278 The Animal Mind 



ments where, after rats had learned a maze, the path was 

 altered, certain passages being closed and others opened. 

 The rats found it decidedly harder to learn to enter former 

 cul-de-sacs than to take those turnings which they had 

 formerly omitted merely because they were a longer way 

 around than the true path. The positively unpleasant 

 experience of running into a cul-de-sac had more com- 

 pletely eliminated the movements that led to it than did 

 the merely useless running of a longer passage. Finally, 



(it is clear that we cannot draw a hard and fast line between 

 a useless reaction and a harmful one. We have seen that 

 I severe punishment like an electric shock may delay learn- 

 (ng because it attaches itself to the learning situation as 

 I whole. And in the writer's experiments with rabbits 

 [756), a young rabbit of very nervous temperament was 

 rendered unfit for further experimentation simply by hap- 

 pening to push repeatedly at the wrong or closed door of 

 a box. He had been working well up to that time, but from 

 that time on he ran away whenever he was confronted with 

 ^the experiment box. It would appear that emotional 

 I factors in the animal may render movements positively 

 'yiarmful which would ordinarily be merely useless. 



§ 75. The Formation of Systems of Successive Movements 



We have now to consider another type of learning, dia- 

 metrically opposed to that of the dropping off of movements. 

 I In this type, the movements which an animal makes suc- 

 Vpessively become organized into a series. No movement of 

 [the series is dropped out as a result of the learning, but the 

 loftener the series is run through, the more rapidly it is 

 (performed. It is evident, if we consider our own learning 

 NprocesseS; tihat many of them are of this type. When we 



