ANIMAL INTELLIGENCE. 7 



ment involved any important question of fact or theory, unless 

 I was sure that his motive was of the standard strength. With 

 chicks this is not practicable, on account of their delicacy. But 

 with them dislike of loneliness acts as a uniform motive to get 

 back to the other chicks. Cats (or rather kittens) , dogs and chicks 

 were the subjects of the experiments. All were apparently in 

 excellent health, save an occasional chick. 



By this method of experimentation the animals are put in 

 situations which call into activity their mental functions and 

 permit them to be carefully observed. One may, by following 

 it, observe personally more intelligent acts than are included in 

 any anecdotal collection. And this actual vision of animals in 

 the act of using their minds is far more fruitful than any amount 

 of histories of what animals have done without the history of 

 how they did it. But besides affording this opportunity for 

 purposeful and systematic observation, our method is valuable 

 because it frees the animal from any influence of the observer. 

 The animal's behavior is quite independent of any factors save 

 its own hunger, the mechanism of the box it is in, the food out- 

 side, and such general matters as fatigue, indisposition, etc. 

 Therefore the work done by one investigator may be repeated 

 and verified or modified by another. No personal factor is pres- 

 ent save in the observation and interpretation. Again, our 

 method gives some very important results which are quite unin- 

 fluenced by any personal factor in any way. The curves show- 

 ing the progress of the formation of associations, which are 

 obtained from the records of the times taken by the animal in 

 successive trials, are facts which may be obtained by any ob- 

 server who can tell time. They are absolute, and whatever can 

 be deduced from them is sure. So also the question of whether 

 an animal does or does not form a certain association requires 

 for an answer no higher qualification in the observer than a pair 

 of eyes. The literature of animal psychology shows so uni- 

 formly and often so sadly the influence of the personal equation 

 that any method which can partially eliminate it deserves a trial. 



Furthermore, although the associations formed are such as 

 could not have been previously experienced or provided for by 

 heredity, they are still not too remote from the animal's ordinary 



