94 I'SYcllol.ocY. 



method,' giving both the shortest times and the most con- 

 stant ones, ought to be aimed at in all comj)arative investi- 

 gations. Herr Lange's oavh muscular time averaged 

 0''.123 ; his sensorial time, ".230. 



These reaction-time experiments are then in no sense 

 measurements of the swiftness of thought. Only when we 

 comi)licate them is there a chance for anything like an 

 intellectual oj^eration to occur. They may be complicated 

 in various ways. The reaction may be withheld until the 

 signal has consciously awakened a distinct idea (Wundt's 

 discrimination-time, association-time) and then performed. 

 Or there may be a variety of jjossible signals, each with 

 a different reaction assigned to it, and the reacter maj- 

 be uncertain which one he is about to receive. The 

 reaction would then hardly seem to occur without a pre- 

 liminary recognition and choice. We shall see, however, 

 in the appropriate chapters, that the discrimination and 

 choice involved in such a reaction are widely different from 

 the intellectual operations of wdiich we are ordinarily con- 

 scious under those names. Meanwhile the simple reaction- 

 time remains as the starting point of all these superinduced 

 complications, it is the fundamental physiological con- 

 stant in all time-measurements. As such, its own variations 

 have an interest, and must be briefly passed in review.* 



The reaction-time varies wdth the mdwidual and his oge. 

 An individual may have it particularly long in respect of 

 signals of one sense (Buccola, p. 147), but not of others. 

 Old and uncultivated people have it long (nearl}^ a second, 

 in an old pauper observed by Exner, Pfliiger's Archiv, vii. 

 612-4). Children have it long (half a second, Herzen in 

 Buccola, p. 152). 



Practice shortens it to a quantity which is for each iiidi- 

 \-idual a minimum be^'ond which no farther reduction can 

 be made. The aforesaid old pauper's time was, after 

 much practice, reduced to 0.1866 sec. (Joe. cit. p. 626). 



* The reader who wishes to know more about the matter wiil tiiid a 

 most faithful compilation of all that has been done, together with miicn 

 original matter, in G. Buccola's 'Legge del Tempo.' etc. See also chap- 

 ter .xvi of "Wundt's Phj'siol. Psychology; Exner in Hermann's Hdbch., 

 Bd. 2, Thl. II. pp. 252-280 ; aJso Ilibot's Contemp. Germ. Psych, 

 chap. VIII. 



