June 30, 1916] 



SCIENCE 



911 



for the eye to react, i. e., to look over to a 

 new stimulus to the right or to the left of 

 the position which the eye has been occupy- 

 ing. The subject was placed with his eye 

 near the lens of a long photographic 

 camera; a beam of soft blue light from an 

 arc lamp was then projected at will upon 

 the eyeball and reflected through the lens, 

 which focused it to a small point upon a 

 sensitive plate in the camera. The eye 

 looked at a fixation mark; this suddenly 

 disappeared, exposing in an unknown posi- 

 tion a single letter which was 1, 2 or 3 

 centimeters to the right or to the left of the 

 fixation mark. At the moment of exposure 

 the actinic light was allowed to fall upon 

 the eyeball. A tuning fork interrupted the 

 light so that the record consists of a line of 

 dots, each dot representing one hundredth 

 of a second. A bend in the line indicates 

 the moment of reaction, thus giving a photo- 

 graphic record of the latent time as well as 

 the direction of movement. 



A second complex neural arc was the 

 reaction time to reading isolated words. 

 With an exposure apparatus of unique ad- 

 vantages 4-letter words were exposed, and 

 the subject was instructed to pronounce 

 each word immediately as soon as he saw 

 it. By means of a voice key with electric 

 contact a record could be made on the 

 kymograph drum of the moment of expo- 

 sure of the word and the instant of re- 

 sponse, thus giving the data for determin- 

 ing the latency of response. 



In conjunction with Dr. F. L. Wells, of 

 the McLean Hospital, a series of standard 

 free association tests were given to the sub- 

 jects. The procedure is so well known as 

 to make a description unnecessary here. 



Considerable attention was paid to the 

 effect of alcohol on memorizing, this being 

 one of the higher mental processes. A 

 series of 4-letter words were exposed back- 

 wards by attaching to the kymograph drum 



a piece of paper on which these words were 

 printed. As the drum rotated the last 

 letter of the word appeared first in the 

 window which limited the subject's view, 

 and not until the last letter had in turn 

 appeared could the subject pronounce the 

 word correctly. The words were repeated 

 three times and the saving in time required 

 to repeat the words in order was taken as 

 an index of residual memory. Occasionally 

 subjects could memorize the entire twelve 

 words so as to have a perfect score, pro- 

 nouncing each word before it was exposed. 



The effect of alcohol on the sensory 

 threshold was studied by means of the 

 faradic stimulation method of Martin. 

 This requires a carefully calibrated 

 Kronecker inductorium; the technique has 

 been admirably described by Dr. Martin.* 

 Very feeble shocks were produced and the 

 subject, with two fingers dipped in salt 

 solution, was told to indicate when the 

 shock was felt. By moving the coil in and 

 out a threshold could be established. Varia- 

 tions in the position of the coil were the 

 basis of a series of calculations which Dr. 

 Martin has developed, giving the results in 

 the terms of certain units. Since our work 

 is entirely differential, however, it is un- 

 necessary to discuss the character of these 

 units. 



No series of observations on the psycho- 

 logical effects of alcohol would be complete 

 without studies of the effect of alcohol on 

 motor coordination. After a considerable 

 amount of preliminary experimentation we 

 decided upon two measurements, the first 

 on the velocity of eye-movements, i. e., in 

 moving the eye from side to side through 

 an arc of about 40°, the second on the 

 reciprocal innervation of the middle finger. 

 The importance of the eye as a member for 

 studying muscular coordination has been 



* Martin, ' ' The Measurement of Induction 

 Shocks," New York, N. Y., 1912. 



