820 



SCIENCE. 



[N. S. Vol. VII. No. 181. 



tion, one gets a quantitative estimate of 

 what animals can learn and how they learn 

 it. 



What happens in all these cases is this : 

 The animal on being put into the box, and 

 so confronted with the situation ' confine- 

 ment with food outside,' bursts forth into 

 the instinctive activities which have in the 

 course of nature been connected with such 

 a situation. It tries to squeeze through any 

 openings, claws and bites at the walls con- 

 fining it, puts its paws through and claws 

 at things outside trying to pull itself out. 

 It may rush around, doing all this with 

 extraordinary vehemence and persistence. 

 If these impulsive activities fail to include 

 any movement which succeeds in opening 

 the door, the animal finally stops them and 

 remains quietly in the box. If in their 

 course the animal does accidentally work 

 the mechanism (claw the button round, for 

 instance), and thus win freedom and food, 

 the resulting pleasure will stamp in the act, 

 and when again put in the box the animal 

 will be likely to do it sooner. This con- 

 tinues ; all the squeezings and bitings and 

 clawings which do not hit the vital point 

 of the mechanism, and so do not result in 

 any pleasure, get stamped out, while the 

 particular impulse, which made the sucess- 

 ful clawing or biting, gets stamped in, until 

 finally it alone is connected with the sense- 

 impression of the box's interior, and it is 

 done at once when the animal is shut in. 

 The starting point for the formation of any 

 association is the fund of instinctive re- 

 actions. Whether or not in any case the 

 necessary act will be learned depends on 

 the possibility that in the course of these 

 reactions the animal will accidentally per- 

 form it. The progress from accidental per- 

 formance to regular, immediate, habitual 

 performance depends on the inhibiting 

 power of effort without pleasure and the 

 strengthening by pleasure of any impulse 

 that leads to it. 



Although it was of the utmost importance 

 to them to get out of the various boxes and 

 was, therefore, certain that they would use 

 to the full all their mental powers, none- 

 of the animals gave any sign of the posses- 

 sion of powers of inference, comparison or 

 generalization. Moreover, certain of the 

 experiments seem to take the ground from 

 beneath the feet of those who credit reason 

 to animals. For it was found that acts 

 (e. g., opening doors by depressing thumb- 

 latches and turning buttons) which these 

 theorizers have declared incapable of per- 

 formance by mere accident certainly can he 

 so done. It is, therefore, unnecessary to in- 

 voke reasoning to account for these and 

 similar successes with mechanical con- 

 trivances, and the argument based on them: 

 falls to the ground. Moreover, besides de- 

 stroying the value of the evidence which 

 has been offered for the presence of reason 

 in animals, the time-records give us posi- 

 tive evidence that the subjects of these 

 experiments could not reason. For the 

 slopes of the curves are gradual. Surely if a 

 cat made the movement from an inference- 

 that it would open the door, it ought, when 

 again put in, to make the movement im- 

 mediately. If its first success was due to an 

 inference, all trials after the first should 

 take a minimum time. And if there were 

 any slightest rudiment of a reasoning fac- 

 ultj', even if no real power of inference, the 

 cat ought at least sometime, in the course 

 of ten or twenty successful trials, to realize 

 that turning that button means getting out, 

 and thenceforth make the movement from 

 a decision, not a mei'e impulse. There 

 ought, that is, to be a sudden change from 

 the long, irregular times of impulsive ac- 

 tivity to a regular minimum time. The 

 change is as a fact very gradual. 



Finally, experiments made in another 

 connection show that these animals could 

 not learn to perform even the simplest acts 

 by seeing another do them or by being put 



