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BEHAVIOR MONOGRAPHS
Volume 3, Number 4, 1917 , Serial Number 15
Edited by JOHN B. WATSON
The Johns Hopkins University
The Effect of Length of Blind Alleys on
Maze Leaming:
An Experiment on Twenty-Four White
Rats
BY
JOSEPH PETERSON
Published
at Cambridge, Boston, Mass.
HENRY HOLT & COMPANY
_ 34 West 33d Street, New York
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The Journal of Animal Behavior
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especially interesting and valuable observations of behavior.
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Behavior Monog
For the publication of studies in behavior and intelligence which are
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BEHAVIOR MONOGRAPHS
Volume 3, Number 4, 1917 Serial Number 15
Edited by JOHN B. WATSON
_The Johns Hopkins University
The Effect of Length of Blind Alleys on
Maze Learning:
An Experiment on Twentv-Four White
Rats
JOSEPH PETERSON
Assistant Professor of Psychology, University of Minnesota
Published
at Cambridge, Boston, Mass.
HENRY HOLT & COMPANY
34 West 33d Street, New York
G. E. STECHERT & CO., London, Paris and Leipzig, Foreign Agents
THE EFFECT OF LENGTH OF BLIND ALLEYS ON
MAZE LEARNING: AN EXPERIMENT ON
TWENTY-FOUR WHITE RATS
THE GENERAL PROBLEM
“ How far are pleasurable results able to burn in and render
predominant the association which led to them? This is perhaps
the greatest problem of both human and animal psychology.”
So wrote Thorndike in 1898. The problem is not yet solved.
The problem arises from the fact, clearly pointed out by Thorn-
dike, that ‘‘ the connection thus stamped in is not contemporaneous
[with], but prior to the pleasure.”’: “‘ There is no pleasure along
with the association. The pleasure does not come until after the
association is done and gone.’ This problem, though raised
by Lloyd Morgan: in connection with experiments on learning
by the ‘trial and error ’’ method, has received very little but
theoretical attention from psychologists to the present time.‘
Its importance for the education process, including the informal
moral development by general social conditions, is certainly
such as not to be overlooked. The dearth of experimentation
1 Thorndike, E. L. Psychol. Mon., Ser. No. 8, p. 103. After nineteen years
of extensive work on certain phases of learning Professor J. B. Watson, who has
himself taken a considerable part in this experimental work, says practically the
same thing. In a review of Holt’s The Freudian Wish and Its Place in Ethics, in
which he considers a few artificial and inadequate illustrations of learning with
but slight attention by the author to the neural processes involved, Watson says:
“In these few experiences a genuine learning process is involved and the explana-
tion of this learning process—regardless of whether the act is acquired in, few or
many trials—is what I consider one of the chief problems in psychology.”” Jour.
of Phil. Psychol., etc., 1917, 16,, p. 89.
2 Tbid., p. 104.
3 Introduction to Comparative Psychology, 1894, Ch. 12. E.g., on page 213 Morgan
says: ‘‘ The successful response is repeated because of the satisfaction it gives;
the unsuccessful response fails to give satisfaction, and is not repeated.”
4 See, ¢.g., Smith, S. Limits of Educability in Paranecium. Jour. Comp. Neurol.
and Psychol., 1908, 18, 499-510. Meyer, Max, The Fundamental Laws of Human
Behavior, 1911. Thorndike, E. L. Animal Intelligence, 1911, Ch. 4. Haggerty,
M.E. The Laws of Learning. Psychol. Rev., 1913, 20, 411-422. Carr, Harvey A.
Principles of Selection in Animal Learning. Jbid., 1914, 21, 157-165. Watson,
J. B. Behavior, 1914, Ch. 7. Peterson, Jos. Completeness of Response as an
Explanation Principle in Learning. Psychol. Rev., 1916, 23, 153-162.
1
2 JOSEPH PETERSON
on the problem is likely due to the mind-body relations implied
in the early form of its statement.
It is desirable to rescue any problem as to how learning goes
on from mere theoretical discussions. Professor Watson has
already attempted this for the problem in question, though
not yet with marked success.’ Two groups of rats were allowed
to solve individually a certain problem; in the one group each
animal was fed immediately after the successful movements
that brought it into the food box, while in the other group each
rat was not allowed to take food for thirty seconds after entrance
to the food box. No difference in the learning of the two groups
was found. The experiment is regarded as only preliminary
to a further study of the matter. Two criticisms may be offered
on this experiment. In the first place, it is not on a wholly
objective basis. As reported the experiment did not seem to
be free from the assumption that the question at issue is whether
the pleasure of the eating had a “‘ stamping-in”’ effect, to use a
term of Thorndike’s, on the processes leading up to the eating.
‘““ Successful movements ’’ seem to be regarded as movements
bringing about this pleasure. If, in the second place, this is
not the true meaning of the author, it may be suggested that
the test of the effect of ‘‘ successful movements ”’ is not adequate,
since precisely the same kind of acts was necessary for both
groups of animals to get out of the situation presented by the
problem. Experience with rats will certainly suggest that after
an animal has once been fed in the food box it will for a time
work energetically and learn to run the maze without further
feeding of the kind, particularly if the odor is not carefully
excluded. As the habit becomes partly fixed it is questionable
whether the feeding, or even the smell of food, has very much
to do with the energy that the animal displays. So far as the
writer’s own experience goes—though he has made no definite
test of the matter—it appears that once the habit is well under
way the animal will display great energy in the usual way as
soon as placed into the entrance box; that the habit will unwind
itself on the basis of the numerous other stimuli which have
accompanied the process before. However, any criticism of
Watson's experiment on the basis of his report of the preliminary
6 An abstract of the experiment, which was reported in the Chicago convention
of ue American Psychological Association, is printed in Psychol. Bull., 1916, 13,
p. 77.
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 3
procedure is unfair, and our only purpose here is to point out
that there are real difficulties involved such as may give trouble
to even an experienced behaviorist. 4
The problem must be conceived in some other way, and in
terms of stimulus sand response as Watson has rightly insisted.s
Elsewhere the writer has attempted a statement of the general
problem in a form more acceptable for experimentation. The
general thought in mind, whatever the degree of success of its
statement may have been, was this: Response is never, in
the case of learning, at least, a reaction to a single stimulus.
The afferent impulse never begins at a given receptor as the
result of stimulus by a single object and thence passes into
motor channels from only one particular afferent fiber. The
situation in all learning is vastly more complex. A complication
of external stimuli is nearly always to be reckoned with; then
again, the afferent impulses from these stimuli are greatly
determined in their relative effects on response by impulses from
the proprio- and the entero-ceptive systems; and, in addition,
the responses resulting are to a large extent determined by
the general conformation of the organism. Different forms of
animals have different action systems, for example. The
pleasantness or unpleasantness of an act is only an inner indica-
tion as to’ whether the response, forced by the complex inner
organization (inherited and acquired) and the outer circum-
stances, or stimuli, is or is not in general harmony with the
conformation of the organism. The question of explanation
may resolve itself, then, wholly into one of the physical and
physiological circumstances. It was then,suggested that all such
factors as recency, frequency, and intensity of stimuli, which
may be conceived as involving only a single tract, are in them-
selves inadequate to account for learning. Indeed, they may
serve in all cases outside of mere chance associative connections
only as secondary aids to learning. In the usual cases certain
stimuli and their immediate effects continue for a time and
operate synchronously with others so that the response is a
resultant of these various circumstances. It may tentatively
tend this way and that, but will complete itself in the way that
is on the whole most consistent, when everything is taken into
° Behavior, p. 257. ; i F
7Peterson, Jos. Completeness of Response as an Explanation Principle in
Learning. Psychol. Rev., 1916, 23, pp. 153-162.
4 JOSEPH PETERSON
consideration. The most complete response possible, in this
sense,—the most consistent—has the advantage and will, other
things equal, survive over others. The various tentative begin-
nings of acts this way and that, moreover, are not to be regarded
as separate acts: they may easily, at a later juncture, be re-
solved into the ‘‘completest’’ act. Such conditions, it was
maintained, must be taken into consideration to account for
the selectiveness manifest in learning. This is a complex
“principle ’’ both to state and to test out in experiment; but
the organism and the behavior of an animal are inconceivably
complex, and over-simplification for the sake of clearness of
conception and of explanation is often a positive disadvantage
to progress in the biological sciences. Numerous evidences of
this statement might be given.
The experiment reported in the following pages was planned
in its main features when the article above referred to was
written, and it is there suggested in the concluding paragraph.
It was thought that varying the lengths of certain cul de sacs
in identical mazes might show a difference in behavior not
explicable on the basis of frequency, recency, and intensity of
stimulation. If, for instance, a tendency to enter a short cul
de sac is overcome with fewer errors in that particular case,
or in fewer runs through the maze, than are required when the
same cul de sac is lengthened somewhat, it would appear that
some other explanation than that based on the principles named
is necessary. On the basis of frequency and recency the animal
would stand the same chance, on emerging from the blind alley,
either of turning back-toward the entrance of the maze, on the
one hand, or of going toward the food box, on the other, that
it would with the blind alley longer. This would certainly be
true if acts are the individual and disparate affairs in trial and
error processes that they are usually assumed to be, each being
complete as a rule before the next is begun.
Watson says: “ This factor (frequency) alone is probably
sufficient to account for the maze habit. Apparently it is
difficult to obtain any explanation based upon other factors.’’s
® Op. cit., pp. 267, 268. In a footnote he says: “If it happens by chance that
any cul de sac is entered as frequently as any segment of the true pathway, it becomes
as firmly fixed as the true segment.’”” I cannot understand what the warrant is
for this statement. A careful tabulation of the detailed movements of some of my
rats in the maze shows that it is altogether contrary to the actual facts. In records
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 5
After pointing out, successfully to the writer’s mind, the difficulty
in the way of Thorndike’s principle of ‘“‘ satisfiers,” he contends
that there is no immediate connection backwards: between the
obtaining of food and the elimination of errors. Watson attempts
on the basis of the probability doctrine, suggested in another
relation by Stevenson Smith, to show how frequency alone may
suffice in the acquiring of maze habits. He argues that an
animal, having started along the maze path A, has an equal
chance on coming to a cul se sac X, all other factors equal, either
of taking B, the true path beyond the blind alley, or of going
into X; that on returning from X, in case of the wrong choice
having been made, it again has an equal chance of taking B.
It thus has a probability of 3/4 (or 1/2 + 1/2 of 1/2) of keeping
the right path.
If no other factor than frequency operates in such a case we
should expect an animal to continue entering the cul de sacs
indefinitely; for on turning back from any point toward the
starting place in the maze the same law must apply. The
chances are again 1/2 that any cul de sac passed will be entered,
and 3/4 that the animal will continue in its general direction,
now toward the starting point in the maze. In a maze with
several blind alleys, each of which has a chance of 1/4 of turning
any rat reaching it back toward the maze entrance, the proba-
bility would be very slim that the animal would at the first
trial reach the food. The returns would therefore tend to fix
the habit of entering cul de sacs as strongly as that of going
toward the food. Mere probability explains truly enough how
the animal gets to the food each time, but that 1s net the problem
of learning; it does not explain how it happens that on the whole
the second trial is better than the first, the third better than
the second, and so on. Frequency based on probability does
not bring such a result: it fails utterly to explain learning, even
in the simple case of the maze.» The real issue has been over-
picked at random, instances occur in numerous places of violations of the principle
stated. A detailed presentation of these instances will be reserved for a later
article, as proper attention to them here would lead us too far away from the main
purpose of the present paper. Instances are very frequent when the animal takes
certain blind alleys entirely contrary to the expectations based upon either fre-
quency or recency or of both combined.
9 This statement is based on actual data of a supposed case of a rat in a maze
of six cul de sacs whose “‘ choice’ at each bifurcation of the trail is determined by
the flipping of a coin. After considerable data by this method has accumulated—
after most any number of trials—it becomes very evident that if the frequency
6 JOSEPH PETERSON
looked as a rule. Watson does not try out his suggestion, or
follow it far enough to get to the real difficulty. It is not easy,
as Watson rightly admits,1° to see how the recency principle
can help out the situation. No one has given more on this
than the mere name. Both recency and frequency fail to explain
learning as a gradual change in the way of doing something,
involving the elimination of random acts. They do not show
what controls an act, but only that if it is controlled, or directed,
alike each successive trial it will become easier and more rapid in
performamcee.
On the other hand, if different ‘“‘ acts’ in a random trial and
error process are only more or less tentative expressions of the
one general act of getting food, for example, comparable to the
out-reachings of the pseudopodia of the ameba, and if in all
their changing forms these are related to the main performance
by numerous in-going and out-going impulses, it would seem
reasonable to suppose that errors of entering blind alleys would
be overcome, other things equal, in something like a direct
proportion to the length of the latter. This might be expected
to hold within certain limits of length, at least. It is not at
all implied in this view of learning, let it be clearly kept in mind,
that any conscious states, whether or not they are present, are
controlling or directing the animal. Indeed, it is just this view
that we regard as unfruitful, and for which we are seeking a
successful substitute. Instead of covering up the problem by
assuming that the animal ‘perceives relations,’ or makes
“practical judgments,’”’ or “‘ has ideas,’’ we are attempting to
meet it squasely and to state schematically how the complexity
of stimuli in the situation favoring learning can function so
that the animal may “learn by results.’ There can be little
question in fact that somehow the animal does learn by results.
