COMPARATIVE EFFECT OF CAFFEINE PER SE AND A CAFFEINE BEVERAGE (COFFEE) UPON THE REAC- TION TIME IN NORMAL YOUNG ADULTS

that the effect of caffeine per se and of caffeine in the coffee bever-age is approximately equal and similar, with a resulting decrease in reaction time varying in different individuals from two to six per centum. Recently, in the November, 1934, issue of this journal, a de-tailed paper (2) by Horst, Robinson, Jenkins, and Bao, reported the influence of single doses of caffeine and of coffee on the pulse, blood pressure and upon certain motor functions in man. These authors concluded that the performance of a simple movement (target test) was usually improved one or two hours after caffeine or coffee consumption; but impaired in certain individuals after twenty-five hours. In 1929, I published a paper (3) and also a summary (4) of similar experiments in 1934, in which was stated the results of an experimental study to determine the effect of caffeine and of its equivalent amount in the form of the coffee beverage, upon the blood pressure of normal men and women of the college age. The above authors (2) have confirmed, in part, my data in that the resultant changes in blood pressure were found to be small. The variations in pulse rate (3) were slight and gave superim-posed curves, the significance of which seemed to be nil. Two years ago, an occasion arose to measure reaction time in human subjects and I compiled data regarding caffeine and coffee effects. After reading the above papers (1, 2) and checking with my un-published data, I found that certain differences were apparent