is additionally interesting that the majority of signal - key pecks for P-6441 , under the one condition where such responses were numerous (i.e., RT interval 10 sec), occurred directly fol- lowing the onset of the session and diminished thereafter. This is exactly the pattern suggested by Hineline. Whether the diminu- ation of signal-key pecking during the session represents a process akin to habituation cannot be determined on the basis of the pre- sent results, however. It is equally plausible to argue competition in the opposite direction. That is, non-operant behaviors decrease in frequency due to an increase in the frequency of a competing operant response. Again, the present procedure may be especially helpful in providing data relevant to these interpretations. For 120 example, signal-key pecking under the two-key delay procedure could be compared with such responding under a two-key procedure with yoked response-independent time-out presentations. If the decr2- ment in signal -key pecking observed across the session is solely related to habituation, changes in the "time-course" of signal-key pecking under the two procedures should be minimal. Alternatively, competition from negatively reinforced key pecking might be ex- pected to decrease the frequency of late session signal -key pecking under the delay- but not the yoked- procedure. The within-session patterns of responding during Experiment II (see Fig. 7) do not provide evidence for or against either of these interpretations. Rates of responding for P-7820 were constant throughout the session. However stable rates of responding had not developed by the 20th session for this subject, so it is possible that within-session patterns may have been different under the delay- and yoked-procedures with extended exposure to the latter. The other two subjects showed slightly more stable rates of respon- ding during the last several sessions of the yoked phase, and also showed slight differences in within-session response rates. Both subjects evidenced long pauses during the middle of the session, with responding occurring both earlier and later in the session. In that the time-in and time-out stimuli were projected on the key during this experiment, and thus, stimulus-reinforcer and possible "superstitious" avoidance contingencies were therefore inseparable, 121 the source of control over this responding is uninterpreted.-. A number of hypotheses may be ventured to account for this within session pattern of responding. For example, it might be suggested that responding early in the session represents the occurence of non-operant behavior like that Hineline suggested occurs during the early portions of sessions involving shock-postponement contin- gencies. The diminished response rates observed as the session progresses might then reflect the "habituation" of these responses to time-out presentations. Responding later in the session might be primarily operant in nature, and may have been engendered in response to heightened "motivational" variables arising from the repeated presentation to response-independent time-out. Alter- natively, responding early in the session might reflect "sponta- neous recovery" (cf., Catania, 1968) of extinguished negatively- reinforced operant behavior, while responding later in the session might reflect "facilitation" of non-operant behavior through re- peated presentation of the aversive stimulus (cf., Hutchinson, 1977, particularly pp. 422 ff.). The two-key procedures outlined above allow these hypotheses to be tested, by separating control over operant and non-operant behaviors to a degree unobtainable under the one-k^y procedure of Experiment II. The validity of these hypotheses, as well as any others which might be posited to account for the wi thin-session patterns of responding, awaits ex- perimentation involving comparisons between behavior maintained under two-key delay and yoked-VT contingencies. CHAPTER VII GENERAL DISCUSSION The key pecking maintained under the free-operant avoidance of time-cut procedure in the present study was comparable in many regards to behavior maintained under comparable stimulus-post- ponement procedures, independent of the particular species, re- sponse or aversive stimulus employed (see Hineline (1977) for a review). Thus, the present results strongly suggest that be- havior was maintained under the present procedure in ways simi- lar to responding under comparable procedures, while recognizing the possible contribution of non-operant variables. These vari- ables must always be accounted for when studying behavior main- tained by response-contingent time-out delay to avoid the pos- sibility of attributing changes in behavior to independent vari- ables other than the ones actually functioning to control be- havior. The assessement of separate sources of control over re- sponding may prove to be an important benefit of time-out-post- ponement procedures. Just as the analysis of behavior maintained by positive reinforcement has benefited by analysis of concomi- tant non-operant responses engendered by these procedures, the analysis of negative reinforce -nt may do likewise. The 122 123 possibility of the experimental manipulation of the degree of warm-up observed, through direct manipulation of elicited or induced