Our problem is to understand how and by what kind of results.
Its solution would seem to have valuable bearings in the way
of substituting for current erroneous “ social forces’’ factors
(including ‘‘ pleasure and pain’’) used in explaining human
conduct, in the absence of better conceptions.
(or the recency, or both) of running through any unit of the maze be the determ-
ining factor in subsequent choices the rat never would learn the maze. As the
previous note states a similar tabulation of actual choices by an animal likewise
shows the inadequacy of the principles in question.
19 Op. cil., p. 269. The writer is working, however, with encouraging prospects
upon a method of testing the influence of recency, and he is finding that influence
much less potent than he had supposed.
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 7
THE EXPERIMENT
The experiment was carried out in the University of Chicago
during the months of July and August, 1916.1: Twenty-four
white rats, ranging in ages from about five to six weeks at the
time of the beginning of the experiment, were used. Of these,
nine were males and fifteen females. These were at first divided
into two main groups, the one consisting of. the fifteen females
and one small male and the other of eight males. The first
group began as untrained animals in the B-mazes, to be described,
and the second in the A-mazes. They were ear-marked and
grouped about eleven days before the experiment began, during
which time they were habituated to handling, and were fed
‘daily in the food box of the maze (in the separate groups) except
a couple of days while the maze was out of the laboratory for
remodeling. The food was bread soaked in milk, a definite
quantity being given each day to insure uniformity of bodily
conditions and of hunger. During the entire period of prepara-
tion and experimentation not a single rat showed any signs of
illness. The two main groups were again divided into control
groups, as will be explained later in ‘‘ The General Schedule
of Experiments.’’ These sub-groups were caged separately for
convenience of experimentation, but they were fed together
daily in the food box of the maze throughout the time of the
experiment and were also interchanged daily in the cages, 1. e.,
each sub-group was on any given day put into the cage occupied
by its control group during the previous twenty-four hours.
The purpose of these interchanges was to prevent the develop-
ment of group odors.
Only one maze in the laboratory was available. This was,
uJ desire to express my thanks here to Professors Angell and Carr for the privi-
leges of the laboratory and for the animals used in the experiment. With the
exception of aid from my brother, John C. Peterson, a graduate student in the
University of Chicago, I am wholly responsible for the experiment, both as to prob-
lem and method. My brother helped me plan the modifications of the maze avail-
able, and to get started with the experiment, which help I gratefully acknowledge.
We had planned to carry on the experiment together, but it was found after the
second day of experimentation that one person could record all the movements
satisfactorily and could secure greater uniformity in the conditions of the experi-
ment than was possible to two. : :
2 Through an oversight at the time of the segregation and ear-marking of the
animals the small male, No. 10, was classed as a female.’ The error was noticed
on the fourteenth day of the experiment, and after this time the rat was caged with
the males, 5, 8, 1, and 7, but it continued to run the IB maze with the females.
No difference from this change was noted in the behavior of the male or of any
of the other animals. No. 10 did not continue with the females in any other maze,
as will be seen in the schedule.
8 JOSEPH PETERSON
however, converted into two mazes as shown in figure I, by
means of a rearrangement of the partitions. Both mazes have
the same food box, and therefore only one of them can be used
at any one time in experimentation. IB (figure I) is a maze
with ten blind alleys, numbered from one to ten. The broken
line from the entrance, E, indicates the correct path to the
food. IA is another maze having but six cul de sacs, the entrance
being at E’. This maze is shown in the figure in heavier outlines.
Whenever the one maze was in use the entrance to the food
box from the other was, of course, closed. The mazes were
made of soft wood, and were stained black just before being
used in the present experiment. The alleys were uniformly
four by four inches in cross dimensions, and the partitions were
approximately one-half inch thick, By means of a number of
easily removable shutters, braced with triangular supports from
behind, the cul de sacs could be shortened as desired for the
purposes of the experiment. By this means each maze could
be converted quickly into a maze of a slightly different type,
having the same blind alleys but of relatively different lengths.
These shutters were also of soft wood stained black and had
the same cross dimensions as the alleys of the maze, so as to
fit tightly. In the figure these shutters are indicated by dotted
cross-lines in the blind alleys. Thus in Maze IB the blind
alleys 2, 4, 6, and 9 are shortened so that the ten blind alleys
together have a total length (about eleven feet) approximately
equaling the ten in Maze IIB, of which 1, 3, 5, 7, 8 and 10 have
been shortened as indicated.
Maze IA differs from Maze IIA on another principle: all the
cul de sacs in the first are of full length, as indicated, while the
second has them all shortened. In IA the total length of the
blind alleys is about eight feet, while in ITA it is about four feet.
The mazes were supplied with glass covers, with wooden
drop-shutters at the entrances and tin side-sliding shutters at
the food box entrances. In the experiments each animal was
first put into the food box and allowed to taste the food before
the first run, or trial. This was not only to strengthen the
incentive but also to insure uniformity in incentive and in
handling of the animal in all trials. In presenting the animal
to the entrance of the maze the experimenter was always seated,
with the entrance slightly at his right.
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 9
The groupings of the animals made in the experimental pro-
cedure are clearly and concisely shown in the general schedule
following, arranged according to the mazes used. Thus in Maze
IB the first rats used are those called Group Mu, the u indicating
that the animals were untrained. The rats of Group St were
trained, as indicated by the ¢; 2. e., they had learned another
maze. Frequent reference to figure I, in connection with the
study of this schedule, will make clear which maze was in use
for any group in question, and the exact modification of the
blind alleys.
FIGURE I.—The fourfmazes used, IB, IIB, IA, and ITA. The heavy lines mark
the division between the B- and the A-mazes. Dotted lines across blind
alleys show position of the shutters. E and E’ are the entrances to the mazes.
GENERAL SCHEDULE OF EXPERIMENTS
Rats used Practice distributions
Maze IB
Mu Group....... 7 females (9, 11, 12, 13, 14, 16, 18) and 1 male (10).
Two tests, or runs, daily for ten days, then four daily for
three days, then three daily for each rat until eight runs out of
ten were correct. (Rat 12 did not complete the habit in time
available.)
St Group........ 4 males (2, 3, 4, 6), trained on Maze ITA.
Three runs daily for three days, then an intermission for six-
teen days (see explanation on next page), then by the intensive
method the rats were run Aug. 29th and 30th each three times
at the following periods of day: 9-9:20, 9:40-9:55, 3-3:15, 3:30-
10 JOSEPH PETERSON
3:40, and 8:30-8:40,—total runs, twenty-four for each rat. All
records were left incomplete, but all rats were equally practiced
to the point of discontinuance. All animals were eager and
active.
Maze IIB
Nu Group....... 8 females (15, 17, 19, 20, 21, 22, 23, 24). . :
Rat 20 was blind in left eye. Distribution of practices pre-
cisely same as for Group Mu, in Maze IB, same days.
Ri Group........ 4 males (1, 5, 7, 8) trained in IA.
Distributions of practice same as for Sf, Maze IB, same days,
Practice periods, Aug. 29th and 30th: 9:25-9:35, 9:55-10:10.
3:15-3:30, 3:40-3:55, and 8:45-9. All records left incomplete;
rats eager and active.
Maze IA
Ru Group....... 4 males (1, 5, 7, 8).
Practice distributions same as for Mu, Maze IB.
Nt, Group....... 4 females (15, 20, 21, 22), trained on Maze IIB.
Three runs daily for each rat until habit was completed, eight
runs of ten correct.
Mt, Group....... 3 females (9, 13, 14), trained on Maze IB.
By intensive method: the three animals were given three runs
each, alternating with short periods of rest, during the forenoon
of Aug. 28th. Rat 14 completed habit in twenty-eight runs,
or trials; rat 9, in twenty-four runs; rat 13, in forty-one runs,
eleven of which were made early the morning of the following
day. All rats were eager and active, except 13 on the last run
of first day, when it took sixteen seconds following two runs of
two seconds each.
Maze IIA
Su Group. ...... 4 males (4, 6, 3, 2).
Practice distributions same as for the Rw Group in Maze JA.
Nf, Group.......4 females (17, 19, 23, 24), trained on Maze IIB.
Practice distributions same as for Né, in Maze IA.
Mf, Group....... 3 females (11, 16, 18), trained on Maze IB.
Practice distributions same as for Mu, and alternating after
each three trials with them. Each rat completed the habit,
getting eight out of ten runs correct, in a total of twelve runs.
All were very active and eager throughout.
This schedule is given as actually carried out, not exactly
as originally planned. It will be noted that the programs for
the two B-mazes are precisely alike, and that the same is true
of the A-mazes. This affords means of control of a number
of factors which otherwise might favor one or the other of the
control groups. Temperature conditions changed considerably;
it was also necessary to modify occasionally, to suit the time
at the disposal of the experimenter, the number of runs per
day by each animal. At the early stages of the learning there
was not enough time to give each animal more than two runs
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 11
daily. Later four runs daily were tried, but the eagerness of
the animals seemed’ in one or two cases to diminish in the last
‘run. Three runs a day proved to be very satisfactory. It was
originally supposed that each rat could learn both one of the
B- and one of the A-mazes during the time available for the
experiment—July 18th to August 30th—but a difficulty arose,
which had been underestimated in the planning. When the
male rats had finished their more simple problems—the A-
mazves—and were started on the B-maze problems, signs of
trailing the females appeared. To prevent this possibility the
male and the female groups of animals had been made to occupy
the same cages alternately in successive days. It was imprac-
ticable to wash the maze thoroughly before each experiment
for each group. The first day that the St and the Rt male
rats were run in the B-mazes, after the runs of the females,
there was no difficulty. On the second and the third day,
however, there seemed to be evidences of trailing and of excite-
ment, and some of the rats deposited urine drops in the maze
from the second to the fifth blind alleys. This seemed to
influence, as a guide, later members of the same groups (i. ¢.,
also males), and to stimulate them to make similar deposits
along the trail. Thorough washing of the entire maze with
soap water and Creolin-Pearson, a disinfectant, did not change
the behavior materially. Consequently, after the third day the
practices of these males were discontinued for sixteen days,
until the females had completed their problem. This experience
with the males seemed in only one (questionable) case to
influence in the least the runs of the females whose habits had
been already reduced to the stage of proprioceptive control.
The mazes, moreover, had. been carefully washed after the
second and the third day of the experience with the males
already described.
The postponement of the experiment with the males in the
B-mazes made it necessary to run them by the intensive method
described in the schedule, if at all. It was found that if each
rat was given three runs and then put back into the cage without
feed it could again be run soon after with no loss of eagerness.
In fact, the method worked surprisingly well. The fact that
the records had nevertheless to be left incomplete on this maze
so far as these rats were concerned does not affect the data so
12 JOSEPH PETERSON
far as they go, as the two comparable groups had identical
experiences.
Since the A-mazes were cleared earlier than the B-mazes, it
was possible to put into them, as indicated in the schedule,
some of the females—four on each A-maze—which first com-
pleted their original problem.* Finally,—leaving out the female
12, which did not complete its original problem until the maze
was taken over for the males, and the small male 10, which
had been running with the female group Mu—three females
were practiced on each of the A-mazes by the intensive method.
The results of these two groups are, for obvious reasons, strictly
comparable only to the twelfth trial inclusive, when the rats
in the IIA maze had completed their problem.
All comparable, or control groups were then run on the same
days, the same number of times, and as nearly as possible the
same time of day. Moreover, to give no possible advantage
of trailing to either group—and aside from the cases noted,
not between control groups, no such behavior was observed—the
group which was practiced first one day was second the next.
Both time and error results were noted. The experimenter
devised a system of short signs with which to record the com-
plete gross behavior of each animal. Returns in the maze were
noted as accurately as possible; only minor ones not reaching
cul de sacs or corners of the various maze alleys before being
corrected were left out of the records. Entrances into the blind
alleys were all classified by means of appropriate signs, into
three classes,—complete entrances, entrances about half way in,
and beginning entrances bringing the animal’s head and fore
part into the blind alley while the hind feet remained in the
true path. In the table of results these entrances constituting
the last class are in the column headed “ Start.” It was also
noted, as the animal emerged from the cul de sac, whether it
continued forward toward the food or turned back toward the
place of beginning. Hesitancies were also noted. Of these a
peculiar and amusing kind was frequent. Occasionally, an
1% To be sure that the two groups were of approximately equal ability the ani-
mals composing them were selected as follows: The first, third, fifth, and seventh
rats that completed Maze IIB were selected for Maze IA, with the long cul de sacs:
and the second, fourth, sixth, and eighth were taken for Maze IIA. In case of
any slight difference in the groups this would put the better animals into the more
difficult maze, so that the better results expected for IIA could not be due to
superior animals. :
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 13
animal would stop quickly at the entrance to a blind alley while
the head would vibrate very rapidly between the direction of
the true path and that of the tempting by-way. The record
here and there shows, for instance, that an animal would stop
at cul de sac 1, after having nearly inhibited the tendency to
enter this blind alley, and make, say, three double vibrations
(3 v. d.) with the head. This behavior is very suggestive and
will be considered later. On the whole it was found that the
full description of the animal’s behavior was much more valuable
for the present problem than the mere recording of time and
errors. Time records were, however, also kept.
