6o POPULAR SCIENCE MONTHLY, 



the motor side the child's judgments are enormously increased 

 and are made more accurate. This is necessarily true because 

 by the use of the motor side his opportunities for comparison and 

 discrimination are multiplied. He is called upon, for instance, to 

 form a judgment out of the ideas already in his possession. If 

 now he stops with this judgment he has no new criteria with 

 which to judge its correctness. On the other hand, if he can con- 

 vert this judgment into motor terms a comparison is forthwith 

 instituted and the judgment undergoes revision. 



I have already spoken of the physical activity of youth as a 

 marked characteristic, and have said that this activity is due to 

 the discharge of energy into motor channels. It is a significant 

 fact that the attention of the child can be held for a surprisingly 

 long time provided he is so employed that this motor energy is ex- 

 pended in movement. Attention from the first is therefore close- 

 ly related to the motor side. The reason seems to be that there 

 are many groups of cells more or less isolated from each other, 

 but each closely connected with the main branches of the nervous 

 system. Each group has functions largely peculiar to itself; 

 when the brain is fully developed these isolated groups of cells 

 become more closely interrelated by means of filamentary out- 

 growths, called by some writers pathways of association and by 

 others dynamic pathways, by which energy is more readily dis- 

 tributed to various groups. In other words, if I may use a bold 

 metaphor, short circuits become at last established between the 

 various centers, so that the energy is not discharged into the 

 early isolated channels. If, therefore, we wish to hold the child's 

 attention to any particular line of study, we must at the same 

 time provide for the expenditure of the energy that is gathered 

 in the other groups of cells whose connections of interrelation 

 are not yet built up or established. If we do not provide for this, 

 the natural discharge of the energy from the overfilled cells of 

 those other groups swerves the child's attention from what we 

 have in hand for him. Every mental act, it must be remembered, 

 involves the complete arc of the sensory and the motor, and in the 

 child the inherent stress is on the motor. Again I quote from 

 Prof. Baldwin : " Just in as far as the motor ingredient of a men- 

 tal content of any kind is large that is, in so far as the sensory 

 ingredient is intense just to this degree also will the direction of 

 attention be secured, and to this degree also will both the ingre- 

 dients be intensified by this act of attention. Intensity draws 

 attention, and attention increases intensity the law of sensory- 

 motor association i. e., every mental state is a complex of sensory 

 and motor elements, and any influence wMch strengthens the one 

 tends to strengthen the other also." 



I have spoken of how the use of the motor side adds new ave- 