behaviors stands as an illustrative example. The dvc- sent procedure may prove to be invaluable in this regard, in that behaviors engendered by negative reinforcement and other contingencies may be more easily separated, measured, and in- dependently manipulated than procedures involving other species, responses and/or aversive stimuli. Although non-operant behav- ior engendered by the present procedure may or may not be the re- sult of behavioral mechanisms similar to those which engender elicited or induced behaviors under more conventional negative reinforcement paradigms, the functional effects of such behavior may be very similar. That is, responding engendered by the sig- nalled presentation of reinforcement and by unsignalled inter- mittent presentation of aversive stimuli may involve contrasting behavioral processes. However, the functional contribution of such responses to behavior maintained by negative reinforcement may be parallel, to the extent that both interfere to some de- gree with the emission of the negatively-reinforced operant. The utility of this assumption, of course, can only be expressed in terms of the increase in the precision of prediction and con- trol of behavior under negative reinforcement procedures such an interpretation provides. The possibilities discussed above, although suggestive, await experimental verification. Even should efforts prove responding elicited by signalled reinforcement presentation functionally dissimilar to responding 124 evoked by intermittent aversive stimulation, characteristics of the present procedure should make it especially useful in the analysis of negative reinforcement. It provides for the rapid acquisition of responding in pigeons, an inexpensive yet hearty and long- lived experimental subject. It provides for the con- tinued extension of the analysis of negative reinforcement not only to another species, increasing the "interspecies generality" (Sidman, 1950) of functional relations between behavior and en- vironmental events, but to a highly studied response of this spe- cies—key pecking. In that a vast literature exists on the con- trol of key pecking by a host of variables, differences between negatively-reinforced key pecking of pigeons and for example, lever pressing of rats, may be analyzed without questions arising as to possible constraints resulting from some peculiar topo- graphical characteristic of the response. Finally the present procedure involves no special subject preparation, and is avail- able to investigators currently studying positive reinforcement contingencies without requiring any additional experimental ap- paratus. This may well prove to be the most attractive aspect of the present procedure (at least with respect to controlling the behavior of researchers), in that it allows for the immediate analysis of negative reinforcement contingencies by persons cur- rently studying only positive ones. One last possible point of relevance for behavior maintained under contingencies involving time-out-postponement pertains to 12rj current conceptualizations regarding the variables considered necessary and sufficient for the acquisition, and to a lesser de- gree the maintenance, of behavior by negative reinforcement. An implicit assumption regarding negative reinforcement held by many investigators is that any response class may come under the control of negative reinforcement contingencies largely indepen- dent of any extra-experimental variables. Although it has been recognized that some responses more readily come under control of negative reinforcement than others, these differences have generally been attributed to differences in the history of rein- forcement for such responses prior to experimental study (e.g., Hineline, 1977) or to the use of non-optimal stimulus and response parameters when studying different responses (e.g., Sidman, 1960, in particular pp. 54 ff.). Recently, a number of investigators, primarily Bolles (e.g., Bolles, 1970, 1973), have taken excep- tion to this view, arguing that the nature of negative reinforce- ment contingencies "in the wild" is usually not conducive to the gradual acquisition of a response from some highly malleable rep- ertoire. Animals requiring multiple "trials'' to learn to escape from a predator not only do not, they also leave fewer progeny, suggesting that natural selection would not favor the continued survival of species requiring multiple encounters. Thus, re- ponses emitted in the face of impending aversive stimulation cannot be selected by a previous history of reinforcement, ex- cept in the trivial sense that prior occurrences of "successful" 12G responses alio// the organism to continue behaving. Rather, it is argued, responses observed are innate reactions, the so-called species-specifio-ddfense-reactions (SSDRs), or at best slight modifications thereof, which are elicited by aversive stimulation. Differences in the rate of acquisition of any individual experi- mentally-specified response do not depend on differences in the history of reinforcement for that response, but rather on the ini- tial probability of each as an SSDR when first tested. Responses are not "selected for" by negative reinforcement contingencies, but rather are "selected against" by the presentation of aversive stimuli ("punishment") following an ineffective SSDR. Thus, run- ning may more readily be acquired than bar pressing as a nega- tively-reinforced operant in that it has a higher initial proba- bility of occurrence than other SSDRs; that is, it is a preemi- nent SSDR. The occurrence of a bar press, presumably an ini- tially less probable SSDR, depends on the punishment of initially more probable, but ineffective SSDRs. Once these SSDRs have been sufficiently suppressed, bar pressing may be reliably observed. Experimental evidence offered to support this notion is generally in the form of failures to acquire, or differences in the rate of acquisition of two or more experimentally specified responses. Although such differences nay no doubt be observed, the controlling variables responsible for such differences are no further delineated by appeals to innate SSDRs. Rather, such appeals are more likely to halt prematurely the search for 127 important differences in environmental controlling variables, by engendering a raUo sonse if analytic completeness. For example, the S::';.\ Interpret.! •"".ion begins by a^su.riico that avervive stimuli are I i f e-tlrrej r.en I no , and thus not amenanle to response ccquisi- tion through "trial and error.1' Villi le wary ayersive stimuli !'in the wild'' are no doubt lethal, this need not imply thai: they all are. Poikilotherms need not always "run from the sun" to sur- vive, but responses which monentarily terminate or reduce ex- posure to the sun do occur. More relevant to the present ex- periment, animals may learn, in foraging for food, to avoid lo- cations void of nutritional resources (i.e., learn to avoid geo- graphically defined "time-outs," so to speak) without instantly sucumbing to the possible lethal effects of remaining in such lo- cations for extended periods of time. It is becoming increasingly clear that modifications of im- mediately accessible environmental antecedent and consequent events play an important role in determining the reliability and/or speed of response acquisition under the control of nega- tive reinforcement contingencies. Responses which are more read- ily learned may be more fuitfully thought of as "species- typical" (Hineline, 19771 than species-specific. This distinction is more than mere semantics, in that SSDRs imply a degree of con- straint in the genetic history of the species not implied by the "species-typical" label. The species-typical classifica- tion promotes the search for commonalities in the histories of 128 species and/or responses with respect to environmental events, and suggests that modifications of discriminative or consequent stimulus control may produce orderly changes in the probability of a responses which would not be predicted a priori by SSiJP. ac- counts. For example, in the example previously discussed com- paring acquisition of running and bar pressing as avoidance re- sponses, it is possible that environmental variables may play a more important role than that attributed to them by SSDR ac- counts. Rather than reflecting differences in inherent tenden- cies to respond to aversive stimuli in certain ways, running may be acquired more readily because running, in addition to terminating or postponing primary aversive stimulation, may also remove stimuli paired with aversive stimulation--the physical surroundings in which aversive stimulation occurred in the past. Bar pressing, while postponing primary aversive stimulation, does not usually remove situational stimuli. Baron, DeWaard & Lipson (1977) demonstrated that subjects would preferentially respond on one of two levers concurrently available when, in addition to postponing shock, responses on one lever produced a "safe place" (i.e., a retractable shelf on which the subjects were never shocked) for a fixed period of time. Whether addi- tion of this contingency would enhance acquisition of a b^r-press avoidance response remains at present an interesting question. That key pecking was readily and reliably acquired under the present procedure supports the species-typical notion. While 129 it is plausible that pecking at conspecifics may be thought of as an SSDR, the biological significance of pecking the aversive stimulus used in the present study, a stimulus differentially correlated with the absence of food, is not readily ch'scernable. Such stimuli would seem to invite withdrawal (e.g., Hearst & Jenkins, 197'-) and serach in areas away from the stimulus , not approach and contact, with it. This appeared to be the case in the present studies; subjects generally turned away from the front wall of the experimental unit during time-out. In any case, responding was engendered primarily in the absence of the aversive stimulus, not elicited by its presence (i.e., subjects rarely pecked the time-out stimulus). As such, it would be difficult to interpret key pecking under the pre- sent procedure as an SSDR. How such behavior subsequently came under control of time-out delay is, from an SSDR orientation, a fortiorti, anything but clear. The present results suggest that it may be more useful to argue that control of key pecking through one set of contingencies (i.e., stimulus-reinforcer re- lations) was transferred to a second set, namely nenntive rein- forcement through time-out-delay. APPENDIX DAILY