14 JOSEPH PETERSON
TABLE I
GENERAL SUMMARY OF RESULTS IN THE B-MAZES
Blind alley....... | First | Second
Degree...........| Compl. | Half | Start. | Compl. | Half Start.
Direction......... E R FE R FE R FIE R F| E R FE R F
Runs Group
1 2 Mu IB }19 10 92 0 212 4 883 19 149 3 66 3 8
Si IB|6 3 3 1 14 4 10; 1 1
Nu IIB |18 9 9 3 3}5 3 228 19 910 4 61 1
Ri IIB | 4 4) 1 TG 17 3 41 1} 1 1
|
1- 5 Mu IB (37 15 22) 4 415 5 1044 23 21/17 6 11/11 4 7
St IB |12 4 8 2 1 #4216 #4 #1271 ~ «21 4 1 8
Nu IIB /27 15 1210 2 8 7 3 £4141 27 14/18 4 14] 2 2
Ri IIB|8 3 56 666 1 59 4 4) 3 311 1
6- 15 Mu 70 16 54455 2 3/2 2778 #5 3/5 5]13 13
Si 30,0 4 S26) 4 4| 7 7;/5 1 4/2 2| 8 8
Nu 25 5 2026 2 24/21 2116 2 410 2 95 1 4
Ri 4 446 1 5380 3 2715 3 2/3 1 216 6
16- 25 Mu 56 2 54/18 2 1614 45 2 3:5 1 46 6
Si 12 12)15 15| 7 7/1 Ted a BS 5
Nu 9 1. 8/10 10/22 1 21;8 1 7 3 311 1 10
Rt 3 2 13 1 27 «1 «67 6 110 3 73 3
26- 35 Mu 38 4 34/21 21| 7 7| 3 3] 7 7 4 4
Nu 4 4) 4 4/10 10) 5 510 1 910 1 9
36- 45 Mu 40 1 3917 1 167 7\ 2 1 1; 3 3) 4 4
Nu 1 1| 2 2| 8 8} t 1 7 7|16 16
46-55 Mu 30 30/24 21) 9 95 1 4/2 21 3 3
: Nu 1 1) 4 4| 6 6, 2 2) 5 5| 7 7
56- 65 Mu 19 19/19 19/12 12) 3 3] 2 2| 5 5
Nu 1 1,1 1 1 114 4
66- 75 Mu 21 2m}9 1 385 5| 2 2| 2 34 1 8
Nu 1 lj 1 1} 1 1
76- 85 Mu 9 9\ 9 97 7| 2 2) 2 2| 4 4
Nu | 1 al
86- 95 Mu 4 444 1 3 7 fi
Nu
96-105 Mu 3 3) 4 4 2 2
Nu
106-115 Mu 1 1| 3 3) 2 2) 1 1] 2 2
Nu
116-125 Mu 1 U2
Nu .
Totals IB....... 382 46 336/153 7 146) 86 6 80|107 37 70156 9 47/71 6 65
Totals IIB....... 82 26 561 72 6 66/120 9 111] 85 41 44/71 10 61165 3 62
Total number of entrances into cul de sacs, IB, 621 234.
Total number of entrances into cul de sacs, IIB, 275 221
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 15
TABLE I—Continued
GENERAL SUMMARY OF RESULTS IN THE B-MazeEs
Blind alley....... Third Fourth
Degree........... Compl. | Half Start. Comp). Half Start.
Direction......... E R FIE R FE R FE R FIE R FE R F
Runs Group
1- 2 Mu IB }10 4 65 O 510 3 7/23 8 bbl 4 3 #=1/2 vA
St IB|6 2 4 5 5.5 8 Be 2B & 2 5
Nu IIB }10 2 8/3 2 1/4 2 20 3 73 3) 1 1
Rt IIB 3 1 24 2 24 4
1- 5 Mu IB /|16 5 11) 6 612 3 930 10 20:6 4 24 1 8
St IB|7 2 5 6 668 3 52 2 Gt
Nu IIB 13 3 10/6 3 3/9 2 715 5 10) 5 5| 2 2
Ri IIB 4 1 34 2 26 1 5
6- 15 Mu 2 2 2 271 #1 A
St 2 1 Va 1 2 2
Nu 1 1 3 3}2 1 1
Rt 2 1 2 1 15 3 2 2 2
16- 25 Mu 2 1 #11 1 Law 2 2) 1 1
St af 1
Nu 1 1 2 1 15 5| 2 2
Ri Be 1a 1.2 2 2
26- 35 Mu 1 yj1 1 3 2 Qi yi ol 2 2
Nu 1 11 1 3 1 2
36- 45 Mu 1 1
Nu 2 2 1 1 2 2
46- 55 Mu 5 3 2 So I 22 4 4
Nu de | 1 1 1 1
56- 65 Mu 1 1 3 3 1 1
Nu 1 1 1 1
66- 75 Mu 1 1 1 1
Nu 1 yi 1
76 -85 Mu 1 1 2 TOF 2 2
Nu
86- 95 Mu 2 2 2 J, J
Nu
96-105 Mz - 1 1
Nu
106-115 Maz
Nu
116-125 Mu
Nu
Totals IB....... 40 14 2610 2 823 5 18/54 20 34115 9 618 3 15
Totals IIB.....: /.|17 4 138}6 3 3/21 5 16/33 13 20/20 2 18/16 2 14
Total number of entrances into cul de sacs, IB, 73 86
Total number of entrances into cul de sacs, IIB, 44 69
2
16 JOSEPH PETERSON
TABLE I—Continued
GENERAL SUMMARY OF RESULTS IN THE B-MAZES
Blind alley....... Fifth Sixth
Degree........... Compl. Half Start. Compl. Half Start.
Direction......... E R FE R FE R FRE R FE R FE R F
Runs Group ;
1- 2 Mz IB {30 18 12) 1 119 4 57 3 4 1 1]
St IB |j12 5 7 5 3 21 1 1 1
Nw IIB j21 8 13) 1 1}4 2 2:5 5}4 2 2:4 1 3
Ri WIB/}8 6 2 4 1 3/1 1
1- 5 Mu IB /46 27 19 1 113 «5 = #«68)10 5 51 12 1 I
Si IB |19 6 13 5 3 22 2) 1 lj 1 1
Nu IIB [31 10 21/1 16 3 39 2 75 2 37 2 «5
Ri WB/8 6 21 14 1 3)2 2) 1 1) 1 1
6- 15 Mu 5 2 3 5 5} 4 1 3/4 4
Si 6 2 45 1 43 3} 1 1 2 2
Nu 3 2 1 4 1 3/2 2| 3 3| 6 6
Rt A 2. 21:2 2 1 1
16- 25 ie 3 2 1 1 1) 1 1 3 3
sf
Nu 1 1 1 1 2 2
Ri 2 1 1 1 1j1 1 1 1
26- 35 Mu 7 & @ 1 1
Nu Zz 2 i
36- 45 Mu 2 1 1 1 1
Nu 11 1 11 1
46- 55 Mu 4 2 2 1 1 1 1
Nu 1 A 1 1) 1 1
56- 65 Mu 3 3 1 oil
Nu 1 1
66- 75 Mu 1 172 1 1
Nu 1 1
76- 85 Mu 2 1 Wi 1| 2 2) 1 1 1 1
Nu
86- 95 Mu 2 1 1 1 1
Nu
96-105 Mu
Nu
106-115 Mu 1 1
Nu
116-125 Mu
Nu
Totals IB....... 101 49 52;9 2 7/25 9 1622 6 16/7 1 615 1 14
Totals IIB....... 53 22 3117 1 618 5 13/16 3 13/12 2 10115 2 13
Total number of entrances into cul de sacs, IB, 135 44
Total number of entrances into cui de sacs, IIB, 78 43
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 17
TABLE I—Continued
GENERAL SUMMARY OF RESULTS IN THE B-MAZES
Blind alley....... Seventh
Eighth
DORTOB es irecnestens Adare Compl. Half Start.
Compl.
Half
Start.
Direction......... E R RE R FE R
E R F
E R
Runs Group
1- 2 Mu IB
oy
J
CO mt bo
to
et het
13 7
3
14 232 1
3
Nm
19
9
18
5
RHO
—_—
NNR DS bho et
NNr LO
ie)
Y
—
ies]
Bmw Oo | OMNYW | HOR me
ioe
Aye] wowN |] He
A Al Hw i
A alHew
wl] ARO !]WmwO
to
bo] mt eH
—_
—_
SD RRNN] WWNW
16- 25 Mu
rs
ES
w
w
SED NN] WHEN d
me | TOM
-—
fet et
po
—
26- 35 Mu
— bn
me
=
ee
36- 45 Mu 2 2
Pw wo» -
Pw Oe Lael
mH
46- 55 Mu 1 1 1 1
56- 65 Mu
66- 75 Mu
76- 85 Mu
86- 95 Mu
96-105 Mu
106-115 Mu
116-125 Mu
Totals IB....... 22 3 «19)13 13/23
Totals IIB....... 15 1 14/11 11]13
1
3
22
10
42 11 31
26 4 22
g100
Total number of entrances into cul de sacs, IB,
Total number of entrances into czl de sacs, IIB,
58
39
18 JOSEPH PETERSON
TABLE I—Continued
GENERAL SUMMARY OF RESULTS IN THE B-MAZES
Blind alley....... Ninth Tenth
Degree........... Compl. Half Start. | Compl. | Half | Start.
Direction......... E R FE R F|E R FIE R FIE R FIE R
F
_
NPRwWN
_
am
Z
ay
oS
=
i
Obwolwomuw
Ww
a
=
om!
ee)
OR RO] WON
= bh
ll ee ee
et ee | et
w Bw N ale)
w
nH
PPT NOHO | NNW
mee | WNTOTCT
Z
~
a
mt
_
>
o
uo
s
i
i
_
=
96-105 Mu
106-115 Mz
116-125 Mu
Totals IB....... 15 1 14) 6 6/10 10/27) 3 24) 4
Totals IIB....... 21 26 1 52 1 1182 4 8/5
ou
a
~
Total number of entrances into cul de sacs, IB, 31
Total numher of entrances into cz! de sacs, IIB, 39
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 19
TABLE II
GENERAL SUMMARY OF RESULTS IN THE A-MAzES
Blind alley....... First Second
Degree of entrance] Compl. Half Start. Compl. Half Start.
Direction......... E E E E R FE R FE R F
Runs Group
1- 2 Ru 15 3 6 3 2 11 1 14°45 9
TA, Ni 10 1 2 5 SS. De dhs oh. 2
Mt, 1 1 1 1 1 1
Su alg 2 2 4 3 12 2 1 1
IIA, Nt, 5 Z 2 2) 1 11 1
Mt 2 1 1 1} 2 2
1- 5 Ru 22 4 9 10 3 73 2 118 5 13
Ni 13 4 4 8 2 64 2 233 1 2
Mi 3 1 1 9 6 31 i
Su 30 3 2 10 6 44 3 #25 5
Netz 8 4 2 2) 2 2| 3 3
Mt, 3 3 ak yl 1
6- 15 Ru 14 6 2 134 94 #1 3/13 13
Nt 3 2 2 2 1 13 1 24 1 3
Mt, 5 2 1 10 6 43 3| 2 2
Su 2 4 3 2 1 14 4! 3 3
Nin 2 1 2 2 1 2
Mt 1
16- 25 Ra 4 4 4 1 1; 3 3
Nu 1 1 i) io Se, ia, et
Mi, 1 4 1 35 5
Su 2 6 6
Nit
Mt
26- 35 Ru 3 4 1 1 1
Ni 1 1
Mt 1 1
Su 8 1 ej at 4 4
36-45 Ru 2 1 1
Su
46- 55 Ru 1 1
Su
56- 65 Ru
Su
Totals IA....... 68 29 20 59 28 31/27 9 18/51 8 43
Totals ITA....... 45 20 9. 15 8 711 3 824 1 23
Total number of entrances into cul de sacs, IA, 117 137
Total number of entrances into cul de sacs, IIA, 74 50
20
JOSEPH PETERSON
TABLE Il—Continued
GENERAL SUMMARY OF RESULTS IN THE A-MAZES
Blind alley....... Third Fourth
Degree of entrance! Compl. Half Start. Compl. Half Start.
