THE ASSOCIATION OF IDEAS 47 



would begin to waltz whenever he happened to take a step back- 

 ward with the left foot. Obviously, other stimulations are 

 needed to put the total nervous system into the condition of 

 integration in which the waltz series will be repeated, rather 

 than one of many other series. These stimulations are normally 

 furnished by the music, 10 the contact with a partner, and other 

 environmental features of the ball-room. Thought-processes, 

 including intentions, which are also essentially reactions depend- 

 ing on neural transits are important in selecting the habit to be 

 actualized; and in the absence of any of the customary environ- 

 mental influences the thought-processes alone may start the waltz 

 series: otherwise, the pupil would be unable to practice the steps 

 by himself. 



It is not to be supposed that the problems of habit formation 

 are solved by the muscle series hypothesis, or that this hypothesis 

 is put forward as more than a step in the total solution. Yet it 

 is an important step, and once taken, the way is cleared for con- 

 centration on the problems of selection and control of reaction 

 series. 



Let us consider now the details of the formation of a thought- 

 habit, basing our analysis on the memorizing of the following list 

 of words: coffee, quantity, brittle, aggravate, paper, sunny. Sup- 

 pose these words to be presented for learning, either by sounds 

 addressed to the auditory receptors, or by printed letter-combi- 

 nations addressed to the visual receptors. The perception of 

 each of these words depends on a complicated reaction which we 

 will suppose to have already been learned by the person who is to 



10 Unfortunately, to an increasingly large number of would-be dancers, the 

 music is no clue. The word "waltz" either displayed on a program or sign, or ob- 

 tained verbally from some other person, is the necessary stimulus; and the danc- 

 ing proceeds in a personal time-series, having no relation to the rhythm of the 

 music. In a modern ball room, the observer will notice that the number of steps 

 per minute of a large percentage of the dancers is not determined by the rate of 

 the musical rhythm; and may confirm his visual observation by the auditory 

 rhythm of the feet, and the lack of vibration of the floor which always marks uni- 

 son dancing. This sort of ' 'dancing" is a much simpler illustration of the serial 

 habit formation explained above than is real dancing, in which afferent auditory 

 current is continually participating in the series, no matter how completely it 

 may have been learned. 



