INDIVIDUALITY, TEMPERAMENT, AND GENIUS IN ANIMALS 239 



certainly would interest the general 

 reader much more than our printed 

 contribution toward the solution of our 

 problem.^ We therefore venture to pre- 

 sent certain of the fascinating by- 

 products of our summer's work. That 

 the differences which we are about to 

 emphasize are not necessarily individ- 

 ual, we readily admit; that they are 

 not age or species differences, we are 

 certain. We suspect that some, at least, 

 are sex differences. 



Xip and Tuck, for thus we early de- 

 cided to designate our subjects, soon 

 made us feci their individuality. Both, 

 under the spur of the hunger motive, 

 worked remarkably w^ell toward the so- 

 lution of ideational problems, and their 

 success in this work fully justified the 

 popular impression that the pig is one 

 of the more intelligent among mam- 

 mals. Xip, the male, v\'as less active 

 and energetic than his sister. Tuck. He 

 also was less greedy, and showed rather 

 less initiative and a more limited range 

 of reactions. Tuck it was who usually 

 led if there was opportunity for com- 

 petition, while Xip followed. Both 

 quickly became accustomed to the ex- 

 periment, but Xip showed more per- 

 sistent wariness, timidity, and suspi- 

 cion than did Tuck. She, however, 

 was much quicker in response, more 

 alert, curious, and quick to discover 

 new opportunities for pig satisfaction. 

 When at work on experimental prob- 

 lems, Xip was much more easily dis- 

 couraged and tended earlier than Tuck 

 to give up his search for the reward of 

 success. Tuck constantly acquired new 

 and profitable tricks, which as a rule 

 sooner or later appeared in Xip also, 

 sometimes spontaneously and again l)y 

 reason of the imitative tendency. 



^ Yerkes. Robert II., and Coburn, Charles A. 

 A Study of the Behavior of the Pig. Sits gcrofa, 

 by the Multiple-Choice Method. Journal of Ani- 

 mal Behavior, 1915: 5: 18.5-225. 



As day after day we observed these 

 two specimens of a mammalian type 

 whose life under domestication gives its 

 intelligence slight opportunity for dis- 

 play, we were strongly impressed, as we 

 liad been in the case of rats also, by the 

 importance of temperamental reactive 

 tendencies in responses to any experi- 

 mentally arranged situation. The ex- 

 perimenter who ignores individuality 

 or temperament in his subjects runs a 

 grave risk of misunderstanding or 

 wrongly evaluating his results. Our de- 

 scriptions sound anthropomorphic, but 

 that, the alert reader will appreciate, is 

 due to our avoidance of stilted and un- 

 natural terminology. We are attempt- 

 ing to describe in an intelligible way, 

 and briefly, behavior which, if we 

 should restrict ourselves to wholly ob- 

 jective terms, would require pages of 

 unusual behavioristic statement. 



Among the birds, there is probably 

 no more interesting object of study 

 than the crow. Its species characteris- 

 tics are notably alluring to the psychol- 

 ogist, but to us, as a result of- varied 

 observations in the corn fields of Penn- 

 sylvania and on the wooded hills of 

 Xew Hampshire, sex, age, and individ- 

 ual differences are no less fascinating. 

 One summer we removed a brood of 

 four young crows from their nest just 

 before they were able to fly. We could 

 not identify the sexes at the time, so 

 the differences we observed may be 

 either sex or individual, but at any 

 rate, the four specimens were as sharply 

 contrasted in temperament as are the 

 children of any household. 



We set al)out rearing these birds by 

 hand, the while taming them for ex- 

 perimental purposes. Within a few 

 days, one of the four began to exhibit 

 the characteristic fear reaction of its 

 species, and at once it became extremely 

 flifficult to feed. For a few davs we 



