GENERAL CONDITIONS OF BRAIN-ACTIVITY. 93 



one keeps one's mind as intent as possible upon the ex- 

 pected signal, and ' purposely avoids ' * thinking of the move- 

 ment to be executed ; in the ' extreme muscular ' Avay one 

 ' does not think at all ' f of the signal, but stands as ready as 

 possible for the movement. The muscular reactions are 

 much shorter than the sensorial ones, the average differ- 

 ence being in the neighborhood of a tenth of a second. 

 Wuudt accordingly calls them ' shortened reactions ' and, 

 with Lange, admits them to be mere reflexes ; whilst the 

 sensorial reactions he calls * complete,' and holds to his 

 original conception as far as they are concerned. The 

 facts, however, do not seem to me to warrant even this 

 amount of fidelity to the original "Wundtian position. 

 When we begin to react in the ' extreme sensorial ' way, 

 Lange says that we get times so very long that they must 

 be rejected from the count as non-typical. " Onl}^ after 

 the reacter has succeeded by repeated and conscientious 

 practice in bringing about an extremely precise co-ordina- 

 tion of his voluntary impulse with his sense-impression 

 do we get times which can be regarded as typical sensorial 

 reaction-times.'' X Now it seems to me that these excessive 

 and ' untypical ' times are probably the real ' complete times,*' 

 the only ones in which distinct processes of actual percep- 

 tion and volition occur (see above, pp. 88-9). The tj'picaJ 

 sensorial time which is attained by practice is probably 

 another sort of reflex, less perfect than the reflexes pre- 

 pared by straining one's attention towards the movement. § 

 The times are much more variable in the sensorial way 

 than in the muscular. The several muscular reactions 

 differ little from each other. Only in them does tiie phe- 

 nomenon occur of reacting on a false signal, or of reacting 

 before the signal. Times intermediate between these two 

 types occur according as the attention fails to turn itself 

 exclusively to one of the extremes. It is obvious that Herr 

 Lange's distinction between the two types of reaction is a 

 highly important one, and that the 'extreme muscular 



* Loc. cit. p. 488. t ^<^- c*'^- P- 487. |Zoc. cU. p. 489. 



§ Lange has an interesting hypothesis as to the brain-process concerned 

 in the latter, for which I can only refer to his essay. 



