The literary digest . era. A few minutes later a touch of the doctors finger upon theehutter-releases allows a flash of the electric light in the box behind the lens to reach your eye. At the same moment—soit seems to you—you press your finger upon the air-pressure in the drum simultaneously causes a needle tomark a line, more or less curved, on the lampblack-coveredpaper. Then the paper is taken off the cylinder. Here is the markof the doctors signal and there is the record of your doctor counts the number of waves of the vibrating needleon the paper, and informs you
The literary digest . era. A few minutes later a touch of the doctors finger upon theehutter-releases allows a flash of the electric light in the box behind the lens to reach your eye. At the same moment—soit seems to you—you press your finger upon the air-pressure in the drum simultaneously causes a needle tomark a line, more or less curved, on the lampblack-coveredpaper. Then the paper is taken off the cylinder. Here is the markof the doctors signal and there is the record of your doctor counts the number of waves of the vibrating needleon the paper, and informs you that 20/100 of a second claspedbetween the signal and your response. And you imagined yourpressure to have been simultaneous with the signal! You are assured that your brain functions normally—thatthe time for simple visual reactions in normal subjects averagesbetween and second. In the tests for reactions involving deliberation, the samedevice is used. You place one finger of the left hand on one of. Courtesy of Popular Science Monthly. TESTING HIS BRAIfJ-SPEED BY REACTION TO TOUCH. the little drums, one finger of the right hand on the other are informed that the left drum means blue, the rightdrum red. The doctor flashes a red or a blue light through the lens ofthe cameralike device, and you signal back the impression bypressing the right or the left drumhead. On examining therecord on the cylinder, you find that it took you more than twiceas long to react in this visual test as in the simple \isual test inwhich you were not called upon to decide whether the light wasred or blue. From hundreds of observations like these Professor Amarhas drawn interesting and valuable conclusions which enabledhim to determine the aptitude of the individual tested for cer-tain vocations, a problem of importance in finding emplojmentfor the thousands of soldiers returning from the war. The statistical material so far collected shows that the ageof the subject, between
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