SESSION DATA FOR EACH SUBJECT DURING EXPERIMENT II SUBJECT P-7820 RE.SPON.SE RATE TO's Time -in Time -out Delay Yoked-VT Delay Yoked-VT 28.33 23.32 0.08 0.36 32 29.24 24.96 0.29 0.42 33 26.66 28.51 1.26 1.82 43 26.41 25.37 0.23 1.70 33 23.05 28.49 0.57 0.77 46 25.96 29.15 1.23 1.00 40 24.28 33.78 0.28 2.23 36 27.00 28.07 0.08 0.33 25 26.22 28.82 0.23 1.26 32 25.39 23.94 0.85 0.32 30 26.03 30.87 1.48 0.31 27 26.94 29.12 0.46 0.90 32 26.68 26.98 0.15 0.80 31 28.96 20.98 0.17 0.32 27 27.60 18.57 0.45 1.69 31 28.06 22.64 0.44 1.12 33 28.01 20.01 1.11 0.14 35 27.13 17.70 1.14 0.33 35 24.47 14.16 1.01 0.07 36 24.35 14.15 0.56 0.30 39 130 131 SUBJECT P-644 ' I L3P0N3E R/ iTE (R/Min) TO1; lira- -In Jijve -out D_elay_ ; fok2d-VT Delay LPJif^YI 15.60 8.38 0.23 0 25 15 1 A ■■ ; 13.82 1 3,n i!oi 20 L3 .93 16.82 1. 07 0.84 19 -i p g ; 1 5 . 43 0.28 0.13 12 13^55 11.56 0.22 0.22 16 13.42 9.83 0.13 0.53 13 13.68 5.95 0.26 0.63 14 18.51 3.92 0.00 0.63 7 14.38 4.86 0.00 0.60 11 12.95 6.52 0.57 0.38 22 15.34 6.77 0.56 1.08 11 15.03 10.33 1.19 0.68 17 10.16 11.58 0.74 0.39 36 14.40 5.39 0.49 0.51 16 12.97 5.81 0.51 0.44 19 14.29 4.82 0.42 0.29 13 15.38 4.29 0.24 0.48 14 14.58 7.51 0.60 0.40 22 14.71 6.39 0.52 0.20 19 17.65 5.23 0.28 0.44 11 14.06 ''4.39 0.14 0.42 11 SUBJECT P-9275 RESPONSE RATE (R/Min) TO's Time -in Delay Yoked-VT 10.61 3.58 5.41 2.62 5.70 2.57 5.04 2.57 3.88 5.64 4.25 7.26 4.29 3.88 5.09 2.93 3.67 2.01 3.59 2.58 3.49 5.23 3.56 2.58 3.49 3.37 4.23 2.90 4.01 2.53 4.02 2.28 4.35 1.93 4 . 54 2.01 5.04 2.58 4.3/ 3.92 Tin le-out el ay Yoked-VT 0.00 0.14 24 0.00 0.00 20 0.17 0.00 27 0.00 0.09 26 0.16 0.03 2? 0.00 0.25 28 0.08 0.09 27 0.11 0.00 18 0.08 0.11 31 0.00 0.00 31 0.00 0.15 41 0.13 0.12 39 0.00 0.00 38 0.07 0.00 25 0.03 0.07 26 0.09 0.00 24 0.00 0.18 19 0.25 0.10 27 0.20 0.00 20 0.08 0.00 26 i.ltb Alvc-s de r'orares, A. B., % Todorov, J. C. Signalled free-operani: 2/oidaiice of shock by piqsons pecking a key. Jourrcil of c_r^c- Experimental Analysis of Behavior, 1 977, 27, 231-291. Anger, D. The role of temoral discriminations in the reinforce- ment of Sidinan avoidance behavior. Journal of the Experi- mental Analysis of Behavior, 1953, 6, 447-506. Azrin, N. H. A technique for delivering shock to pigeons. Jour- nal of the Experimental Analysis of De-havior, 1 959 , 2 , 161- T63. Azrin, N. H., & Holz, W. C. Punishment. In W. K. Honig (Ed.), Operant behavior: Areas of research and application. Engle- wood CI iff si N7"J.: Prentice-Hall, Inc. 1965. Pp. 380-447. fiadia, P., Coker, C, & Harsh, J. Choice of higher density sig- nalled shock over lower density unsignalled shock. Journal of the Experimental Analysis of Behavior, 1973, 20, 47-55. Badia, P., Culbertson, S., & Harsh, J. Choice of longer or stronger signalled shock over shorter or weaker unsignalled shock. Journal of the Experimental Analysis of Behavior, 1973, 19, 25-32. Badia, P., Harsh, J., Coker, C.C., & Abbott, B. Choice and the dependability of stimuli that predict shock and safety. Journal o_f_ the Experimental Analysis of Behavior, 1976, 25, 95-111. Baldock, M. D. Trial and intertrial interval durations in the acquisition of autoshaped key pecking. Taper presented at the meetings of the Eastern Psychological Association, Philadelphia, 1974. Baron, A., DeWaard, R. J., & Upson, J. Increased reinforce- ment when timeout from avoidance includes access to a safe place. Journal of the Experimental An- lysis of Behavior, 1977, 27, 479-492. Baron, A., & Galazio, H. Clock control of human performance on avoidance and fixed-interval schedules. Journal of the Experiment! Analysis of Behjry U r ■, 1976, 26, 165-180. 132 133 Baron, A , I Kaufman, A. Human, free-operant avoidance of "time- out" from monetary reinforcement. Journal of the Experi- mental Analysis of Behavior, 1366, % 557-565. Bu;m3 '•-.'. M. Tire allocation and negative reinforcement. Jour- nal of the Experimental Aria lysis of behavior, 1973, 20, 311-322'; ~ e. Leipzia and Berlin: Benodict, J. C. Response-shock delay as a reinforcer in avoid- ance behavior. ' Journal of the_ Experimental Analysis of Be- havior, 1975, 24, 323-332. Bersh, P. J., & Alloy, L. B. Avoidance based on shock intensity reduction with no change in shock probability. Journal of the Experimental Analysis of Behavior, 1978, 30_, 233-300. Bersh, P. J., & Alloy, L. B. Reduction of shock duration as nega- tive reinforcement in free-operant avoidance. Journal of the Experimental Analysis of Behavior, 1980, 83, 265-273. Blouoh, D. S. The reinforcement of least-frequent interresponse- times . Journal of the Experimental Analysis of Behavior, 1966, 9, 581-591. Boakes, R. A. Performance on learning to associate a stimulus with positive reinforcement. In H. Davis and H. M. B. Hur- witz (Eds.), Operant-Pavlovian interactions. Hillsdale, N. J.: Lawrence Erlebaum Associates, 1977. Pp. 67-101. Bolles, R. C. Species-specific defense reactions and avoidance learning. Psychological Review, 1970, 77_, 32-48. Bolles, R. C. The avoidance learning problem. In G. K. Bower, (Ed.), The psychology of learning and motivation (Vol. 6). New York: ' Academic Press, 1973. Pp. 97-145. Bolles, R. C, & Popp, R. J. Parameters affecting the acquisi- tion of Sidmar.' avoidance. Journal of the Experimental Analysis of Behavior, 1964, 7_, 315-321. Bolles, R. C, Stokes, L. W., & Younger, M. S. Does CS termina- tion reinforce avoidance behavior? Journal of Comparative cln^ Physiological Psychology, 1956, 62_, 201-207. Boren, J. J. Isolation of post-shock responding in a free operant avoidance procedure. Psychological Reports, 1951, 9, 265- 266. 