678 EXPERIMENTAL PSYCHOLOGY 



its importance for the primary perception of self; when we re- 

 member the widespread character of the organic reaction set up 

 by any sensory stimulus; when we realize that some psycholog- 

 ical systems have recourse to it from beginning to end, while others 

 (Wundt's recent Grundziige is an example) practically ignore 

 it; when we remember that certain questions of prime systematic 

 importance hinge upon it, the question of the duality of the 

 conscious elements, of the relative range of sensation and image, 

 of what is called affective memory, and so on, we can hardly fail 

 to see that here is a great gap in our psychological knowledge, the 

 rilling of which calls for a persistent application of the experi- 

 mental method. Of all problems in the psychology of sense that are 

 now before us, the problem of the number, nature, and laws of 

 connection of the organic sensations appears to me to be the most 

 pressing. 



In the domain of psycho-physics, I see no single problem of su- 

 preme import, but rather a need for patient, continuous work by 

 the methods already formulated. The inherent aim of psycho- 

 physical investigation is, as I have said, the determination of the 

 psycho-physical constants. Now it is by no means difficult to vary 

 a psycho-physical method, and so to set up a claim of originality; 

 but it requires patience and some self-sacrifice to work through 

 a psycho-physical method to the bitter end. What we now want 

 is less ingenuity and more work, accurate, continuous work all 

 along the line. We have methods and we have formulae. Let us 

 give them a thorough test. The results will be of extreme value 

 for psycho-physics, and no one need fear that they will be barren 

 for psychology. On the contrary, no small part of our analytical 

 knowledge of the higher processes, as they are called, processes 

 of judgment, of comparison, of abstraction, derives straight from 

 the method-work of psycho-physics. It would, in my opinion, be 

 time and energy well spent, if every existing laboratory were to 

 undertake what one might term the routine work of testing-out, 

 without modification, one or other of the classical methods. 



I am aware that psycho-physics trenches upon large problems. 

 I ought, indeed, to be keenly alive to these problems, seeing that 

 for the past three years they have occupied me, with but little 

 intermission. There is the great problem of mental measurement 

 itself; there are the minor problems of the validity of the differ- 

 ence limen, the equality of just noticeable differences, the range 

 of Weber's Law, the correlation of functional constants, and what 

 not. If I were speaking of the history of experimental psychology, 

 and not of its present status, I might hope to show you that more 

 has been done towards a solution of these problems than the cur- 

 rent statements in text-books and magazines would lead one to 



