302 THE GROWTH OF THE BRAIX. 



response to it a movement is made, the time elapsing 

 between the first and second event is the reaction time. 

 The figures in Table 57 represent such times, and their 

 diurnal variation is the feature to be illustrated. Of 

 course, between the initial and final events various 

 complicated processes may be intercalated. For 

 example, the stimulus may be used as the signal 

 for a problem in mental arithmetic, or the association 

 of simple ideas, at the conclusion of which the final 

 reaction is to be made, and thus the total time of the 

 reaction is modified by the speed with which this inter- 

 mediate process is carried on. 



TABLE 57. SHOWING THE LENGTH OF TIME REQUIRED FOR 

 REACTIONS UNDER Two SETS OF CONDITIONS, AND AT 

 DIFFERENT HOURS OF THE DAY. 



The experiments were made at the University of Kasan, Russia, 

 by Ostanikow and Gran, medical students. Tichon was a labora- 

 tory servant, eighteen years of age ; Galkin, a peasant, sixty-five 

 years of age. 



ooi of a second. 



From this it appears that under the conditions of the 

 experiment, the reaction time, both simple and complex, 

 tended to be longest in the afternoon and shortest in 