134 Borer,. J. J., -- deVilliers. ?. A. Reinforcement and response rate interaction in multiple random-interval avoidance schedules, Journal of the Experimental Analysis of Behavior, 1972, 13, 499- 507, deVilliers, P. A. The law of effect and avoidance: A quanti- tative relationship between response rate and shock-fre- quencv reduction. Journal of the Experimental Analysis of Be.Wior, 1974> 21' 223-235. deVilliers, P. A. Choice in concurrent schedules and a quanti- tative formulation of the law of effect. In W. K. Honig and J. E. R. Staddon (Eds.), Handbook of operant behavior. Englewood Cliffs, M. J.: Prentice-Hall, Inc., 1977. Pp. 233-287. Dinsmoor, J. A. Punishment: I. The avoidance hypothesis. Psychological Review, 1954, 61, 34-46. Dinsmoor, J. A. Escape from shock as a conditioning technique. In M. R. Jones (Ed.), Miami symposium on the prediction of behavior: 1 967 ; Aversive stimulation. Coral Gables, F'la.: University of Miami Press, 1968. Dinsmoor, J. A. Escape, avoidance, punishment: Where do we stand? Journal of the Experimental Analysis of Behavior, 1977, 28, 83-95. Dinsmoor, J. A., & Sears, G. W. Control of avoidance by a re- sponse-produced stimulus. Learning and Motivation, 1973, 4, 284-293. " '" " Dinsmoor, J. A., & Winograd, E. Shock intensity in variable- i n t e r v a 1 escape schedules. J o urnal of the E xperi mental Analysis of Behavior, 1958, T, 145-148." Ellen , P., & Wilson, A. Two patterns of avoidance responding. Journal of the Experimental Analysis of Behavior,, 1964, 77T7-9S. " ~ Ferrari, E. A., 8 Todorov, J. C. Concurrent avoidance of shocks by 'pigeons necking a key. Journal of the Experimental Analysis of' Behavior, 1980, 34, 329-333. 136 Ferrari, E. A., Todorov, J. C, S Graeff , F. G. Nondiscriminated avoidance of shock by pigeons pecking a key. Journal of the Experimental Anal ys i s of Behavior, 1973, 1_9, 211-218. Ferster, C. B. The use of the free operant in the analysis of behavior. Psychological Bulletin, 1953, 50, 263-274. Ferster, C. B. Control of behavior in chimpanzees and pigeons by time-out from positive reinforcement. . Psychological. Monographs, 1953, 72, No. 3 (Whole No.. 4617. Ferster, C. B., & Skinner, 3. F. Schedules of reinforcement. New York: Appl eton-Century-Crof ts , "1 957 . Field, G. E., & Boren, J. J. An adjusting avoidance procedure with multiple auditory and visual warning stimuli. Jour- nal of the Experimental Analysis of Behavior, 1 963 , 6_, 537- 543. Flye, B. L., & Gibbon, J. Partial avoidance contingencies: ab- solute ommission and punishment probabilities. Journal of the Experimental Analysis of Behavior, 1979, 3J_, 351-371. Force, D., & LoLordo, V. M. Signalled and unsignalled free- operant avoidance in the pigeon. Journal of the Experi- mental Analysis of Behavior, 1970, 1_3, 283-290. Foree, D., & LoLordo, V. M. Transfer of control of the pigeon's key peck from food reinforcement to avoidance of shock. Journal of the_ Experimental Analysis of Behavior, 1 974 , 22, 251-259. Freud, S. The problem of anxiety. New York: Psychoanalytic Quarterly and Norton, T936T" Galbicka, G., & Branch, M. N. Selective punishment of inter- re^ponse times. Journal of the Experimental Analysis of Behavior, 1981, 35, 3TN322. Gamzu, F., & Williams, D. R. Classical conditioning of a com- plex skeletal act. Science, 1971, UJ, 923-925. Gamzu, E. R., & Williams, D. P. Associative factors underlying the pigeon's key pecking under autoshaping procedures. Journal of_ the Experimental Analysis of Behavior, 1973, 1_9, 225-232 Gardner, E. T., & Lewis, P. Negative reinforcement with shock- frequency increase. Journal of the Experimental Analysis of Behavior, 1976, 25," 3-14. 137 Gardner, E. T., & Lewis, P. Paramaters affecting the maintenance of neuatively reinforced key pecking. Journal of the Experi- mental Analysis of Behavior, 1977, 28, 117-131. Gibbon, J., Berryman, R., S Thompson, P.. L. Contingency spaces end measures in classical and instrumental conditioning. Journal of the Experimental Analysis of Behavior, 1974, 21_, 585-505. Guthrie, E. R. The psychology of learning. New York: Harper, 1935. Hake, D. F., & Campbell, R. L. Characteristics and response- displacement effects of shock-generated responding during negative reinforcement procedures: Pre-shock responding and post-shock agnressive responding. Joiirnal of the Ex- perimental Analysis of Behavior, 1972, 1_7, 302-323. Harsh, J., & Badia, P. Choice for signalled shock as a func- tion of shock intensity. Journal of the Experimental Analysis of Behavior, 1975, 23, 349-355. Hearst, E. Multiple schedules of time-correlated reinforcement. Journal of the Experimental Analysis of Behavior, 1 960 , _3 , 49-52. Hearst, E., & Jenkins, H. M. Sign-tracking: The stimulus- reinforcer relation and directed action. Psychonomic Society Monograph, 1974. Herrnstein, R. J. Method and theory in the study of avoidance. Psychologogical Review, 1969, 76, 49-69. Herrnstein, R. J.3 & Hineline, P. M. Negative reinforcement as shock-frequency reduction. Journal of the Experimental Analysis of r^hayjor, 1966, 9, 421-430. Hineline, P. N. Negative reinforcement without shock reduction. Journal of the' Experimental Analysis of Behavior, 1970, 1_4, 259-268. Hinel ins, P. N. Negative reinforcement and avoidance. In W. K. Honig and J~ E. R. Staddon (Eds.), Handbook of operant bejiavijor. Englewood Cliffs, N. J.: Prentice-Hall, Inc., 1977. Pp. 364-41 4. Hineline, P. N. Harmup in avoidance as a function of time since prior training. Journal of the Experimental Analysis of Behavior, 1978, 29, 87-103."