Direction......... E R FE R FE R FE R FE R FE R F
Runs Group
1- 2 Ru | 4 1 3 6 3 312 8 4 2 2 7 § 2
TAJN | 3 1 2 2 1 #115 9 6
Mi}1 1 1 1) 1 14 1 3
Su | 2 2 3 1 2
IIASNé | 1 1 1 WS 2 32 dT 32 2
Mr | 1 1 a} 1 1 1
1-5 Ru |6 1 5 7 3 #414 9 553 5 11 6 5
Nh |}6 2 4 3 1 218 9 93 1 23 3
Mi }8 6 22 2); 2 2110 1 91 #1 1 1
Su |7 3 4 2 212 6 6/3 1 2/5 1 4
Nb | 2 2) 1 1} 3 3}5 2 3/2 1 1/2 2
Miz | 1 1 1 1 2 2
6-15 Ru 15 6 95 5) 4 420 11 93 1 #22 2
Ni | 7 2 5/5 5) 4 4.6 1 51 1) 6 6
Mi 10 3 7 2 2) 1 17 2 51 1] 6 6
Su |6 3 3/6 6 1 U8 3 54 4] 8 8
Ni | 1 1 5 5) 1 11 14 1 38
Mi | 1 1
16-25 Ru /}/5 1 45 5] 6 67 1 62 1 1/6 6
Na |3 2 1 1 1 6 6
Mi/1 1 6 664 1 3/1 1 1 1 1 1
Su | 1 175 1 = 4{10 10 2 2| 4 4
Nie 2 2 1 1
Mi,
26-35 Ru 3 4 4| 4 441 1 3 3
Nt
Mi, 2 2}2 1 1 1 1
Sue |5 3 21 1] 8 8) 1 1| 4 4| 6 6
36-45 Ru {3 1 2,4 4\ 4 4 1 1) 1 1
Su at 1j1 1 8 8
46-55 Ru 1 1) 1 1] 3 3) 1 1} 1 1
Su | 1 1 1.) a 3 3
56-65 Ru
Su 1 1
Totals IA....... 64 25 39/35 35/43 6 37/90 35 55/21 11 10147 6 41
Totals IIA....... 25 10 15|14 1 13/33 33/28 12.1618 2 1642 2 40
Total number of entrances into cul de sacs, IA, 142 158
Total number of entrances into cul de sacs, ILA, 72 88
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 21
TABLE II—Continued
GENERAL SUMMARY OF RESULTS IN THE A-MAZES
Blind alley....... Fifth
Degree of entrance! Compl. Half Start. — Start.
Direction......... E R FE R FE R lin R F
Runs Group
1- 2 Ru 4 3
TA, Ni, 6 3 3
Mi, 1 1
Su | 2 2| 1 1) a 2 2
ITA, Nin 2 2 2 2 1 1
Mi 1 1
1-5 Ru 10 0| 1 1 4
Nt 9 7|4 4
Mt, 1 1
Su | 3 3) 6 6| 2 2) 8 8
Ni a 2, 2 2 1 1
Miz 1 1
6-15 Ru | 3 3) 3 3) 4 4 1
Nt, | 1 1 1
Mi,
Su | 4 442 1 1/2
Nt | 1 1
Mt
16-25 Ru 1 11
Ni
Mh,
Su
Ni
Mt
26-35 Ru | 1 1 1
Nt
Mt
Su
36-45 Ru 1
Su
46-55 Ru | 1 1
Su {1 1 1 1
56-65 Ru
Su
Totals IA....... 6 6) 4 4|26 6 6
Totals ITA....... 9 910 1 95 3 3
Total number of entrances into cul de sacs, IA, 18
Total number of entrances into cz de sacs, IIA, 17
22 JOSEPH PETERSON
RESULTS
Tables I and II give in a condensed form the main results
of the entire experiment. In the separate larger divisions are
given the reactions to the several blind alleys. These reactions
are classified in a manner most easily made clear by taking
up a concrete case. In table I the words “ First,” ‘“‘ Second,”
etc. at the top stand for the blind alleys of the B-mazes of the
corresponding numbers. The results of the first blind alley, for
example, are then divided into three parts, ‘‘ Complete,”’ ‘‘ Half,”’
and ‘ Start,” meant to designate the degree of entrance by
the rats into the blind alleys, as already explained. Complete
entrance means going entirely to the end of the blind alley,
or so near the end that the animal might reach the end by means
of the vibrissae. Frequently the rats ran against the end with
considerable force. Half entrance means approximately half
way, or all entrances between complete and beginning. Those
marked ‘‘ Start ’’ include cases in which the animal either just
put the head in or entered with the fore half of the body. In
such cases the hind feet of the animal usually remained in the
true path, so that the general orientation was not completely
given up as in the other two cases. The three columns coming
again under each of these rubrics show respectively, the number
of entrances into the blind alley in question, E, the number
of returns toward the place of starting in the maze on the rats’
emerging from the blind alley, R, and the number of times the
animals kept the general orientation, 7. e., continued toward
the food box, F. The totals for R and F must therefore equal
the number under E.
The figures in the left column of the table indicate the number
of the run, or of the test, of the animals, while the letters Mu,
St, etc. stand for the group, as Group M untrained, Group S
trained, and so on. The description of each group and of its
practice distributions are given in detail in the schedule, pages 9
and 10,.to which frequent reference is advisable. Now, to illus-
trate in a concrete case, in the first line of the data, giving results
of the first two trials of the animals, we find that Group Mu
(eight rats, untrained, running in Maze IB) made nineteen
complete entrances into the blind alley No. 1, with ten returns
and nine cases in which the rat continued forward toward the
food box. There were two entrances half way, with two forward
tuns and no returns; thirteen beginning entrances, with four
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 23
returns and eight cases of the animal keeping its general forward
orientation; and so on, through the results for all the blind
alleys in order.
Note that the figures for groups Mu and St are in bold face
for blind alley 1, and not for 2, and that these relations are just
reversed for the groups of animals running in Maze JIB. The
bold face designates full length cul de sacs, and the figures not in
bold face indicate that the blind alley was shortened. The amount
of shortening in any case is shown in figure I, as already explained.
Careful attention to all these matters will greatly aid the reader
in getting quickly and conveniently the general results of
numerous reactions. Without such attention the tables are
meaningless. The results cannot so well be effectively and
accurately shown in graphs.
The totals at the foot of the columns must not be taken too
seriously, as will be evident in subsequent discussion. These
are totals only of changing comparative quantities. For this
reason the results of the experiments have been classified for
different periods of the training. The results of the first two
trials are given separately—and are not added in the totals
because they are again included in the data for the 1st to Sth
trials—as they are least affected by the animals progressive
training. They show us approximately whether mere chance,
or probability laws, can explain the direction that an animal
beginning in the maze takes on emerging from a cul de sac,
whether it returns or continues forward keeping its general
orientation,—not accurately, however, for learning begins from
the very first experiences in the maze. The progression of the
learning in the case of each particular cul de sac is shown by a
gradual decrease in entrances in the summaries of the Ist to
5th, the 6th to 15th, 16th to 25th, etc. trials; also by the gradual
decrease in returns and the increase, correspondingly, in the
number of cases of keeping the general forward orientation.
These two kinds of changes are very interesting and illuminating
toward showing, in a manner not hitherto done with data on
learning, just how the cul de sacs are eventually eliminated."
This is our main concern in this paper.
“4 Professor Carr has pointed out that the extent of entrance to cul de_sacs grad-
ually decreases, as well as the number of entrances. (Hicks, V. C., and Carr, H. A.
Human Reactions in a Maze. Jour. Animal Behav., 1912, 2, 98-125. See par-
ticularly page 116.)
24 JOSEPH PETERSON
Three important features of the results are to be noted. The
first is the rapid decrease in the proportion of the returns to
forward runs, on the rat’s emergence from blind alleys. With
the exception of blind alleys 2 and 5 in the B-mazes few such
returns were made after the 15th trial, though the animals
continued to enter some of the blind alleys beyond the 75th,
some even beyond the 100th. These cul de sacs, noted as
AVERAGE PER TRIAL PERIOD 8p
4-5 6-15 16-25 26-35 46-55 66-75
TRIAL PERIODS
as
7 a
“ts.
‘ 1 A 1 : t
1-5 6-15 16-25 36-45 56-65 76-85
TRIAL PERIODS :
L
96-105 116-125
FicuRES II AND III.—CE is the curve of decrease in average number of complete
entrances per trial to Blind Alley 1 full length, Maze IB; R indicates the
decrease in returns, and 2R twice the returns, from this cul de sac. C’E’, R’
and 2R’ show corresponding data for Blind Alley 1 shortened, Maze IIB.
Eight untrained rats in each case.
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 25
exceptions, have directions such as to favor returns in the case
of a rat emerging from them. This more rapid decrease in
returns than in entrances to cul de sacs is least complicated,
and also shown most emphatically, in the case of the complete
entrances to cul de sac 1, which is encountered before the rat
could be confused by running into any other blind alleys. Figure
II shows the matter graphically. Curve CE represents the
number of complete entrances of eight untrained rats to the
first blind alley at full length, as in Maze IB;. curve R, the
returns; and 2R, twice the returns. 2R is a better curve for
comparison with CE because originally, 1. ¢. before an animal
is at all practiced, about half of the entrances are followed by
returns; twice the returns, therefore, gives a number initially
about equal to the total number of entrances. Figure III gives
corresponding curves, C’E’, and 2R’, respectively, for the same
number (eight) of untrained rats in cul de sac 1, shortened from
22 inches to 8.5 inches. Here the same result is evident: while
the elimination of entrances is far more rapid than in the case
of the longer blind alley, the returns are still more rapidly reduced
as shown by the 2R’ curve.
It may also be noted here under our first point that the
returns in both the B-mazes persisted longer in the cases of the
blind alleys farther from the food box than of those near it.
That is, returns from blind alleys first encountered were less
easily eliminated, as were also entrances, than from those further
along the true path. This is true even in cases of blind alleys
nearer the food box that were comparatively long, as 7 and 8,
even though, as in the case of 8, the direction of movement
in emerging from the cul de sac favored returns. It is barely
possible that an odor factor may have entered in case of 8.
The mazes IA and IIA are not so well adapted to show these
relationships, as there are fewer blind alleys of various individual
differences of complexity, but the same conclusions as those
given for the B-mazes may also be made for them.
A second important point to note is, that the nature of the
response to a blind alley gradually changes with practice, as
well as the relative number of entrances into it. This change
in the nature of the response is more marked in longer than in
shorter blind alleys, particularly in those whose elimination was
most difficult. It is illustrated best in the data from cul de sac
26 JOSEPH PETERSON
1 of Maze IB. Many of the entrances to 2, as the observation
of the animals in their responses and also their individual records
showed, are clearly due to confusions resulting from entrances
to 1. The experimental notes supply many evidences. As a
rule the rat in the early stages of response to such a blind alley
runs rapidly into it the entire distance, usually coming into
AVERAGE PER
TRIAL PERIOD
1 J FT =
1-8 98-15 16-25 56-45 56-85 76-85
TRIAL PERIODS
: i 1
36-45 66-65 76-85 96-105 116-125
TRIAL PERIODS
a 1 i
1-5 6-15 16-285
FIGURES IV AND V.—C shows decrease in average number of’ complete entrances
per trial to Blind Alley 1 full length in the B-mazes; H arnt for half-way
entrances, and S for beginning entrances. C’, H’, and S’ show corresponding
results for the blind alley shortened. Eight untrained rats in each case.
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 27
contact one way or another with the end; but with succeeding
trials the entrance is less and less complete, until finally the
impulse to enter is wholly inhibited. Thus in the records of
responses of two groups each of eight untrained rats to the first
blind alley in the B-mazes (table I) the large numbers in the
E-columns shift gradually from the ‘“‘ Complete’’ through the
“Half” to the “ Start’? column. This shift is graphically
shown in figure IV and figure V for first blind alley of mazes
IB and IIB, respectively. C and C’ are the curves representing
the rate of elimination of complete entrances, H and H’ of half
entrances, and S and S’ of beginning entrances. Note that
while the C-curves fall rapidly from the first, especially the
one (C’) from the shortened cul de sac, there is a decided rise
in the H- and the S-curves. Specifically, in the case of Maze
IB (the cul de sac long), C falls gradually, with two minor excep-
tions, all the way at a nearly uniform rate; H rises almost
uniformly to the 35th trial, then it keeps almost a uniform
height to the 65th trial, and finally gradually declines; and S,
after a rapid initial decline, gradually rises again until the 65th
trial is reached, when it gradually declines and reaches zero
before the other two curves. In the case of Maze IIB (cul de
sac shortened) the same relationship between these respective
curves is shown, though all these curves drop earlier in the
process than with the longer blind alley, except that in this
case the S’ curve holds out longer than either of the other curves.
A cursory examination of the data for other blind alley records
shows that this type of transition from complete to only partial
entrance and then to final elimination is a general feature of the
results for the different groups of animals in the various mazes.
A few exceptions only, in cases of very short cul de sacs, are
noticeable. This is a phenomenon of learning in the maze to
which little attention has previously been given, and which
seems to the writer to be inexplicable on the basis of mere fre-
quency and recency-laws. Several impulses working together,
some facilitating others inhibiting one another, gradually result
in the survival of the most consistent, or complete acts. No
hesitancies in the rats’ behavior in these cases were present,
such as might be secured from persons in similar circumstances.
