164 Animal Intelligence 



at different ages, because it seemed rather cruel and degrad- 

 ing to the experimenter. When in the case of the older chicks 

 nature happened to make the experiment, it was hard to de- 

 cide whether there was more violent fear of the jumping cat 

 than there was when one threw a basket or football into the 

 pen. There was not very much more. 



We may now proceed to a brief recital of the facts shown 

 by the experiments in so far as they are novel. It should be 

 remembered throughout that in every case chicks of differ- 

 ent ages were tested so as to demonstrate transitory in- 

 stincts if such existed, e.g., the presence of a fear of flame 

 was tested with chicks 59 and 60, one day old, 30 and 32, two 

 days old, 21 and 22, three days old, 23 and 24, seven days 

 old, 27 and 29, nine days old, 16 and 19, eleven days old, 

 and so on up to twenty-days-old chicks. By thus using 

 different subjects at each trial one, of course, eliminates any 

 influence of experience. 



The first notable fact is that there develops in the first 

 month a general fear of novel objects in motion. For four 

 or five days there seems to be no such. You may throw a 

 hat or slipper or shaving mug at a chick of that age, and he 

 will do no more than get out of the way of it. But a twenty- 

 five-days-old chick will generally chirr, run and crouch for 

 five or ten seconds. My records show this sort of thing be- 

 ginning about the tenth day, but it is about ten days more 

 before it is very marked. In general, also, the reaction is 

 more pronounced if many chicks are together, and is then 

 displayed earlier (only two at a time were taken in the ex- 

 periments the results of which have just been quoted). 

 Thus the reaction is to some degree a social performance, the 

 presence of other chicks combining with the strange object 

 to increase the vigor of the reaction. Chicks ordinarily 

 scatter apart when they thus run from an object. 



