ATTENTION. 429 



its climax^ the movement we stand ready to execute escapes from the 

 control of om will, and we register a wrong signal. In these other ex- 

 periments, in wnich a warning foretells the moment of the stimulus, it 

 is also plain that attention accommodates itself so exactly to the lat- 

 ter's reception that no iooner is it objectively given than it is fully 

 apperceived, and with th<^ apperception the motor discharge coin- 

 cides.''''* 



Usually, when the impfessiou is fully anticipated, atten- 

 tion prepares the motor centres so completely for both 

 stimulus and reaction that the only time lost is that of the 

 physiological conduction downwards. But even this inter- 

 val may disappear, i.e. the stimulus and reaction ma}' be- 

 come objectively contemporaneous ; or more remarkable 

 still, the reaction may be discharged before the stimulus has 

 actually occurred.t Wuudt, as we saw some pages back 

 (p. 411), explains this by the effort of the mind so to react 

 that we may feel our own movement and the signal which 

 prompts it, both at the same instant. As the execution of 

 the movement must precede our feeling of it, so it must 

 also precede the stimulus, if that and our movement are to 

 be felt at once. 



The peculiar theoretic interest of these experiments 

 lies in their shoiving expectant attention and sensation to he 

 continuous or identical processes, since they may have identical 

 motor effects. Although other exceptional observations 

 show them likewise to be continuous subjectively, Wundt's 

 experiments do not : he seems never, at the moment of 

 reacting prematurely, to have been misled into the belief 

 that the real stimulus was there. 



As concentrated attention accelerates perception, so, 

 conversely, perception of a stimulus is retarded by anything 

 which either baffles or distracts the attention with which we 

 aA\*ait it. 



"If, e.g., we make reactions on a sound in such a way that weak 

 and strong stimuli irregularly alternate so that the observer can never 

 expect a determinate strength with any certainty, the reaction-time for 

 all the various signals is increased,— and so is the average error. I 



* Op. cit. II. 239. 



f The reader must not suppose this phenomenon to be of frequent 

 occurrence. Experienced observers, like Exner and Cattell, deny having 

 met with it in their personal experience. 