The rats evidently did not have time, nor adequate sense organs
and conscious memories as a person would have, to recognize
28 JOSEPH PETERSON
and take note of external stimuli, but resembled automatic
machines in the quickness and uniformity of their responses.
This change appears more significantly in the results of most
of the individuals than in those of all averaged. Here are some
examples. Rat 18, of Group Mu made entrances to the first
blind alley (full length) in this order: 12c (complete), th (half),
1c, th, 5c, 1s (started), 4c, th, 2c, th, 5c, ih, 4c, th, Ic, 4h,
2c, 3h, 3s, 1c, lh (total 55 entrances). Rat 10’s record, same
group, is Is, 1c, 1h, 9c, 1h, 7c, 2h, 3c, th, 1c, 2h, 1s, 2c, 1s, 2c,
th, 1s, 1c, lh, 2c, 1h, 1c, 1h, 1c, 1h, 1c, 3h, 1s, 1c; the next time
on passing this cul de sac there was a momentary pause with
three very rapid in and forward vibrations of the head, causing
a confusion in which the animal made eleven errors in the other
nine cul de sacs none of which it had entered, with but one
exception, for twelve trials; then 1s, 2c, 1s, 2c (after another
such vibrating pause before the cul de sac), 2s, 1c, th, 1s, 2c,
lh, 1c, th, 1c, 1s (total 70 entrances). These results are typical.
In numerous cases when the habit of avoiding the cul de sac
was nearly complete, so that the animal usually made the ‘“‘s”
type of entrance, the peculiar rapid vibration of the head noted
above took place. The pause was, however, but for an instant.
This response seems to indicate that the impulse to go forward
at the critical place is still partly checked or impeded by one
to enter, not quite eliminated. It is important to note, more-
over, that when finally the rat does succeed in passing the cul
de sac, even when this hesitant, vibrating behavior does not
take place, it very frequently runs headlong into some neighbor-
ing cul de sac which had long since been inhibited, and thereby
gets considerably confused. Frequently, after such an experience
it makes a complete entrance into the cul de sac in question the
next trial, just as a child “ speaking a piece’ must bow again
and start over when she goes wrong. This is one reason why
a few complete entrances continue to occur. More than once
an animal which had successfully passed cul de sac 1 for several
trials would, without any hesitancy, run into it with great speed
and against the closed end with terrific impact. In one such
case the animal’s whole maze habit, just on the finishing stage,
seemed to have been temporarily jolted wholly out of gear, its
next trial being much like that of a beginner. All this makes
it very plain that maze habits are not to be explained on the
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 29
basis of individual, disparate “‘ acts,” following in their occurrence
some law of chance. On the contrary, the various impulses
in the random activity of the early trials are gradually and
collectively woven into one matrix of successive responses, each
setting off the next succeeding one, and all shaped by the whole
\s ~%R MD
in tom am
SE
Pm woh
wey
o 6 8 /0
EYS t
T
J
|
MTs Bes BO a0
/ 20 3 4 7 a
BLIND ALL
FIGURE VI.—Heavy columns, double lines, single lines, and discontinuous lines
show, respectively, total entrances by all animals to full length and shortened
blind alleys in the B-mazes, and to full length and shortened blind alleys in
the A-mazes. Figures above columns give the totals represented.
30 JOSEPH PETERSON
circumstance of the maze environment.'® This seems to imply
that the effect of one stimulus holds over into and conditions
effects of later stimuli.
The third point to note in our results is that when any given
cul de sac is shortened it is eliminated more readily than when
left at full length. That is to say, other things equal, and
within certain limits, a long cul de sac is eliminated less readily
than a short one. This statement is amply borne out in our
data both from the A- and the B-mazes. The general results
of all our experiments are shown roughly in the accompanying
diagram, figure VI, representing the total number of entrances
to each of the blind alleys in the various mazes. The heavy
black columns and the double lines represent the totals for
the full length and the shortened blind alleys, respectively, in
the B-mazes; the single continuous and the broken lines stand
for the corresponding totals for the A-maze blind alleys. In
the B-mazes the total entrances to the full length cul de sacs
is 1311, while the total number of entrances to the same cul
de sacs when shortened, by an equal number of animals under
the same conditions, is 929, a decrease of 29%. This decrease
would doubtless be considerably greater but for the fact that
confusions by the long blind alleys resulted in random behavior
which increased the totals for the shortened cul de sacs. For
instance, table I shows that more entrances were made into 2
short than into 2 full length. This was very clearly due to
the fact that as long as the habit to avoid 1 was incomplete
the animals in the confusion also entered 2. It will be recalled
that in the A-mazes the cul de sacs were all full length in the
one and all shortened to about half their length in the other case.
Here we do not have the confusion noted in the B-mazes. The
shortened blind alleys were entered 47% fewer times than those
of full length. This bears out the conclusions drawn from the
B-mazes.
The effect of shortening the cul de sacs was most noticeable
in the case of 1 in the B-mazes, which was by all means the most
difficult to eliminate. Being the first to encounter, it was
16 On this point our results agree with some aspects of those by Peckstein, L. A.
Whole vs. Part Methods in Motor Learning: a comparative Study. Psych. Mon.,
Ser. No. 99, 1917. ‘‘ Each aspect of the course is no doubt associated with and
located in reference to all the details of the course and to the entire objective en-
vironment as well.” P. 30.
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 31
likely the least complicated by the results of entering other
blind alleys. Table III and figure VII show comparatively the
rate of elimination of all entrances to this cul de sac full length
and shortened, 22 and 8.5 inches respectively, by the two groups
of rats, Mu and Nu. While the two curves start near together
the one, 5, representing the entrances to the shortened cul de sac
drops rapidly after the 15th trial; the other one, L, after the
initial decline keeps nearly the same height to the 55th trial.
The percentage eliminations are shown for the long and for
the shortened cul de sac, respectively, by curves E and E’.
TABLE III
ELIMINATION OF ALL ENTRANCES TO BLIND ALLEY 1. Two GROUPS OF
EIGHT Rats EacH. Mazes IB ann IIB
Wilalsuisi)datacdieayaees 1-2 1-5 6-15 | 16-25 26-35 | 36-45 | 46-55
Av. No. of entrances to |
blind alley 1, long...| 16.5) 11.1 The HEB 6.6 6.4 6.0
Percent wovac ees deen es 100.0 | 67.3 | 46.6} 47.3 | 40.0] 38.8) 36.4
Av. No. of entrances to
blind alley 1, short’d.| 13.0 8.8 7.2 4.1 1.8 1.1 1.1
POP COM Gaia scarier as iso 100.0 | 67.7 | 55.4] 30.8] 13.8 8.5 8.5
TABLE IlI—Continued
ELIMINATION OF ALL ENTRANCES TO BLIND ALLEY 1. Two Grours or
Eicut Rats EacH. Mazes IB ann IIB
(ENaIS. osc ce Sees 56-65 | 66-75 | 76-85 | 86-95 | 96-105 106-115]116-125
Av. No. of entrances to
blind alley 1, long... 5.0 3.5 2.5 8 6 6
a a ee es | 22) 2) 428| @8| 8.6] ©
Av. No. of entrances to |
blind alley, 1 short’d. a2 | al 0) 0 0 0
Per cent...........05. 1.2 8 s/o | 0 0 0
The results from cul de sac 2 are 221 entrances to the full
length (40 inches) and 234 to the shortened form. This would
appear to contradict our general conclusion. However, it must
be remembered that the rats for which 2 was shortened made
3
32 JOSEPH PETERSON
346 more entrances to 1 (long) than did the control animals
for which 2 was left full length; they also made 18 more returns
to the starting place in the maze. This not only required that
2 shortened be passed more times than 2 long, but also with
greater probability of entrance for each time. It was noted
that rats entering 1 were likely thereby to be thrown out of
Per Av. number
Cent Per Period
100
90
BO ALG)
70
60
50
4or8 NALA,
30
20
Lo
e
1 1 L uz. i
1-2 1-5 6-15 16-25 36-45 56-65 76-85 96
- -1L05 116-125
TRIAL PERIODS
FIGURE VII.—L shows rate of elimination of all entrances to cul de sac 1 long,
Maze IB, and S same for 1 short, Maze IIB. E’ and E show corresponding
percentage eliminations.
orientation and to make other errors. There can therefore be
little doubt that if 2 had been the only blind alley in the maze,
it would have formed no exception to the general rule. The
greater number of entrances to 4 shortened than to 4 long
(86 to 69) is due to the fact that rats emerging from 5 had a
strong tendency to run into 4. A glance at the maze will show
why this is to be expected. There were 32 more returns from
5 long than from 5 short; furthermore, entrance to 5 long had
the greater tendency to disorient the animal so that entrance
to 4 would be an increased probability. Just why 8 short
should have been entered 51% more than 8 long is not easy to
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 33
determine. There were, moreover, 14% more returns from the
entrances in the former than in the latter case. It is possible
that the rats entering 8 at full length, which runs along side
the food box, had time and opportunity to get sufficient odor
from the food to influence them against returning. Accidental
factors may have been the cause in part; half of the entrances
were made in the first two trials, and the total numbers are
too small to indicate with much probability the actual trends.
On the whole there can be no question that, other things
equal, entrances to short cul de sacs are more easily eliminated
than entrances to long ones.
The results from both types of mazes used in this experiment
(see tables I and II) show that on the whole cul de sacs first
encountered in the maze were entered more frequently, and
that the impulses to enter them were overcome with more
difficulty, than were those occurring further along the true
path, or nearer the food. In this respect our results are in
agreement with those of Miss Vincent'* and contrary to those
of Miss Hubbert.17 While in the present experiment, ‘not
intended especially to test this point, the bearing of the results
is necessarily complicated by an inequality of the lengths of
the various blind alleys, there is no evidence to show that results
would have been different with cul de sacs of equal lengths and
of equal direction difficulties. In the B-mazes, for example,
‘6 and 7 were much less troublesome than 3 and 4, in many
respects similarly located with respect to the correct path, and
all of equal length. By all means the most difficult cul de sac
to avoid entering was 1, even when shortened to 8.5 inches.
The total entrances to 6 and 7 long are 101, against 142 to
3 and 4 long; to 6 and 7 shortened 83, against 130 to 3 and 4
shortened. The total number of entrances to 1 short are 275,
whereas the totals to 6, 7, 8, 9, 10 full length amount only to
192. It seemed that the rats got rather firmly registered in
their proprio-ceptive system of controls the tendency to make
two successive turns of 90 degrees each to the right, beginning
16 Vincent, Stella B. The White Rat and the Maze Problem—IV. The Number
and Distribution of Errors: a Comparative Study. Jour. Animal Behav., 1915,
5, 367-374. “‘ The final members of the cul de sacs were entered less frequently
and eliminated first.” P, 374.
17 Hubbert, Helen B. Elimination of Errors in the Maze. Jour. Animal Behav.,
1915, 5, 66-72.
34 JOSEPH PETERSON
at the corner of the maze before cul de sac 1, and that since the
turns were so close together they tended very persistently to
fuse together into a single turn of 180 degrees, thus taking the
rat into the blind alley. It was very interesting to see certain
rats continue to run into 1 with almost monotonous regularity
for three weeks, three trials each day, while other errors, errors
of entering other cul de sacs, occurred very seldom. Thus from
the 10th to the 79th trial, inclusive, rat 9 made 60 errors of
entering 1 with only 11 entrances to all the other nine blind
alleys; rat 11 from the 24th to the 83rd trials made corresponding
errors of 47 to 15.
In the A-mazes cul de sacs 5 and 6 were likewise entered
fewer times and eliminated more easily than 1, 2, and 3, all
of length equal to that of 5 and shorter than 6. It is, of course,
not contended here that the two sets of blind alleys compared
are of equal difficulty in all respects other than that here con-
sidered. At the same time, they may be approximately equal;
that is a matter which can be determined only empirically.
The accompanying table (table IV) shows that not only is
the number of entrances to blind alleys first to be passed along
the true path greater than that nearer the food box, but also
that the percentage rate of elimination is greater in the latter.
This is shown by comparing the number of entrances to the
different groups of cul de sacs in question for different successive
periods in the learning process from the first to the last trial.
In the first five trials of all the animals, trained and untrained,
the average number of entrances per trial into cul de sacs 1-4
of the B-mazes is twice that of entrances into 6-10. Calling
these numbers for the first period (the average of the Ist to the
Sth trial) 100% each, to get a common basis for comparison,
we find that there is a much more rapid percentage drop of elim-
ination of entrances in the case of the blind alleys nearer the
food box. Since the trained rats discontinued the experiment
with the 25th trial without finishing the habit, the percentages
for the two groups in the B-mazes are not correct after the
25th trial, though they are strictly comparable. An additional
line is given, in the case of each of these groups, of the accurate
percentages of elimination of entrances for the untrained rats
(eight in each group) alone. It will be noted that in the case
of the five cul de sacs nearest to the food box the percentage
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 35
of elimination is considerably more rapid than in that of the
first four blind alleys encountered. In the case of the A-mazes
the percentage elimination is considerably greater for cul de
sacs § and 6 than for 2 and 3. Figures VIII and IX represent
graphically the data of Table IV.