(aT~ 133 Hineline, P. N. Warmup in free-operant avoidance as a function of the response-shock=shock-shock interval. Journal of the Experimental Analysis of Behavior, 1978, 30, 28! -291. (b) Hineline, P. f!., 5 Herrnstein, R. J. Timing in free-operant and discrete- trial avoidance. Jjournal_ r'F the Experimental ? no 1 - ysis Of Behavior, 1970, 13, 113-126.' Hineline, P. N., S Rachlin, H, rioter on fixed-ratio and fixed- interval escape responding in the pi aeon. Journal of the Experimental Analysis of Behavior, 1969, 1_2_~, 497-401 . (aj~ Hineline, P. N., & Rachlin, H. Escape and avoidance of shock by pigeons peckinq a key. Journal oT the Experimental Analysis of Behavior, 1969, 12, 5'3?-538.(b) Hoffman, H., & Flescher, M. Aversive control with the pigeon. Journal of the Experimental Analysis of Behavior, 1 959 , 2, 213-218. Hull, C. L. Principles of behavior: An introduction to be- havior theory. New York: Appleton-Century-Crofts, 1943. Hunter, W. S. Conditioning and extinction in the rat. British Journal of Psychology, 1935, 26_, 135-148. Hurwitz, H. M. B., & Millenson, J. R. Maintenance of avoidance behavior under temporally defined contingencies. Science, 1961, 133, 284-285. Hutchinson, R. R. By-products of aversive control. In W. K. Honig and J. E. R. Staddon (Eds.), Handbook of operant behavior. Enalewood Cliffs, N. J.: Prentice-Hall, Inc., 1977. Pp. 415-431. Hyman, A. Two temporal parameters of free operant discrimi- nated avoidance in the rhesus^ monkey. Journal of the Ex- perimental Analysis of Behavior, 1969, 1_2, 641-648. Jowaisas, D. B. The behavior of pigeons under free-operant sched- ules of shock avoidance and shock -frequency reduction. Ph.D. dissertation, University of Florida, 1977. Kadden, R. H. , Schoenfeld, W. N., & Snapper, A. G. Aversive schedules with independent probabilities of reinforcement for responding and not responding by Rhesus monkeys: II. Without sionai. Journal of Comparative and Physiological Psychology," 1974/87, 1189-1T97. Kamin, L. J., Brimer, C. J., & Black, A. H. Conditioned s- ■ pression as a monitor of fear of the CS in the course of avoidance tra ining. Journal of Comparative and Physi- oloqical Psychology, 1963, 56, 497-501. 139 Kelleher, R. T., & Morse, W. H. Escape behavior and punished behavior. Federation Proceedings, 1964, 23, 803-817. Keller, K. The role of elicited responding in behavioral con- tract. Journal of the Exnerijj'ental Analysis of Bshavlor, "1974, 2l7"i.r"9^257. Klein, M., •■ Rilling, M. Effects of response-shock interval and shoe '<- intensity on free-operant avoidance responding in the pigeon. Journal of the Experimental Analysis _o_f Behavior, 1972, 1_8, 295-303." Klein, M., & Rilling, M. Generalization of free-operant avoid- ance behavior in piaeons. Journal of the Experimental Analysis of Behavior, 1974, 21_, 75-88. Knutson, J. F., & Bailey, M. I. Free-operant escape-avoidance of noise by rats. Journal of the Experimental Analysis of Behavior, 1974, 22, 219-229. Krasnegor, N. A., Brady, J. V., & Findley, J. D. Second-order optional avoidance as a function of fixed-ratio require- ments . Journal of the Experimental Analysis of Behavior, 1971, 15, 181-187. Lambert, J. V., Bersh, P. J. , Hineline, P. N., & Smith, G. D. Avoidance conditioning with shock contingent upon the avoidance response. Journal of the Experimental Analysis of Behavior, 1973, 1_9, 361-367. Leaf, R. C. Acquisition of Sidman avoidance responding as a function of S-S interval. Journal of Comparative and Physiological Psychology, 1965711, 298-300. Leander, J. D. Shock intensity and duration interactions on free-operant avoidance behavior. Journal of the Experi- mental Analysis of Behavior, 1973, 19, 481-490. Lewis, P., Gardner, E. T., & Hutton, L. Integrated delays to shock as neoative reinforcement. Journal of the Experi- mentaj Analysis of Behavior, 1976, 26, 379-386. Lewis, P., Gardner, E. T., & Lopatto, D. Shock-duration re- duction as negative reinforcement. The Psi^Jl?-1^^! Recurd, 1980, 30, 219-228. Lewis, P., Lewin, L., Stoyak, !!., & Muehleisen, P. Negatively reinforced key pecking. Journal_ of the Experimental Anal- vsis of Behavior, 1974, 2?., 8T^90_. " 140 Lib by , M. E., ft Church, R. M. Timing of avoidance responses by rats. Journal of the_ Experimental Analysis of Pehav- ior, 1974, 22, 513-517. Logue, A. W., ?