28 Animal Intelligence 



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 history 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 outside, 

 and such general matters as fatigue, indisposition, etc. 

 Therefore the work done by one investigator may be re- 

 peated and verified or modified by another. No personal 

 factor is present save in the observation and interpretation. 

 Again, our method gives some very important results 

 which are quite uninfluenced by any personal factor in any 

 way. The curves showing 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 observer 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 