There is no room to doubt that the blind alleys first to be
passed along the true paths in the mazes used are both more
frequently entered and more slowly eliminated than are those
further along the trail.
TABLE IV
Periods of trials............... 1-5 6-15 | 16-25 | 26-35 | 36-45 | 46-55
Blind alley 1............... 134 210 166 84 75 71
Blind alley 2............... 147 76 68 39 33 24
cn Blind alley 3............... 79 11 5 6 2 7
| Blind alley 4............... 89 16 19 8 6 6
N
wy | Totals: i<e stgauuviar caved 449; 313] 258} 137, 116] 108
© Av. per trial. cases on ona 89.8] 31.3] 25.8] 13.7] 11.6] 10.8
‘Per cent, 24 rats............] 100.0 | 34.7] 28.6] 15.2] 12.9] 12.0
(Per cent, 16 untr’d rats... .. 100.0 | 27.6] 25.5}; 19.7] 16. 15.6
Blind alley 6.............. 42 28 9 1 2 2
Blind alley 7.............. 28 33 18 10 6 2
Blind alley 8.............. 62 15 5 3 2 3
om |Blind alley 9.............. 49 7 4 5 3 2
g )Blind alley 10.............. 36 14 3 1 1 1
GI
Bi | TVORALS: oe eesed vaaws yeaa nas 217 97 39 20 14 10
Av. per trial..........0.... 43.7 9.7 3.9 2.0 1.4 1.0
Per cent, 24 rats............ 100.0 | 21.3 9.0 4.6 3.2 2.3
Per cent, 16 untr’d rats. ....| 100.0 15.6 6.8 4.0 2.8 2.0
(Blind alley 2............... 84 65 28 8 3 1
< | Blind alley 3............... 51 73 49 25 13 3
s SPO CALS 2s. ccseriac: saw aaselta 135 138 77 33 16 4
=& |Av. per trial..........0.... 27.0} 13.8 7.7 33. 1.6 4
bPeF CONC. 3s suee cies de anione 100.0} 46.9] 26.5] 11.2 5.6 1.4
Blind alley 5............... 32 21 2 1 1 3
< |Blind alley 6............... 23 9 0 2 0 1
vo
& )Totals......0.. 0. cece eee eee 55 30 2 3 1 4
& | Av. per trial.......0.00.... 11.0] 3.0 2 3 il 4
Per CEN ic aicardiun ere naters<| 100.0) 23 1.8 Dk 9 3.6
36 JOSEPH PETERSON
TABLE IV—Conlinued
Period of trials........ 56-65 | 66-75 | 76-85 | 86-95 | 96-105 |106-115)116-125
Blind alley 1....... 52 36 26 8 q 6 0)
Blind alley 2....... 15 10 8 7 2 3 3
oc Blind alley 3....... 1 2 1 2 1 0) 0
» | Blind alley 4....... 6 2 4 2 0 0 0)
N
S| Totals encase wesc uns 74 50 39 19 10 9 3
| Ave per trials sassei.ce 7.4 5.0 3.9 1.9 1.0 9 33
Per cent, 24 rats.... 8.2 5.6 4.3 Dek 1.1 1.0 13)
{Per ct.,16 untr’d rats} 10.6 7.2 5.6 27 1.4 1.3 4
Blind alley 6...... 1 0 1 1 0 0 0)
Blind alley 7...... 0 0 0) (0) 0) 0 0
Blind alley 8...... 0 1 0 2 0 0 0
fQ|Blind alley 9...... 0 0 0 0 0 0) 0
@ |Blind alley 10...... 0 0 0 1 0 0 0)
i)
= |Totals............. 1 1 1 4 0 0 0
Av. per trial........ 1 i eal A 1) 6 0
Per cent, 24 rats.... “y my) gh 9 0) 0 0)
Per ct.,16 untr’d rats 2 22, 4 8 0 0 0
It may be that the odor of the food is a factor that at least
partly explains the more easy elimination of the cul de sacs
nearer the food box. However, there is very little, if any, real
evidence that such is the case. A crucial test would be to use
anosmic rats, though other means of controlling the odor factor
are easily possible. Some facts in the present experiment count
against the influence of odor as suggested. For example, errors
of entrance into cul de sac 10 are nearly as numerous as those
of entrance into 9, although to get to 10 the animal had to pass
a short alley of 8.5 inches leading directly into the food box.
Moreover, all the rats, with occasional exceptions,'* ran so
rapidly after the first trial that it is improbable that food odor
had any immediate direct influence in the behavior in the maze.
There was no evidence in the behavior of the animals that they
were attracted to the food box by such odors.1® In the cases
of supposed trailing, already noted, the animal which appeared
18 Occasionally, without any apparent external condition to explain the behavior,
an animal would sneak slowly and cautiously all the way through the maze. In
a few cases such activity seemed to be due to recent fights with other rats or to
noises from fights between other animals.
_1* An exception should be made here of the case of returns from cul de sac 8, already
discussed. The floor of the food box was covered with paper (double thickness)
during the feeding each day, and during the experiment the food was kept in a
dish in the extreme corner of the food box away from cul de sacs 8, 9, and 10.
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 37
to be following a scent of any kind moved perceptibly more
slowly, holding the nose continuously or frequently to the floor.
The writer does not believe that the more rapid elimination of
the cul de sacs nearer the food is to be explained on the basis
of scenting the food. The matter, however, needs further test.
Per Cent
100
80
80
Per Cent 7
1006
Bo
sot
ro bh
6OL \
Sor
\
nes <~
Qee LF Se
1-5 6-15 16-25 36-45 56-65
TRIAL PERIODS
40>
30+
20 +
“| . Ser see had, tee an Fig. V1.
1-5 6-15 16-25 36-45 66-65 76-85 86-105 116-125
TRIAL PERIODS
FicuRES VIII AND IX.—F and L show percentage elimination of all entrances to
cul de sacs 1-4 and 6-19 combined, respectively, by twenty-four rats in the
B-mazes; UF and UL the corresponding data for sixteen untrained rats. F’
and L’ show the percentage elimination, respectively, of all entrances to blind
alleys 2 and 3, and 5 and 6 combined, by twenty-two rats in the A-mazes.
Do pure probability laws govern the returns of the rat on
emergence from blind alleys? In the tables of results (tables I
and II) the totals of the first two trials have been kept separate
so that the percentage of returns from blind alleys toward the
starting place in the maze could be found for a period little
38 JOSEPH PETERSON
influenced by the effects of training. The following table (table
V) classifies for easy comparison the results of all the rats on
the first two trials. The entrances to cul de sac 1 in the A-
mazes are not included as all emergences from this blind alley
brought the rat to the place of the entrance to the maze.
TABLE V
Full Length Cul De Sacs
Compl. Ent. | Half Ent. Start. Ent. ne
et.
Rats Maze of all
E’s.
Ent. | Ret. | Ent. | Ret. | Ent. | Ret.
Set dis omer anucctiis s B 170 76 35 6 54 16 38
AAT Ce sicn tte se 4 eae 8 B 44 16 Cd 0 | 14 3 29
4amte’d s ven eisay ane y A 51 24 @ 4 46 16 42
i Gh aca s (arene mene A 33 13 5 2 12 3 36
|
Average per cent returns.........0.0.00 000. c ccc eee eens 33.75
TABLE V—Continued
Shortened Cil De Sacs
Compl. Ent. | Half Ent. Start. Ent. 8
Rats Maze Ret.
of all
Ent. | Ret. | Ent. | Ret. | Ent. | Ret. E’s.
8 UTE nasa econ B 182 72 27 11 48 18 39
BEE Cove cson loess crreae B 42 13 4 2 20 5 30
A TCE Cision saunas A 23 10 6 3 12 0 32
A ALE: Cictatten chines itae htt A 1l 2 6 1 10 0 ll
Average per cent returns. ....... 0. ce ec eee eee eee ena 23
It will be noted that in the B-maze the per cent of returns
from the shortened cul de sacs are practically equal to those
from the full length ones, both for the trained and for the un-
trained rats. The returns for untrained rats are not far short
of 50%. The shortage is mostly due, no doubt, to the small
degree of learning that took place in the process of the first
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 39
two trials, during which there was considerable random activity
and reduction of excess movements. It would seem that at
first—before any learning has taken place—the chance of a rat’s
returning on emergency from a blind alley is about one to one.
There may be a greater tendency to go forward, keeping the
general orientation rather than to return; if so, the excess for-
ward tendency is but slight. The returns from cul de sacs first
to be passed seem slightly to exceed in percentage those from
blind alleys further on toward the food box. In the B-mazes
the returns from cul de sac 1 (both full length and shortened)
are 44% of the total number of entrances; the corresponding
percentages for the other blind alleys in order from 2 to 10 are
55, 31, 32, 48, 33, 50, 34, 13, 33. These figures are taken, of
course, only from the records of the untrained rats, sixteen alto-
gether. Those most favorably situated for returns, so far as
the rat’s keeping the general direction on emergence from the
blind alley is concerned, are 2 and 5. This judgment is sup-
ported by the data. It is not clear why the returns from 7
should run so high. The percentage of returns by the eight
untrained rats in the A-mazes are, for the 2nd to the 6th blind
alley, in order: 36, 33, 67, 0, and 0. The large number for 4
was to be expected. The greater number of returns from the
cul de sacs first encountered is likely due to the fact that the
animals had already learned something of keeping the general
orientation before the other blind alleys were entered.
In the B-mazes there appears to be a slight decrease in the
returns of the first two trials by the trained rats as compared
with the untrained. This seems to be due to a sort of “ transfer
of training.” It is likely, as the writer suggested in the earlier
article already referred to, due to a tendency of animals with
experience in mazes to proceed with less whole-souled response
into cul de sacs. Let us suppose that as an animal enters a cul
de sac it also receives certain stimuli of various kinds from the
true path from which it departs. These stimuli may produce
a weak partial response, or tendency to response, which does
not immediately fade away. If this tendency persists until the
. tat emerges from the cul de sac it will, of course, enhance the
impulse to take the true path and thus increase the probability
of continued forward movement. It is not inconceivable that
a trained animal may have developed a habit of keeping the
40 JOSEPH PETERSON
correct general orientation by some such means as this. Such
habits would.then have common factors for all cul de sacs, and
in mazes of different kinds. It would seem, too, that on some
such basis as this the returns would be eliminated more readily
than entrances to the blind alleys, as has already been shown
to be the case. This explanation may involve an interaction
of sensory and motor impulses in the nerve fibres—each sys-
tem, sensory and motor, interacting upon and stimulating the
other—in such a manner as to make comprehensible how the
effect of stimuli may be carried over into later responses and
partly condition them as suggested below.
Possibly the animals also learn with training to utilize better
such factors as vague visual stimuli of the closed end of the
cul de sac. Certainly the speed of the rat running into the
blind alley would make one cautious in assuming that such
factors are explicitly reacted to by the animal. That there
was a real transfer of some kind is, in any event, a conclusion
which also finds support in the results of the A-mazes. For
the full length and the shortened cul de sacs, the per cent returns
for untrained rats are 42 and 32, respectively, agreeing rather
closely with the B-maze results, whereas the corresponding per-
centage returns by the trained rats—seven in each A-maze—
are 36 and 11, a decrease from that of the untrained animals
of 14% for the full length and of 66% for the shortened cul
de sacs. In the B-mazes the percentage returns from the full
length cul de sacs by trained rats is 24% less than that by un-
trained rats; for the shortened blind alleys the percentage re-
turns by the trained rats is 21% less than that by untrained
rats.
THE SIGNIFICANCE OF THE RESULTS
It may be urged by the reader that the more rapid elimination
of entrances to the shortened cul de sacs than to the full length
ones is due to the fact that the rat, in the case of the short blind
alleys at least, sees the closed end and thereby avoids entering
so frequently, or so completely. In one sense this begs the
whole question. Seeing is not some thing that stimulates or
directs the animal; it is only a mode of being stimulated. Its
possibility in the present study is not at all denied. The whole
question with which we are concerned is: How do all possible
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 41
kinds of stimuli operate, directly or indirectly, toward the learning
to avoid entering cul de sacs?
That the rat is not wholly blind has been demonstrated in
a number of cases,?° but there is no clear evidence to show that
the presence of such visual factors as are possible to the rat
could operate on the principle of frequency, recency, or intensity,
or all combined, in such a manner as to eliminate the impulses
to enter the cul de sacs under the conditions of the present prob-
lem. They might, of course, aid the rat in getting to the food
at any one time, but how could they operate toward cutting
short the random processes in successive trials, i.¢., in bringing
about what is called learning? A brief review of the work on
visual controls in the rat’s behavior is to be found in Miss Vin-
cent’s paper. Waugh found: that though the mouse could
perceive the distance of objects “ within a range of 15 cm.,”
it nevertheless seemed not to make use of the ‘‘ visual percep-
tion of depth”’ in getting past two partitions each from oppo-
site sides reaching half way across the problem box, the one
being nearer than the other.
