THE REACTION-TIME OF GONIONEMUS MURBACHII 

 TO ELECTRIC AND PHOTIC STIMULI. 1 



ROBERT M. VERKES. 

 CONTENTS. 



PAGE. 



Problems and Methods 84 



Reaction-Time to Electric Stimuli 85 



Reaction-Time to Photic Stimuli 86 



Relation of Reaction-Time to Region Stimulated 88 



Reaction-Time of Tentacles 89 



Relation of Quality of Stimulus to Time of Reaction 91 



Absolute and Relative Variability 92 



PROBLEMS AND METHODS. 



The reaction-time method as applied to the study of the func- 

 tioning of the nervous system has already given us certain im- 

 portant facts in human neuro- physiology, and it promises much 

 more valuable results when its application to representatives of 

 the various animal phyla makes a comparative survey of the time 

 relations of neural processes possible. The value of reaction- 

 time studies lies chiefly in the knowledge which they give us of 

 the biological significance of the nervous system. " Certainly 

 they are not important as giving us knowledge of the time of per- 

 ception, cognition or association, except in so far as we discover 

 the relations of these processes, and the conditions which are most 

 favorable for them. To determine how this or that factor in the 

 environment influences the activities of the nervous system, and 

 in what way system may be adjusted to system or part process 

 to whole is the task of the reaction-time investigator." 



For the reaction-time measurements which furnish the ma- 

 terial of this paper chronoscopic methods were employed. All 

 reactions to light were measured by means of a stop watch read- 

 able to tenths of a second, but for the reactions to electric stimuli, 

 which were very much quicker, it was necessary to make use of 



1 From the Marine Biological Laboratory, Woods Holl, Mass. 



2 Yerkes, Robert Mearns : "The Instincts, Habits and Reactions of the Frog." 

 Harvard Psychological Studies, Vol. I., 1903, p. 509 {Psychological Review Mono- 

 graph Supplement, Vol. IV.). 



84 