< deVilliers, P. A. Matching in concurrent vari- able-interval avoidance schedules. Journal op the Experi- mental Analysis of Behavior , 1 3 7 8 , 29 , 61-6 5 . MacPhail, E. M. Avoidance responding in pigeons. Journal of the Experimental Analysis of Behavior, I960, lj_, 629-632. McMillan, D. E. A comparison of the punishing effects of re- sponse-produced time-out. Journal of the Experimental Analysis of Behavior, 1967, 10, 439-449. Morse, W. H., & Kelleher, P.. T. Determinants of reinforcement and punishment. In W. K. Honig and J. E. P.. Staddon (Eds.) Handbook of operant behavior. Engl ewood CI i f f s , N . J . : Prentice-Hall, Inc., 1977. Pp. 174-200. Mowrer, 0. H., & Lamoreaux, R. R. Avoidance conditioning and signal duration--a study of secondary motivation and re- ward. Psychological Monographs, 1942, 54 (5, Whole No. 247). Neffinger, G. G., & Gibbon, J. Partial avoidance contingen- cies. Journal of the Experimental Analysis of Behavior, 1975, 23, 437-450. Pavlov, I. P. Conditioned Reflexes. London: Oxford Univer- sity Press, 1927. Powell, R. W., & Peck, S. Persistent shock-elicited responding engendered by a negative-reinforcement procedure. Journal of the Experimental Analysis of Behavior, 1959, 12, 1049- 1062. Rachlin, H. Autoshaping of keypecking in pigeons with negative reinforcement. Journal of the Experimental Analysis of Behavior, 1969, 1_2, 521-5317" Rachlin, H., & Herrnstein, R. J. Hedonism revisted: On the negative law of effect.. In B. A. Campbell and R. M. Church (Eds,). Punishment and avers ive behavior. Mew York: Ap- pleton-Century-Crofts, T969. Pp. 83-109. Rachlin, H., & Hineline, P. N. Training and maintenance of keypecking in the pi neon by negative reinforcement. Science, 1967, 157, 954-955. 141 Rescorla, R. A. Pavlovian conditioned fear in Sicilian avoidance learning. Journal of Comparative and Physiological Psych- ology, 1968, 65, 55-60.' Rescorla, R. A. Establishment of a positive reinfo.rcer through con era st with shock, Journal of Comparative and Physi- ological Psychology, 1969, 67, 260-263. Reynold, c. S. Behavioral contrast. Journal cf the Experi- mental Analysis of Behavior, 1961 , 4_, 57-71 . Rilling, M., & Budnick, J. E. Generalization of excitation and inhibition after different amounts of training of an avoidance baseline. Journal of the Experimental Analysis of Behavior, 1975, 23, 207-215." Schlosberq, H. Conditioned responses in the white rat. Jour- nal of Genetic Psychology, 1934, 45, 303-335. Schoenfeld, W. N. An experimental approach to anxiety, escape and avoidance behavior. In R. H. Hoch and J. Zubin (Eds.), Anxiety. New York: Grune and Stratton, 1950. Schoenfeld, W. N., & Cole, B. K. Stimulus schedules: the t- T systems. New York: Harper and Row, 1972. Schwartz, B. Autoshaping and behavioral contrast: the key to contrast is on the key. Paper presented at the meet- inas of the Eastern Psychological Association, Philadel- phia, 1974. Schwartz, B., & Coulter, G. A failure to transfer control of key pecking from food reinforcement to escape from and avoidance of shock. Bulletin of the Psychonomic Society, 1971,1, 307-309. Schwartz, B., & Gamzu, E. Pavlovian control of operant behav- ior: An analysis of autoshaping and its implications for operant conditioning. In V!. K. Honic and J. E. R. Stad- don (Eds.), Handbook o_f operant behavior. New York: Prentice-Hall, Inc., 1977. Pp. 53-97. Shimp, C. P. Synthetic variable-interval schedules of rein- forcement. Jour -.'.I of the Experimental Anal_ysis_ of Be- havior, 1973, 1J9, 311-330. Shiinp, C. P., & Uheatley, K. L. Matching to relative reinforce- ment frequency in multiple schedules with short component duration. Journal of the Experimental Analysis of Dehav- ior, 1971, 15, 205-210. 142 Shnidman, S. R. Extinction of Sidman avoidance; behavior. Jour- nal of the Experimental Analysis of Behavior, 1968, 11", 153-T56. Shu 11 , P. L., Spear, D. J., & Bryson . A, F. Delay or rate of food delivery as a determinant of response rate. Journal of the Experimental Analysis of Behavior, 1981 , 35", 129- Sidman, M. Two temporal parameters in the maintenance of avoid- ance behavior by the white rat. Journal of Comparative and Physiological Psychology, 1953, 4_o, 253-261 Sidman, M. Some properties of the warning stimulus in avoid- ance behavior. Journal of Comparative and Physiological Psychology, 1955, 48, 444-450. Sidman, M. Conditioned reinforcing and aversive stimuli in an avoidance situation. Proceedings of the Mew York Academy of Sciences, 1957, 534-544. Sidman, M. Tactics of scientific research. Mew York: Basic Books, 1960. Sidman, M. Classical avoidance without a warning stimulus. Journal of the Experimental Analysis of Behavior, 1962, 5, 245-257. Taj Sidman, M. An adjusting avoidance schedule. Journal of the Experimental Analysis of Behavior, 1962, 5_, 271 -277. IF]" Sidman, M. Avoidance behavior. In W. K. Honig (Ed.), Operant behavior: Areas of research and application. New York: Appleton-Century-Crofts, 1966. Pp. 448-498. Sidman, M. A., & Boren, J. J. The use of shock-contingent vari- ations in response-shock intervals for the maintenance of avoidance behavior. Journal of Comparative and Physi- ological Psychology, 1957, 50, 282-2877(7] Sidman, M. A., & Boron, J. J. The relative avers iveness of warning signal and shock in an avoidance situation. Jour- nal of' Abnormal and Social Psychology, 1957 r 55, 339-344. (b) Sidman, M. A. , 8 Boren, J. J. A comparison of two types of warning stimulus in an avoidance situation. Journal of Comparative and Physiological Psycholony, 1957, 50_, 282- 287. fc) Skinner, Is. F. "Suoerstition" in the pigeon, genmenta] Psychology, 1948, 38, 168-172. Skinner, B. F. Science and human behavior. Flew York: Mac- Mi "Nan, 19oT: Smith, G. D. Extinction of free-operar.t avoidance in rats. Ph.D. dissertation, Temple