14 HARRY H. WYLIE 



any one animal was to place it in the food box (F), allow 

 it to secure a morsel of food, open the door (ED) into the alley 

 (EA), then press the key K or K', as the case demanded, and 

 thus require the animal to choose the lighted or the noisy 

 return alley. In case the animal entered partly or wholly 

 into the unlighted or the quiet return alley it was accounted 

 an error. The door from the unlighted or the quiet return 

 alley to the food box was kept closed. The light stimulus 

 was not always given as a continuous stimulus in any one 

 trial until the choice of correct return alley had been made. 

 The stimulus was given sometimes continuously and some- 

 times brokenly. Care was taken that the action of the key 

 (K or K') was noiseless. In case of the sound stimulus it 

 was at first attempted to sound the clicks regularly until the 

 correct choice had been made. This plan, however, was not 

 followed in all the work reported. Whenever a different 

 course was followed it will be indicated. The following 

 order of choices between right and left return alleys was 

 required in each series of 20 trials: L, R, L, R, L, L, R, R, 

 L, R, L, R, L, L, R, R, L, L, R, R. 



D. Negative 



(1) Apparatus, — The apparatus for the negative response 

 consisted of a box approximately two feet by three, MNOP 

 in figure II. F represents the food box approximately 12 

 inches by 14 inches. This food box had three openings 

 or doors, ED being the entrance door from food box into 

 main alley, MA; RD and R'D' being return doors from return 

 alleys, RA and R'A', to food box. All the alleys had a uni- 

 form width of approximately five inches and a uniform depth 

 of six inches. From the main alley, MA, two winding alleys 

 led back to the food box. These are marked RA and R'A' 

 in the figure and are spoken of as return alleys. PP are 

 partial partitions obstructing the view of the return doors 

 and causing the animal to take a devious course back to the 

 food box. C, C, C, etc., are brass plates practically covering 

 the entire width of the bottom of the alleys and are joined to 

 batteries and an induction coil, IC in figure. S, S, S, etc., 

 are small electric sounders of the same type as used in the 

 positive experiments. They are here hung just inside the 