In the present experiment, it will be recalled, the interior of
the maze was stained black, and even if it be granted that the
rat could see the ends of some of the shortest cul de sacs there
would be but little difference in the visual stimuli between the
“blind” and the open alleys, in as much as both were obstructed
alike in the further end and the side opening of the latter was
not directly visible. Differences in brightness would be irregular
and but slight, as the room was lighted from three sides—south,
west, and slightly from the north—and an electric light was
directly over the maze. It should be said that no difference
in behavior between the rat blind in the left eye—No. 20—and
the other rats was noticeable though the experimenter kept
watch for such difference. More careful visual controls are of
course desirable.
‘But the real question is how any stimulus, visual or otherwise,
must operate together with other stimuli so as to inhibit
unsuccessful acts and to cause to survive those acts which bring
20 See Richardson, Florence. A Study of the Sensory Control of the White
Rat. Psychol. Mon., Ser. No. 48, 1909. Vincent, Stella B. The White Rat and
the Maze Problem—I. The Introduction of a Visual Control. Jour. Animal
Behav., 19 15, 5, 1-24. re ;
2 Waugh, K. T. The Roéle of Vision in the Mental Life of the Mouse. Jour.
Comp. Neurol. and Psychol., 1910, 20, 549-599.
42 JOSEPH PETERSON
success, in this case those acts which bring the animal to the
food box. The results follow the series of stimuli and responses
which take the animal through the maze. How can the result
work backwards? The writer believes that in the foregoing
pages he has presented plausible reasons and data to show the
absolute inadequacy of frequency and recency laws as the direct-
ing factors in maze learning. Frequency fails to give any basis
not only for this kind of learning in general but particularly
for the specific kinds of results obtained in the experiments
considered. In a complex situation like this, frequency explains
only how within a certain probability the rat will finally reach
the food, but it fails to explain why subsequent trials should
be improvements on the first one. It is not clear how recency,
as ordinarily understood, can aid the learning. The principle
of intensity needs re-interpretation. When several stimuli act
on an animal bringing about a series of responses as in this
case, the final one of which is the successful one, it appears that
somehow, not well understood yet, the various effects of these
stimuli hold over into that of the final stimulus and that all
together simultaneously act to direct the energy of the animal
into the most consistent channels. In the large, these channels
offer the least resistance and afford the most complete response.
It is in this sense that the successful acts are more intense than
others, and thus their effect is greater toward shaping the neural
pathways for their repetition and for the gradual elimination
of the more inconsistent and tentative responses leading up to
them. On this assumption it becomes somewhat comprehensible
why the maze is learned to a large extent ‘‘as a whole,” so
that small errors may throw the animal out completely, or
at some other part of the maze, when the habit is nearly per-
fected. The specific results of the present experiment are also
intelligible. These various hold-over effects in the extero- and
the proprio-ceptive systems afford the basis of imagery in human
behavior, and supply the ‘‘ large situation ’’ to which one reacts
ideally. They may function, so far as we can know, wholly
unconsciously or with but vague consciousness in the case of
the rat. In the human being habits of responding to separate
groupings of these factors may be acquired, and such exciting
factors may be aroused indirectly by association. Nothing is
gainedtin psychological explanation by assuming ‘‘ ideas” to
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 43.
explain behavior, unless in such cases we understand how the
ideal dispositions themsélves are acquired. The use of the
term zdea in the higher forms of behavior is justified then only
on the basis of simplicity of statement. There is none but
questionable evidence thus far that ideational behavior is different.
in any way but degree from sensori-motor, or the well known
trial and error, behavior. “Ideas” can function only when
the somewhat detachable dispositions, of which they are the
imperfect, subjective aspects, have been built up by experience,
and such dispositions require a rather complex nervous mechan-
ism. It is needless to say that no evidence of ideational behavior
has been found in the white rat. While, as has been pointed
out in the foregoing, there are likely some hold-over effects of
stimuli in the case of the rat, these likely operate more or less
mechanically and en masse so that the animal enjoys little
independence of action and is subject rather completely to the
dominance of the group of stimuli present or immediately past.
That is to say, the animal can respond only to present situations
though with a considerable number of random variations, until
the most consistent responses to that situation have fixed them-
selves to the exclusion of all others, after many repetitions of
trials. Then the response becomes uniform and mechanical to
a high degree.
The more advanced behavior as we see it in the case of
man—ideational behavior—differs from the lower forms illus-
trated in the present study in that it is less fixed and less
dependent upon immediate situations. Stimulus-response organ-
izations, or tendencies, are more detachable in their separate
smaller functional components; and the latter have richer pos-
sibilities of combinations among themselves, on the one hand,
and on the other there is less dependence for their functioning
upon direct or immediate stimulation. Various indirect and
vicarious stimuli come to serve adequately. Thus various.
systems of stimulus-response mechanisms may become organized
into inconceivably complex relationships about certain symbolic
stimuli, such as written or spoken words, various kinds of gestures
and attitudes of the stimulating individuals, associated objects,
sounds, contacts, and so on. It then becomes practically impos-
sible to predict which of the various aspects of the situation
will succeed in calling out its particular response. We shall
44 JOSEPH PETERSON
not here enter into further consideration of this complex behavior,
except to point out that when the various stimulus-response
mechanisms have become sufficiently well associated with
certain muscular strains or neural excitations, the revival of the
latter by favorable stimuli will call out the acts themselves.
Thus a stimulus may have entirely ceased to play upon the
sense ofgans from without and long periods of time may have
elapsed, and yet, because of this acquired organization, the
recurrence of any significant aspect of the outer situation, even
such as a sound associated with it, may revive the crucial exci-
tation and thus call'out the act. Something of this kind—
stimulated, however, by the original situation minus the light
when the animal is allowed to respond—likely takes place in
the delayed reactions of animals, though this assumption leaves
entirely open the question as to whether or not the animals
have ideas, a rather infertile question for science, it must be
confessed. More elaborate systems of acquired associations
make possible the continual thinking of absent situations which
we know that we ourselves experience. In these more «dvanced
forms of behavior groups of response systems may come so to
interact upon one another by associations and by stimulation
from the inward bodily conditions that rehearsal of a problem
mentally may take place long after actual practice has ceased,
thus changing behavior materially between practices. It is
yet questionable whether there are any such cases in animal
behavior.
In the foregoing pages we have called into question the prin-
ciples of frequency, recency, and intensity of stimulation as
usually understood in relation to the fixing of associations, so
far as their value in explaining learning is concerned. They do
not seem to account for the change in successive trials called
learning. This seems to be true at any rate for maze learning;
probably it holds for all kinds of learning. All that these fac-
tors do is, likely, to make more and more easy any associations
and acts brought about by the real directing factors. That
is, they tend to fix any series of acts in the order that they are
gone through, not to change the order of the acts. Some other
directing factors and some vis a tergo must be found to account
_* Cf. Yerkes, R. M. The Mental Life of Monkeys and Apes: A Study of Idea-
tional Behavior. Behav. Mon., 1916, 3, No. 1. Yerkes thinks Julius, an orang-
utan, solved a problem ideationally; see particularly pp. 68 and 131.
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 45
for the changes in behavior which gradually make response
more and more direct and which gradually eliminates the use-
less random acts. We must not forget that the numerous
internal life processes, e.g., the contractions of the muscles of
the stomach with hunger, serve as the motivation to activity.
They determine the stimulating value, as do also modifications
in the proprio-ceptive system by past behavior, of various
outside factors. The organism continues to respond by vary-
ing behavior until successes are attained which modify these
internal conditions and change the inner motivating factors.
But the failures also change the organism. The directing fac-
tors of the response seem to be the inner organic processes
and the total combination of stimuli from external conditions
and from muscular contractions, all these overlapping in their
several effects as has been suggested. The neural channels
involved in the most consistent acts become the most opera-
tive through the compelling effects of all these factors, and
these acts, or directions of response, in time survive over all
others and ‘gradually acquire an ease and automaticity of func-
tioning characteristic of habits. The stimuli to action even in
as simple an organism as a rat are infinitely more complex than
usually imagined in our ‘‘ neural explanations.’”’ Mere contin-
gency in the combinations of acts of a rat brought about in
the maze, or in other problem boxes, for that matter, cannot
be regarded as the important factor that it has sometimes been
supposed to be. It is true that some useless acts may occa-
sionally survive with the more consistent ones by chance asso-
ciations, but such acts are really not vital parts of the system
of learned acts.
The precise nature of the hold-over effects of various stimuli
posited in the explanations of learning here suggested must be
left to physiology and neurology. There is undoubtedly a close
connection between sensory and motor impulses. Sensory stim-
uli bring about responses which in their different stages of expres-
sion set up new afferent impulses, or either facilitate or tend to
inhibit old ones; these again modify the motor tendencies. We.
are a long way yet from a satisfactory knowledge of nerve im-
pulses and their effects upon one another,—Are they periodic
or continuous? What relations obtain between stimulus changes
and nerve impulse changes? What is the nature of inhibition
46 JOSEPH PETERSON
and of facilitation? These and many other problems not yet
solved have important bearings upon our knowledge of the learn-
ing act. But psychologists cannot wait for the solution of these
problems before attempting to formulate more satisfactory con-
ceptions of the processes with which they must deal at every
turn. It must be apparent that chaos now reigns with respect
to this matter. Some writers invoke imitation to explain most
modifications in behavior; others use pleasure and pain for the
same purpose; while ideas, purposes, the effects of random acts,
and so on, are freely used directly or indirectly by most writers.
All of these factors may have real parts to play in the learning
process, in some one or more of its various aspects, but they
are all more or less vaguely conceived and frequently erroneously
referred to, almost as some sort of original or spontaneous causes,
rather than complex aspects of the very thing that is to be better
understood and analyzed. Popular, educational, and soz‘ologi-
cal writers may be forgiven for their own sins in this part cular
so long as psychologists have nothing more satisfactory to offer
than at present. The great problem of how learning takes
place is yet largely unsolved.
For the best progress, experiments in behavior modification
must go hand in hand with physiological investigations into the
nature of the nerve impulse. A few rather suggestive studies
have been carried out by psychologists upon the mutual effects
of successive acts on one another. It appears that while one
particular kind of act is being learned a second contrary one
is inhibited by it more than after the first has been completed.
The extensive investigations of Professor T. G. Brown,?4 on the
physiological side, have shown a summation of successive liminal
stimuli (facilitation) of intervals up to about ten seconds. Such
neural overlapping effects may well function to bring about a
* Pillsbury, discussing experiments on associative inhibition by Miiller and
Schumann (1894), concludes that ‘‘ where several things are to be learned in the
same connection, it is found that inhibition ceases to be effective if the first is
thoroughly learned before the second is begun.” Fundamentals of Psychology,
1916, p. 359. See also p. 365. Especially interesting in this regard is a study
recently reported by Hunter,—Hunter, W. S., and Yarbrough, Jos. U. The In-
- terference of Auditory Habits in the White Rat. Jour. Animal Behav., 1917, 7,
49-65. See especially pages 60 ff. One must be careful not to generalize too
much from these experiments on contrary acts.
* Brown, T. G. On the Phenomenon of Facilitation. I. Its Occurrence in
Reactions Induced by Stimulation of the “Motor” Cortex of the Cerebrum in
Monkeys. Quart. Jour. of Exper. Physiol., 1915, 9, 81-99. Other articles by the
same authority in the same journal.
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 47
simultaneous operation to some extent of the various experi-
ences that a rat has in finding the food box in the maze. In
many types of learning we have been much in the dark as to
how later effects of the successful results could work back and
stamp in these successful acts to the exclusion of the various
unsuccessful ones. By the conception of the overlapping of
effects of successive nerve functionings may we not be getting
a start in the right direction?
DISCUSSION
Peckstein?s has recently tried to explain the transfer effects
found in his experiments on the basis of factors which the writer
finds extremely vague, subjective, and otherwise technically
objectionable. The general factors of his explanation are:
(1) ‘General maze habits ’’—reduction of tendency to return,
knowledge of the nature of errors, improved sense of direction;
(2) “ consciousness of power;’’ and (3) ‘‘ proper emotional atti-
tude.” Specific factors are such as common specific identities,
or near-identities, in the different mazes. We are told that
return is due to the general ‘“‘ dominance of the familiar.” ‘‘ The
return pathway is known to be safe. The rats seem natively
inclined to return to the closed entrance.’”’ This return ten-
dency—due to knowledge or instinct?—is actually inhibited by
any maze for any other. The knowledge of the nature of errors
is a ‘‘ concept,” we are told, developed in the earlier sections of
the total maze. <A cul de sac “‘ ceases to be a detail that must
be cautiously explored,” and ‘comes to mean a detail that
must be left as soon as possible.’’ At first—now we are at the
“sense of direction’’ factor—some learners ‘“‘ have almost a
‘going ahead’ instinct,’’ while others have a greater tendency
to return. This latter tendency is gradually overcome. This
seems, then, only to be another name for the factor mentioned
under “returns.” ‘‘In subsequent mazes, the truly sophisti-
cated learner will enter the cul de sac, but will proceed along
the forward pathway when he returns to the true course.”’