University, 1973. Smith. J. B., S Clark, F. C. Two temporal parameters of 'Tood postponement. Journjl of the Experimental Analysis of Behavior, 1972, 18, 1-12. Smith, R. F., f'.ustavson, C. R., & Greyor, G. L. Incompatibil- ity between the pigeons' unconditioned response to shock and the conditioned key-peck response. Journal of the Experimental Analysis of Behavior, 1972, 18, T47-153. Smith, R., & Keller, F. Free-operant avoidance in the pigeon using a treadle response. Journal of the Experimental Analysis of Behavior, 1970, W, 211-214. Snapper, A. G., & Inglis, G. SKED software system: Time- shared superSKED. Kalamazoo, Mich.: State Systems, 1978." Snapper, A. G., Stephens, K. R., & Lee, D. M. The SKED soft- ware system. Kalamazoo, Mich.: State Systems, 1974. Spealman, R. D. Interactions in multiple schedules: the role of the stimulus-reinforcer contingency. Journal of the Experimental Analysis of Behavior, 1976, 26, 79-93. Terrace, H. S., Gibbon, J., Farrell, L., & Ba'ldock, M. D. Tem- poral factors influencing the acquisition of an autoshaped key peck. Animal Learning and Behavior, 1975, 3, 53-62. Thomas, J. R. Time-out avoidance from a behavior-independent contingency. Psychonomic Science, 1965, 3_, 217-213. (a) Thomas, J. R. Discriminated time out avoidance in pigeons. Journal of the Experimental Analysis of Behavior, 1965, 8, 329-338. TbT Thorndike, F. L. Educational psychology: Briefer course. Mew York : Col umbi a Uni vers i ty , 1 91 4 . Todorov, J C. Component duration and relative response rates in multiple schedules. Journal of the Experimental Anal- ysis of Behavior, 1972, 17, 45-59. 144 rndorov, J. C, Ferrari, E. A. M., ft de Snuza, D. G. Ke.y peck- inn as a func" >n of response-shock and shock-shock in- terval'; in uns i ^nailed avoidance. Journal of the Experi- mental Ana lysis "of Behavior, 1974, 22, 215-218. iilrich, R. E., Holz, W. C, ft Azrin, N. H. Stimulus control of avoidance behavior. Journal of the Experimental AnaJ_- vsis of Behavior, "1954, T, 129-133. V'eWuve, T. Technique for differential reinforcement of rate of avoidance responding. Science, 1959, 129, 959-960. Wasserman, E. A. The effect of redundant contextual stimuli and autoshaoina the pigeon's ke.y peck. Animal Learning and Behavior, 1973, 1, 198-206. Weisman, R. C, ft Litner, J. S. Positive conditioned reinforce- ment of Sidman avoidance behavior in rats. Journal of Comparative and Physiological Psychology, 1969, 68, 597- 603. Weiss, B., ft Laties, V. G. Titration behavior on various frac- tional escape programs. Journal of the Experimental Anal- ysis of Behavior,' 1959, 2, 227-248. Weiss, B., ft Laties, V. G. Characteristics of aversive thresh- olds measured by a titration schedule. Journal of the Experimental Analysis of Behavior, 1963, 6_, 563-572. Williams, D. R., ft Williams, H. Automaintenance in the pigeon: Sustained pecking despite contingent non-reinforcement. Journal of the Experimental Analysis of Behavior, 1 969 , 12, 511-520. Zeigler, H. P., Levitt, P. W., & Levine, P. R. Eatino in the pigeon (Columba livia): Movement patterns, stereotypy, and stimulus control. Journal of Comparative and Physi- ological Psychology, 1980, 94, 783-794. Zener, K. The significance of behavior accompanying condi- tioned salivary secretion for theories of the conditioned response. American Journal of Psychology, 1937, 5fJ , 384- 403. BIOGRAPHIC,'!. SKETCH Gre< ■ ibicka was bom in El Paso, Texas, on September 6, 1955. Since then he has gotten much taller. His father, Joseph A. Galbicka, was a career Army man, and as such Greg spent the first eighteen years of his life vacationing around the world at the expense of the United States Government, which he would like to thank publicly at the present time. Following this, he "was the v ctirn of a series of accidents," deciding to become a psychologist in 1974. He attended the University of Florida, attaining a B.A. with High Honors in 1977, an M.S. in 1980, and finally a Ph.D in 1981, attempting to uncover the variables responsible for this unfortunate choice of career. He was less than successful. 145 I certify chat I have road this study :.nd t! it conforms to acceptable standards c> scho is fu'l'iy adequate, in scops and qu^tl ! ;y, us the degree of Doctor of Philosophy. : in ny op : n ion 'l.y presentation and dissertation for Marc N. Branch, Chairman Associate Professor of Psycho I certify that I have read this study and that in ny opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. g Edward F. Malagodi (/ Professor of Psychology I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. Henry S. Pennypacker Professor of Psychology I certify that [ have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, is scope arid quality, as a dissertation for the decree of Doctor of Philosophy. A4- / i / ,// Robert J. '-laldbillig / Assistant Professor of Psychology I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. John A. Cornell Professor of Statistics This dissertation was submitted to the Graduate Faculty of the Department of Psychology in the College of Liberal Arts and Sciences and to the Graduate Council, and was accepted as partial fulfillment of the requirements for the degree of Doctor of Philosophy, August, 1981 Dean for Graduate Studies and Research UNIVERSITY OF FLORIDA 3 1262 08553 5952