SINGLE SYNAPSE : TWO NEURONS 



39 



t r = to lOg (1 



a 



h 



-) 



piogS/K 



(2) 



to represent the experimentally determined relation between t r and 

 S . The extent to which this does so in some cases for which data are 

 available may be seen in Figures 1, 2, and 3 where experimental data 



BERGEN ANO CATTELL 

 VISUAL DATA 



O SUBJECT B 

 • SUBJECT C 



STIMULUS INTENSITY S- 



Figure 1. — Comparison of theory with experiment: dependence of delay of 

 reaction upon intensity of the stimulus for visual stimuli. Curves, theoretical 

 predictions by equation (2) ; points, experimental. (Visual data from Cattell, 

 1886.) Abscissa, intensity (on logarithmic scale) of stimulus; ordinate, interval 

 between presentation of stimulus and occurrence of response. 



(points) and theoretical predictions (curves) are shown for each of 

 a number of rather different types of stimuli. The details are given 

 in the legends. 



In general, we cannot expect that the chain from receptor to 

 effector involved in the reflex will contain so small a number of ele- 

 ments. But certainly this demands first consideration since it is the 

 simplest possible mechanism. And even if the chain were known to 

 contain a larger number of neurons, the slowest synapse in the series 

 will tend to govern by itself the temporal form of the response, so 

 that if the remaining synapses are relatively fast, the equation just 

 deduced will still provide an adequate description of the experimental 

 situation. 



If a stimulus S is presented for too short a time t , e will not 



