432 PSYCHOLOGY. 



nected with other properties of our attention. The effort of the latter 

 is aecompanied by various corporeal sensations, according to the sense 

 which is engaged. The innervation which exists during the effort of 

 attention is therefore probably a different one for each sense-organ." * 



Wundt then, after some theoretical remarks which we 

 need not quote now, gives a table of retardations, as fol- 

 lows : 



Retardation. 



1. Unexpected strength of impression : 



a) Unexpectedly strong sound , 0.073 



h) Unexpectedly weak sound 0.171 



2. Interference by like stimulus (sound by sound) 0.045 t 



3. Interference by unlike stimulus (light by sound) 0.078 



It seems probable, from these results obtained with ele% 

 mentary processes of mind, that all processes, even the 

 higher ones of reminiscence, reasoning, etc., whenever at- 

 tention is concentrated upon them instead of being diffused 

 and languid, are thereby more rapidly performed. | 



Still more interesting reaction-time observations have 

 been made by Miinsterberg. The reader will recollect the 

 fact noted in Chapter III (p. 93) that reaction-time is 

 shorter when one concentrates his attention on the exjjected 

 movement than when one concentrates it on the expected 

 signal. Herr Miinsterberg found that this is equally the 

 case when the reaction is no simple reflex, but can take 

 place only after an intellectual operation. In a series of 

 experiments the five fingers were used to react with, and 



* Op. cit. pp. 241-5. 



t It should be added that Mr. J. M. Cattell (Mind, xi. 33) found, on 

 repeating Wundt's experiments with a disturbing noise upon two practised 

 observers, that the simple reaction-time either for light or sound was 

 hardly perceptibly increased. Making strong voluntary concentration of 

 attention shortened it by about 0.013 seconds on an average (p. 240). 

 Performing mental additions whilst waiting for the stimulus lengthened it 

 more than anything, apparently. For other, less careful, observations, 

 compare Obersteiner, in Brain, i. 489. Cattell's negative results show how 

 far some persons can abstract their attention from stimuli by which oth- 

 ers would be disturbed. — A Bartels (Versuche iiber die Ablenkung d. Auf- 

 merksamkeit, Dorpat, 1889) found that a stimulus to one eye sometimes 

 prevented, sometimes improved, the perception of a quickly en.sulDg very 

 faint stimulus to the other. 



XC{. Wundt, Physiol. Psych., 1st ed. p. 794. 



