136 PSYCHOLOGICAL EFFECTS OF ALCOHOL. 



a probable difference in the receptors, when wire or needle electrodes are 

 used instead of fluid electrodes. In the former case, the sensory effect 

 was sharply localized and the receptors were probably superficial. In 

 the latter case the effect was more diffuse and the receptors were 

 probably those for deep sensibility. For one of their subjects, who had 

 a slight abrasion of one finger, each shock produced a distinct throb of 

 pain when that finger was used. 



Our own experience corresponds with this report. A cut or scratch 

 always occasioned a sharply localized, superficial pricking sensation. 

 The ordinary deep sensibility quality seemed to resemble that of a 

 slight, involuntary muscle-twitch. The apparent location of this sen- 

 sation, as reported by our subjects, was not necessarily at the point of 

 application of the electrodes, but usually at some more or less remote 

 point, often just above or between the fingers. Changes in the apparent 

 position of the sensation occasioned some disturbance. It seems clear 

 that the sensation quality of threshold electrical stimulation differs from 

 that of more intense electrical stimulation. It was noticed that even 

 threshold stimulation seemed to produce a different sense quality at 

 different tunes. It seemed sharper and quicker at some times, duller 

 and slower at others. 



A further difficulty that we encountered is the variability in the 

 degree of assurance that the sensation is present, which was demanded 

 by different subjects, and by the same subjects at different times. It 

 was not infrequent for a subject to say, "I really felt it before I pressed 

 the signal key, but I was not sure." There are objective evidences of 

 this difference. Dr. Wells kindly served as subject for two days' 

 Martin-threshold experiments, one with alcohol and one without. His 

 introspective notes show that he was aware of his being more easily satis- 

 fied of the presence of the sensations on the alcohol day. This is proved 

 to be correct by his records. They show that whereas without alcohol, 

 that is, on the normal day, he never once reported a sensation when 

 there was no stimulus; on the alcohol days such errors were very 

 numerous. Especially in experiments on the effect of drugs, we believe 

 that such differences of critical reliability should be taken into account. 

 They may be really more important for an understanding of the drug 

 action than the apparent changes in the threshold level. Unfortu- 

 nately, our realization of the possible importance of this secondary 

 phenomenon came too late to enable us to collect systematic data. We 

 have occasional notes, however, to indicate that other subjects showed 

 a similar tendency, especially under the influence of the larger dose of 

 alcohol. This experience leads us to a good working hypothesis as to 

 the probable nature of the new factor that the results indicate must 

 have influenced the threshold under the larger dose of alcohol. It must 

 be remembered that the receptors of a finger immersed in a liquid are 

 never entirely unexcited. Temperature and pressure sensations are 

 present at first. Even after adaptation or fatigue makes them indis- 



