Eye Reaction. 59 



EYE REACTION TO PERIPHERALLY APPEARING STIMULI. 



Of the total 155 individual eye reactions which constitute this series, 

 only 12 were for any reason irregular and had to be omitted from the 

 averages. These reaction records were lost, not through technical 

 difficulties but because the subject voluntarily winked at the moment 

 of the exposure of the stimulus mark, or was inattentive to the task. 

 This is proved by the fact that his photographic records show that he 

 was not looking at the prefixation mark at the moment of stimulation. 

 Four of these irregular reactions occurred within 2 hours after alcohol 

 on July 4. The recording light was interrupted 100 times per second. 

 The individual reactions were read to the nearest half-hundredth of a 

 second. The data obtained in the measurements of the eye reaction 

 are given in table 9, according to the general form used in preceding 

 tables. 



The mean variations range from 4 per cent (R. T., 229, M. V., 9) to 

 19 per cent (R. T., 204, M. V., 39), with an average value which equals 

 about 14 per cent of the average reaction time. The reaction time 

 averages from day to day show relatively small variations, the normal 

 averages shown in the next to the last column being 192, 219, and 213 <r. 

 The same may be said for the first-period values for these normal days, 

 that is, 212, 204, and 217 a. The second alcohol day, July 2, shows a 

 first-period value of 237 a, which is unusually long for this series of 

 reactions. It is noteworthy that this particularly long normal occur- 

 ring on an alcohol day exercises a diminishing effect on the apparent 

 influence of alcohol on the reaction time. Consistency is further shown 

 by the fact that the general average for the first period for the three 

 normal days is 211 a, while that for the three alcohol days is 208 a. 

 Both these figures compare favorably with the general average of 208 <r 

 for the three normal days, from which the first-period values are ex- 

 cluded. The respective mean variations for these three compared 

 values are 33 and 30 <r for the normal and alcohol first periods and 29 o- 

 or the general average for the normal days. 



There is no conspicuous practice effect shown in these data. While 

 undoubtedly practice may result in a shorter eye-reaction time for a 

 subject with no experience in this measurement, 1 Subject VI had pos- 

 sibly had enough experience so that later experiments would not be 



following very quickly on the first reflex, so as to make it appear that the reflex involved a double 

 movement. The first stimulus was the signal to start a series of winks lasting for about 1 second. 

 As the interval between stimuli usually employed by Dodge and Benedict in this series was from 

 0.7 to 0.8 second, some of these voluntary winks were sure to precede the second reflex. The 

 voluntary lid movements are nearly all of what may be judged extreme amplitude. There is no 

 apparent change produced by alcohol in the frequency of the voluntary winking, nor does it seem 

 to decrease at all as the result of practice in the experiment. From 15 records in which voluntary 

 winking preceded the primary reflex the average latency and amplitude are 35.5 <r and 16.3 mm. 

 as compared with averages of 36.3 a and 16.0 mm. from 20 other normal records in which thi3 

 complication did not exist. 



1 See Dodge and Benedict's report, p. 89 et seq. Unpublished data on eye-reaction measure- 

 ments taken in 1916 and 1917 unmistakably bear out this finding of practice effect in eye reactions. 



