No. 435-] 



A'( > EES . IM) LITER A EC 'RE. 



207 



experiments are reliable and the sources of error known, is not to be 

 damaged by a hundred objections such as the a priori impossibility 

 of the measurement of psychic magnitudes" (p. 154), and so forth. 

 This will please the novice, but its flippancy will certainly mislead 

 him. If psychic facts cannot be measured, then they have not been 

 measured, and their measure is not given by the psycho-physic form- 

 ula. It therefore behooves the serious scientist to enquire either 

 what it is whose magnitudes the law does express, or else, what error 



ment of the psychic to be impossible. The flat contradiction must 

 not exist ; above all it should not be exhibited for the delight and 

 mystification of the readers of The Presbyterian Review. 



Among the experimental papers the best is the well-known one on 

 Types of Reaction, reprinted from The Psychological Review. Here 

 Professor Baldwin and Mr. W. J. Shaw offer a different interpretation 

 of sensory and motor reaction times from that suggested by Lange, 

 the originator of those terms. Lange (and Wundt) believed that the 

 motor reaction time is shorter because for it the nervous paths are 

 subexcited beforehand and so prepared for swift discharge. Where- 

 as Professor Baldwin and Mr. Shaw prove that the motor reaction 

 time is in many persons not shorter , but longer than the sensory, 

 and that this latter is itself very variable, according as one or another 

 sense receives the stimulus. Thus the distinction is not between 

 motor and sensory but between the various sensory, reaction times 

 (visual, acoustic, olfactory, et at). The shortest reaction time is 

 given by that sense, which furnishes the images most used in the per- 

 son's thought, and which therefore gives habitually the cues for motor 

 discharges. Thus with a visualizer. visual stimuli will give the most 

 rapid reaction time; with an auditeur. auditory stimuli. The so- 



habitually initiated by motor images : to whatever sense the stimulus 

 is given, the impulse has to go to the motor-image-centres, and then 

 to the muscles. Thus its course is indirect, but since in a moteur it 

 cannot be shortened (that is, all his reactions are really motor), the 

 increased speed of discharge due to the subexcitation of the motor- 

 image-centres in the reactions which are avowedly motor will give 

 these the advantage in time over the reactions which are (errone- 



to be swifter, because presumably these authors say, he had mostly 

 moteurs to experiment on (the commoner type) and because he 



type of 



