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SCIENCE. 



[N. S. Vol. XX. No. 519. 



physics to psychology, and a widening of 

 the area of experimental work. Thus in 

 the Studien there are about twice as many 

 articles on sensation, psychological and 

 psychophysical, as there are on perception ; 

 in the American Journal, the articles on 

 perception are 'more numerous than those 

 on sensation; in the Psychological Review 

 there are, roughly, three articles on percep- 

 tion for every two on sensation, while the 

 strictly psychophysical papers may almost 

 be counted upon the fingers of one hand; 

 and the Armee psychologique, if I have 

 counted aright, has practically as many ar- 

 ticles on memory as it has on perception, 

 and more of either than it has on sensa- 

 tion, while the spirit of the work has, from 

 the first, been adverse to psychophysies. 

 Or again, the contents of the American 

 Journal may, with some manipulation, be 

 brought under the same headings that 

 served for the Studien, save that one addi- 

 tional caption must be made for studies of 

 voluntary movement (other than reac- 

 tions) and of the experiences of effort and 

 fatigue ; while those of the Zeitschrift and 

 the Psychological Review require at any 

 rate three or four new rubrics, to cover 

 work done upon mental inhibitions, the 

 process of learning, motor automatisms 

 and motor dispositions, habit, etc. I do 

 not wish to labor this point, even if I must 

 leave it with some sense of injustice to the 

 periodicals under review. You know, with- 

 out my telling you, and I knew,' without 

 going to the magazines, that the course of 

 experimental psychology in recent years 

 has been away from simple psychophysical 

 determinations, ■ and towards introspective 

 analysis; and that the experimental 

 method has been continually extended 

 from the simpler processes to the more com- 

 plex— whether -to complexes hitherto un- 

 touched by experiment, or to unfamiliar 

 phases of familiar mental formations. All 

 that a study of the journals can do is to 



quantify and define these facts. I should 

 like to add, however, that their study has 

 brought home to me, in a very vivid way, 

 the immense complexity and far-reaching 

 interconnection of the mental life. The 

 contents of experimental papers are often- 

 times so varied that only a classification a 

 posteriori is possible ; and, oftentimes again, 

 results that are but incidental to the given 

 topic of investigation prove later on to be 

 fundamental for problems from which this 

 topic had seemed disconnected and remote. 



So much, then, by way of preparation. 

 Let us now, in the light of it, attempt to 

 formulate the present problems of experi- 

 mental psychology. You will remember 

 that I am speaking of experimental psy- 

 chology sensu stricto—oi. the experimental 

 investigation of the normal, adult, human 

 consciousness. I wish that I could proceed 

 systematically. But, in the existing condi- 

 tion of the science, it is better to be topical. 

 We may, however, begin in a quasi-system- 

 atic way, by considering the three funda- 

 mental problems of sensation, affection and 

 attention. 



(1) Sensation. — The senses, viewed from 

 the standpoint of psychological knowledge, 

 fall into three principal groups. We know 

 a great deal about sight and hearing; we 

 know a good deal about taste, smell and 

 the cutaneous senses; of the organic sensa- 

 tions, with a very few exceptions, we know 

 practically nothing. There is work to be 

 done— I say this emphatically— in every 

 field ; there is probably no single chapter in 

 sense psychology that may not, with advan- 

 tage, be reopened. Nevertheless, we know 

 a great deal about sight and hearing; the 

 literature of these senses is voluminous; 

 advance in our knowledge lies (I am speak- 

 ing in the large and quite roughly) in the 

 hands of the few experts who have occu- 

 pied themselves particularly with visual 

 and auditory problems. And we know a 

 good deal about taste, smell and the cuta- 



