32 HARRY H. WYLIE 



keys were not in the range of the animal's vision and the 

 finger movement or forearm movement necessary to work 

 them was also below the line where vision might function. 

 This result was secured mainly by having the alleys six 

 inches deep, making it practically impossible for the animals 

 to see any extraneous object or movement except where it 

 appeared immediately over the alley. The rest of the ex- 

 perimenter's body was practically immobile during the time 

 in which the reaction was to be made. As to the mechanical 

 jarring of the apparatus, the extremely light touch necessary 

 to work the keys would certainly render the jarring negli- 

 gible. In the writer's opinion the most likely to manifest 

 itself of the three possible types of things mentioned above 

 is the third. When an animal is required to turn back fif- 

 teen times out of every twenty, it is extremely probable that 

 it will acquire a habit of turning back, even when no stimu- 

 lus has been given. As has been stated the series of trials 

 used was particularly arranged to meet such a contingency. 

 The possibility of "order in the series" functioning was 

 eliminated by introducing irregularly the trials when the 

 stimulus was omitted. The possibility of "position in the 

 ■alley" functioning was eliminated by constantly varying the 

 point at which the sound or light stimulus was given. 

 Finally in cases where the animal did turn back and 

 entered the other return alley when no stimulus was given by 

 the experimenter or before such stimulus had been given, 

 the stimulus was given in the other alley and the animal 

 required to return to the alley first chosen to get back to 

 the food box. Since such cases were confined practically 

 to the work with the sound stimulus we shall omit the 

 discussion of them here. These cases were so rare when 

 using the light that they can well be neglected in considering 

 the results. 



The outstanding feature of the learning process here is 

 the shape or form of the learning curve. To bring out 

 the peculiar features more plainly, a number of curves are 

 presented. These curves show the record not only for 

 learning the light but also for the transfer to sound and 

 pain. See Figures V to XIII inclusive. 



It will be noticed that these curves show a period at first. 



