Reaction Time.
Through the courtesy and kind co-operation of Dr. Charles H. Judd, in charge of the Yale Psychological Laboratory, these students were subjected to the same careful tests during the five months of their experiment as were applied to the soldier detail. The results which are presented in the following report, kindly prepared by Dr. Judd, indicate quite clearly that there was no general nervous change in the reactors as a result of the low proteid diet. The data presented by Dr. Judd in this connection will be found in the accompanying tables, which, while indicating no noticeable improvement in the nervous condition of the men, make it quite plain that no deterioration whatever occurred as the result of the lowered proteid metabolism.
Report on Reaction.
Reaction tests with the group of University students were conducted in essentially the same way as were the reaction tests with the soldiers. Details in regard to the method and apparatus employed need not be repeated. They can be found on [pages 274 to 276].
Two new tests were added to the regular reaction determinations. One of these consisted in taking a record of the number of taps which could be executed in ten seconds. The reactor was seated before a table on which was fastened a telegraph key. He held the key between his thumb and first two fingers, and at a given signal began tapping as rapidly as possible until told to stop. Each time he tapped he closed an electric circuit. The current thus made was carried through a marker which indicated on a smoked paper each make and break at the key. A time line from a rod vibrating at the rate of once every twentieth of a second was traced on the smoked paper parallel with the marker record. By a comparison of the time line with the marker record, it was easy to determine the number of taps made in ten seconds. At first, the number of taps per second were counted, but the results showed such uniformity from second to second on a given day that only the net results for the whole ten seconds are given in the tables.
W. L. ANDERSON BELLIS
Photographs taken prior to the experiment.
The second test added to the reaction tests was undertaken to determine the steadiness of the subjects. Two brass rods 40 cm. long were held in a vertical position at a distance of 7 mm. from each other. The subject took in his right hand a brass rod 40 cm. long and 5 mm. in diameter and tried to pass the end of this rod up and down between the vertical rods without touching them. The subject’s relation to the vertical rods may be further defined by saying that he stood directly in front of them and reached out nearly at arm’s length. The vertical rods were at about the height of his chest. In order to get a record of the accuracy with which the subject moved the hand-rod up and down without touching the vertical rods, the vertical rods and the hand-rod were connected with the two poles of an electric circuit. Whenever they touched they closed the circuit, and a marker placed in the same circuit recorded the fact on a smoked paper record. The time was recorded in parallel with this record, so that any long continued contact could be measured. For the most part, contacts were only of very brief duration. In reporting the results of this test, every contact made while passing the rod once downward and once upward is counted as at least one. Continued contacts are recorded as two, three or more, according to the period of duration. Where there are such added counts because of continued contacts, a second quantity is given in the tables after the first. This second quantity, which is enclosed in parenthesis, indicates merely the number of contacts without reference to whether they are long or short.
No special comments are necessary to explain the tables. Tables 1-5 report in sigmas, or thousandths of a second, the average time of ten reactions on the date, and for the subject, indicated. In the third column, is the mean variation for the series of ten reactions.