220

PSYCHOLOGY IN HUMAN AFFAIRS

the cola drinks containing caffeine, tea containing both caffeine and
theophylline, and cocoa containing theobrominc are widely used today.
According to an early legend, shepherds observed that goats that
had eaten of the coffee berry did not rest but gamboled and frisked
about all night. A prior, who wished to stay awake to pray, instructed
the shepherds to bring him the berries so that he might make a brew for
his own use, and so came the discovery of coffee. From such old tales

TABLE 85.—RELATIVE POTENCIES OF CAFFEINE, TETEOPHYLLINE, AND

TlIEOBROMINKt

Drug
Central nervous system
Respiratory stimulation
Diuresis
Coro-nary stimulation
Cardiac stimulation
Skeletal muscle stimulation

Caff ei no ........
1*
1
3
3
3
2

Thcophylline . . Thoobromine. . .
2 3
2 3
1 2
1 2
1 2
3 1

* 1—most potent.
t From Goodman, L, and Oilman, A, The Pharmacological Basis of Therapeutics, p. 275, The
Macmillan Company, New York, 1944.
as this we can infer that the stimulating nature of the drugs has long
been known.
A cup of coffee contains about 1J^ grains of caffeine while tea con-
tains only slightly less, if any, of the active agent when brewed. There
is little doubt that these beverages are often consumed for their
stimulating effect even though most drinkers are unaware of the stimu-
lation. This property probably forms the basis of their popularity and
results in a true, though usually harmless, addiction. Here, as with
other drugs, the degree to which the individual is stimulated depends
upon personal tolerance. For most people, one cup of coffee has
negligible effects, but there are some rare cases in which results border-
ing on the toxic are caused by this amount including insomnia, restless-
ness, and excitement. In some persons 1 or more grams may produce
delirium. The fatal oral dose is estimated to be 10 g., although no
deaths have been reported from this cause.
Hollingworth's1 study of caffeine effects on psychological functions
has withstood the test of subsequent research, which uniformly shows
this drug to shorten reaction time. Although experiments have
reported it to exert rather conflicting effects on naeatal functioning,
1 Hollingworth, H. L., The Influence of Caffeine on Mental and Motor Effi-
ciency, Arch* PsychoL, N.Y., 1912, No, 22.