Modification by Experience 279 



say the alphabet or the multiplication table, the learning 

 process has not involved the dropping out of any of the 

 movements. It would profit us little to pass inmiediately 

 from A to Z, dropping out the intervening movements, or to 

 skip at once from the first to the last stanza of a poem. We 

 find in such cases that repeated performance of the series 

 of movements results in two changes. First, the move\ 

 ments follow each other more rapidly : this can be ex-J 

 plained by the law of repetition, according to which the 

 oftener the nervous process traverses a certain pathway, 

 the less resistance it encounters. Secondly, the movementsA 

 of the series no longer need outside stimuli, but apparently 1 

 each movement supplies the stimulus for the next. When" 

 one is playing a piece of music for the first or second time, 

 each movement has to have the stimulus of the notes on 

 the page; when a piece has been long practised, each 

 movement sets up the next one 'automatically.' This 

 really means that as one movement is performed, the sen- 

 sory processes occasioned by the contraction of the muscles 

 involved excite the motor pathway for the next movement. 

 The stimulus for one movement is the kinsesthetic excita-l 

 tions received from the preceding movement. The truth 

 of this is evidenced by the fact that if we break down in 

 playing a certain passage, we can recover ourselves by 

 going back a little, so as to get the proper kinaesthetic 

 stimuli. 



This t}T)e of learning obviously functions in learning a j 

 maze path. Here we have to deal not with the acquiring / 

 of a single 'successful' movement and the dropping off of I 

 all others, but with the establishment of a whole series of/ 

 successful movements which must be performed in a cei-j 

 tain order. Much experimentation has been performed to 

 study the sensory cues involved in maze running. The 



