The Mental Life of the Monkeys 



201 



Fig. 29 gives facsimiles of the different signals reduced to 

 one sixth their actual size. The drawing of 101 is not accu- 

 rate, the outer ring being too thick. 



EXPERIMENTS WITH No. 2 



I first secured the partial formation of the habit of coming 

 down when I took a bit of food in my hand. I then used the 

 apparatus for exposing cards, YES in front being the 'yes' 

 signal and a circle at the back being the 'no ' signal. I gave 

 No. 225 trials with the ' yes ' signal and then began a regular 



Rigkt Kar.d A. Uft hand A 



near 



Palm upB 



Held 



op 



A. 



Low front 



FIG. 31. 



experiment similar to those described. After about 90 trials 

 (November 9-12, 1900) there was no progress toward differ- 

 entiation of response, and it was evident from No. 2's be- 

 havior that he was reacting solely to the movements of my 

 hand. So I abandoned the exposing apparatus and used 

 (November 11-13, JQ 00 ) as the 'yes' signal the act of taking 

 the food with my left hand from a pile on the front of the box 

 and for the ' no ' signal the act of taking food with my right 

 hand from a pile 4 inches behind that just mentioned. 



