The time of administration and some effects of 2 grs. of alkaloid caffeine.

Abstract

In 49 subjects it was found that 2 grains of caffeine retarded with increasing effect the development of an unfavorable attitude to the task of adding pairs of numbers for 2 hrs., as indicated by the rate of adding and subject ratings. Since the caffeine was administered \ hr. before the task was begun, was the increasing effectiveness due to the greater quantity of caffeine absorbed with time or to other factors? To answer this question, 29 subjects added for 8 successive 15-min. periods on each 4 occasions; 1 hr., 2 hrs., and 3 hrs. after the oral adm. of 2 grains of caffeine, and after a placebo. Suitable control techniques were employed. No initial effects on the rate of adding were observed regardless of the time of adm. but terminal subjective and adding rate effects were obtained. The effect of caffeine on a psychological performance, such as adding, is not due to an alleged stimulating effect on the neural processes immediately involved in the task, but rather to 2 factors: the anti-hypnotic quality of caffeine; and the opportunity provided by the exptl. framework for the development of hypnotic influences (boredom).