The “‘ consciousness of power ’”’ in the rats seems to manifest
itself, after all, in some objective behavior change, such as
increased activity. ‘‘In subsequent mazes, however, the con-
sciousness of power is clearly seen (!). No ‘warming-up’ period
% Op. cil., pp. 50-54.
4
(a3
48 JOSEPH PETERSON
is needed. There is no delay at the entrance. Work has come
to mean invariable accomplishment and reward. The entire
attack upon the new problem is aggressive. The learner has
learned to do by doing.” The proper emotional attitude, the
last of the general factors, means the overcoming of an attitude
complex, ‘“‘a mixture of fear, indecision, curiosity, and perhaps
anger.’’ All this after some really valuable experiments! Surely
this is only a complication in subjective terms of facts to be
accounted for, which facts practically all authorities are willing
to accept more or less completely. These “ factors” of transfer
do not take us anywhere.
Dr. Peckstein finds?* that the difficultness of mazes is not
proportional to their lengths, nor to the number of their blind
alleys. But why should it be? As to the number of cul de
sacs, it is obvious that if at first a rat tends in its ‘‘ choices’ at
bifurcations to follow chance laws—and our present results
point that way—difficultness ought to increase on some other
principle. The probability of passing any single cul de sac
successfully is 3/4, as Watson has pointed out, i. e., if we mean
by “ successfully ”’ that the animal either goes on in the correct
path, or, if it enters the blind alley, that on emergence from it
it keeps the general forward direction. The chance of passing
two blind alleys is therefore 9/16 (= 3/4 x 3/4); that of passing
three cul de sacs, (3/4)8; and so on. On this basis the chance
of getting through one unit of Peckstein’s maze—3 blind alleys
—is (3/4)3, while that of getting through the entire maze without
a return is (3/4)". In the former case the probability of a
success without returns is therefore over thirteen times that
in the latter. Complications from returns at any cul de sac
will be brought about by additions of other forward movements
beyond the point to which return is made, but each of these
additional forward runs may again be assumed to follow, before
any training sets in, the same probability law at each cul de sac
- that is followed in the original run. Thus the above calculation
may stand roughly as approximately correct. Its results—a
difficultness of the whole maze of over thirteen times that of
the quarter maze—agrees more closely with Peckstein’s actual
results, as estimated by him, than do those based on the
assumption of a direct proportionate increase in difficultness
2 Tbid., pp. 59-57.
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 49
with distance through the maze and number of cul de sacs.
Peckstein found the whole maze over twenty times more difficult
than the average of the four quarter mazes, whereas such a
direct proportionate increase of difficultness as he assumed
should make it but four times more difficult. Of course, many
other factors in any such calculations must be taken into
consideration. With Peckstein’s rats the relative degrees of
difficultness of the four sections of the maze were found, in
order from the first to the fourth quarter, to be 15, 1, 3, 2, as
determined by his combined trials-time-error formula. This
does not look much like equality. The excess-distance run by
the rats is certainly a factor as well worth while as any to con-
sider. Why was it not included?
So far, then, Dr. Peckstein’s results, as presented by himself,
seem roughly to agree with our own in supporting the view
that mere probability laws account for the original ‘‘ choices ”’
of the untrained rat at the several bifurcations in the maze.
This is our own interpretation of his data, not his, it should be
stated. He merely seems to hold that there is some law of
diminishing returns, which he does not clearly state, that deter-
mines the degree of energy expended for the learning of mazes
of varying complexity.
Dr. G. V. Hamilton in his interesting study of perseverance
reactions, by the multiple choice method as he has developed
it, finds frequency and recency of an advantageous response
more strongly effective toward learning than either frequency
or recency with no advantage or with actual disadvantage.:’.
He finds that frequency with invariable advantage is stronger
in effect toward the building of a habit than even greater fre-
quency without an invariable advantage. But, as in most
experiments on learning, he has his conditions so arranged that
the animal can end up only with the “ successful” act. E. g.,
Hamilton says: ‘‘ During the twenty habit forming trials under
discussion she [Rat No. 1] manifested only three recency first
choices, but after these trials [that is, when the habit was learned]
during which the operation of the factor of recency was invariably
advantageous she manifested 100% of recency first choices.’
ar A Study of Perseverance Reactions in Primates and Rodents. Behav. Mon.,
Ser. No. 13, 1916.
28 Ibid., pp. 38-46.
29 Tbid., p. 40.
50 JOSEPH PETERSON
How could she do otherwise after learning is accomplished?
Here the success of the final act was inevitable by the con-
ditions of the experiment. The final high degree of success is
the result of the learning, how, then, can it get around to
come in at the front door as one of the causative factors?
SUMMARY AND CONCLUSIONS
The “principles of learning’ frequency, recency, and intensity,
in their usually accepted meaning, have been found inadequate
to account for learning in the maze. Probability laws alone
make possible a sufficient number of right choices for the rat
to reach the food box finally in the ordinary maze. The
probability of reaching the food box by mere chance rapidly
decreases with the increase in the number of cul de sacs in the
maze. But it is found that on laws of pure fortuity there is no
explanation for the elimination of cul de sacs; for since the
probability of entering any blind alley on returns as well as on
forward runs is 1/2, the habit of continuing to enter them should
be as strong as that of keeping the right trail toward the food
box. For learning to be possible, some sort of short-circuiting
process must take place by which the true path may be suggested
for the line of action when the animal gets to the entrance of
any blind alley. It is not clear how any of the usually accepted
laws of learning—frequency, recency, and intensity—can operate
to bring this about. Frequency and recency fail entirely to
account for the behavior of the rat in the maze. The real
process of learning, the gradual elimination of unsuccessful
random acts, such as entrances to cul de sacs and returns toward
the entrance place in the maze, must be accounted for on the
basis of some entirely different principle. The principles named
show only how an act, directed by some other factor, becomes
gradually more mechanically reflex.»
%0 Statistically the statement in this paragraph, as well as the one in the first
part of the monograph, is inaccurate. An animal coming the first time to a blind
alley has a probability of 1/2 of entering it; a probability of 3/4 of continuing in
the right direction, whether or not the blind alley is entered; and a probability of
1/4 of entering the CUL DE SAC and, from it, returning toward the starting place
in the maze. If the animal actually gets by the blind alley in question, enters one
farther on and returns in the maze, the conditions are reversed at the first blind
alley. Now the probability of continuing back to the starting place in the maze,
ie., either of not entering the blind alley at all or of entering and then continuing
in the return direction, is 3/4; that of getting reériented in the right direction toward
the food is 1/4; and that of entering the blind alley is 1/2. Adding these fractions
to those above for the respective directions in which the animal can possibly go
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 51
The present experiment was devised to present conditions
which might test the efficiency of the ‘‘ completeness of response ”’
theory outlined recently by the writer, suggesting a means of
learning based on the overlapping and thereby simultaneously
operative effects of successive stimuli. Identical mazes were
used for separate groups of animals, but they were so arranged
that their several cul de sacs could be conveniently varied in
length. By this means control groups of rats were run in mazes
differing only in the relative lengths of their cul de sacs, certain
of these being long for one group and short for the other. Two
modifications of such differences were used; the one pair of
control groups having all the blind alleys short in the one maze
and all long in the other, while the other pair of controls each
had some long and some short blind alleys making the total
length of blind alleys equal for both members of the pair. In
all, twenty-four rats were used. Groups of rats were interchanged
in the mazes, after the first problems were completed, so that
each problem was tried both by trained and by untrained animals.
Detailed records were kept of the behavior of the animals.
Complete entrances, half way entrances, and beginning entrances
to cul de sacs were indicated; complete returns and returns to
blind alleys already passed were noted; and the direction of the
rat’s movement on emerging from blind alleys, whether forward
or back, were recorded. The exact time for each trial was
kept but not used in the present report.
we have: forward from the blind alley 3/4 + 1/41; into the blind alley 1/2 +
1/21; and return toward the starting place in the maze 1/4 + 3/4—=1. This
gives equal exercise to the acts in all these three directions, on pure probability
laws, when returns are considered. But the animal is taken out of the maze only
at the food end of the trail; hence for each trial there must be one more forward
run at any given place in the maze than return runs. This gives the forward direc-
tion an advantage statistically of 1/4 runs for each trial over the entrance to the
cul de sac and of 1/2 over returns. This advantage is proportionately small where
many returns are made, as near the maze entrance, and large where this is not
the case, as near the food and later in the learning process at any given point. No
returns will be made to the last cul de sac, and when entrance to it has been elim-
nated none will be made to the one next to it; and so on. This condition, then,
affords a fine theoretical basis for explaining learning in the maze, and also for the
backward elimination of errors of entrance to blind alleys. There are, however,
serious flaws in this argument when given in support of frequency, either alone or
combined with recency, as the only principle operative in the learning of the maze.
Frequency and recency factors really operate against this explanation, rather than
in favor of it; for they favor the mere repetition of the choices first made at any
of these critical positions in the maze, and therefore the strengthening of the im-
pulses to enter blind alleys rather than their weakening. The force of this point
will be shown concretely in the paper now in preparation.
52 JOSEPH PETERSON
1. The decrease in the percentage of returns by the animal
emerging from blind alleys is very rapid in the early part of the
learning, and as a rule the rat continues to enter blind alleys,
even to their full length, long after returns are discontinued;
i. e., the curve of returns from blind alleys drops much more
rapidly than that representing the number of entrances to blind
alleys. These returns persist longer in the case of cul de sacs
encountered along the first part of the correct path than in that
of those nearer the food box.
2. The elimination of entrances to blind alleys does not come
about mainly by a decrease in the number of entrances, but
principally, especially in the case of the longer cul de sacs, by
a gradual decrease in the degree, or the distance, of entrance.
Just before entrance is eliminated completely, there frequently
occurs a peculiar and very rapid vibration of the rat’s head
between the direction of the true path and that of the tempting
blind alley. Frequently, after the first success in passing any
such blind alley, the rat runs headlong into some cul de sac
farther along the correct trail, which it had previously learned
to avoid. These and other facts of similar import indicate
that the maze is learned ‘“‘as a whole”’ to a large extent, and
that entrances to blind alleys are not properly to be regarded
as separate acts, as is frequently done in speculations on learning.
3. Entrances to short cul de sacs are eliminated more readily,
other things equal, than entrances to long ones. Not only are
the total entrances to the short blind alleys fewer than to the
longer ones, but the percentage elimination of them is greater.
The curve of decrease of entrances drops more rapidly in the
case of short than in that of long cul de sacs.
4. Blind alleys first to be passed along the true path are
entered more frequently than those further along—nearer the
food box—and their percentage rate of elimination is less. That
is, entrances to the first cul de sacs encountered are more persis-
tent, harder to overcome, than those to cul de sacs nearer the
food box.
5. With untrained rats the number of returns toward the
entrance door in the maze, on the rats’ emergence from blind
alleys, nearly, if not quite, equals in the beginning of the experi-
ment the number of cases of keeping the general forward direction
toward the food box. It appears that at the beginning stage
of learning in the maze mere probability determines whether
EFFECT OF LENGTH OF BLIND ALLEYS ON MAZE LEARNING 53
the animal goes forward or back on emerging from a blind
alley. In this respect, however, as in many others, there are
rather large individual differences. From the very first ex-
perience in the maze, and this makes the test of the probability
law rather difficult, the learning factors enter in and rapidly
decrease the returns in favor of the general forward orientation.
6. It has been found desirable in work of this kind to study
individual reactions in detail. Mere averages do not show the
significant aspects of the behavior in many cases. A detailed
report of individual ‘‘ choices’ in the maze, by a method which
promises to be fruitful, is being prepared to justify further the
statement in the present paper regarding the inadequacy of
frequency and recency laws as explanations of the rat’s maze-
learning.
7. Responses to stimuli cannot .take place instantaneously,
neither do stimulation effects fade away momentarily. Besides
this, response tendencies and muscular strains, maintained for
a shorter or longer time, constantly set up new sensory impulses
(proprio-ceptive stimuli) which again stimulate reactions. It
is suggested that by such means as these, and possibly by others
not yet known, the effects of successive stimuli, such as an
animal encounters in getting through a problem box to food,
operate in a measure simultaneously, and the resulting response
is on the whole the most consistent or complete one under the
whole circumstance. The channels to this most complete
response are gradually forced most open or permeable; their
greater consistency of operation (facilitation) brings about an
intensity of activity through them which in repeated trials
gradually short-circuits through the infinitely numerous path-
ways involved and thus brings about the gradual elimination
of useless random acts. It is suggested that learning comes
about by this means. It is hoped that this suggestion may be
fruitful toward an understanding of how a final success can
operate back (as it appears externally to do) upon the random
acts leading to it so as gradually to bring about their elimination.
This is the theory which the writer has called the ‘‘ completeness
of response ”’ principle in learning, and it seems to him to account
for the results obtained in the present experiment as well as for
others which have been uncritically attributed to the stamping-in
effects of pleasantness.
The Behavior Monographs
Edited by JOHN B. WATSON
The Johns Hopkins University, nian Md.
VOLUME i.
No. 1 The development of certain instincts and habits in chicks, By
Frederick S. Breed. Pp. iv + 78, $1.00, postpaid.
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