62 BIOLOGICAL LECTURES. 



ing grounds, to eat certain sorts of animals or plants, to run 

 away from certain enemies, to sleep in certain lairs. A kitten 

 when confined in a cage reacts instinctively with squeezings, 

 clawings, bitings, etc., some one of which may happen to open 

 a thumb-latch on the door and give it freedom. The pleasure 

 consequent may so stamp in that particular act, in connection 

 with that situation, that after enough experiences the animal 

 will, when put in that situation, manifest nothing of all the 

 instinctive activities first observed save the one particular poke 

 at the thumb-piece. Its activity now would seem far enough 

 from instinct to many people, but it is really a consequence of 

 instinctive activity. It has come to neglect the unsuccessful 

 squeezings and bitings, to choose the successful clawing, in 

 just the same way that the chick comes to neglect the peck- 

 in^s at excrement and match ends, and choose the food. 



I have already implied that instinctive activities may be 

 inhibited just as truly as they may be confirmed and reinforced. 

 If the conditions in which an animal lives become such that 

 an instinctive act brings discomfort, that activity tends to dis- 

 appear ; or if the animal has, prior to the appearance of a 

 certain instinct, learned to meet otherwise a situation which 

 would normally call forth the instinct, he may continue to 

 meet it in that rather than the instinctive way. It would even 

 be fairly reasonable to interpret the transitory instincts as 

 instincts which were inhibited by mere lack of exercise. A 

 convenient account of the inhibition of instincts may be found 

 in James's Psychology, Vol. II, pp. 394-397- I may quote in 

 addition examples of inhibition (i) by virtue of the previous 

 formation of a habit, (2) by (i) plus actual abolition through 

 resulting discomfort. 



An instance of the former sort is found in the history of a cat 

 which learns to pull a loop and so escape from a box whose top is 

 covered by a board nailed over it. If, after enough trials, you remove 

 a piece of the board covering the box, the cat, when put in, will still 

 pull the loop instead of crawling out through the opening thus made. 

 But, at any time, if she happens to notice the hole, she may make 

 use of it. An instance of the second sort is that of a chick which 

 has been put on a box with a wire screen at its edge, preventing it 



