BEGINNINGS OF INTELLIGENCE 175 
for the “increased energy of the pleasure process” to flow 
“into the channels of the movement associated with pleasure” 
(that is, I take it, the movement which brings pleasure) 
ig by no means evident. There is, I think, no primary ten- 
dency,,as Spencer and Bain seem to think, for the nervous 
discharge to take the direction of the organ from which the 
pleasure is derived. Animals, it is true, move so as to 
bring an organ which is pleasantly stimulated again under 
the action of the stimulus, but this is often due to the dis- 
charge going mainly to a quite different part of the body, 
such as distant appendages, instead of to the part directly 
affected. 
The theory of heightened nervous discharge as expounded 
by Spencer, Bain and Baldwin, fails to give us, I think, the 
desired explanation of the acquirement of individual ac- 
commodations, and one naturally turns to other theories of 
the psycho-physiology of pleasure and pain for light. Here, 
however, we are led into a veritable quagmire of psychological 
speculation, for there are few fields in which there are so 
many and so fundamental differences of opinion among 
competent psychologists. The physiological concomitants 
of pleasure and pain have afforded a subject of numerous 
laboratory studies and almost no end of theories. There 
is good evidence that pain sensations are produced by 
the stimulation of specific nerves, but as regards the 
physiological states accompanying pleasure and pain the 
results of experiments as well as opinions based on them 
are very discordant. And it is difficult to see how most 
of the pleasure-pain theories. would help us to explain 
the mechanism of accommodation even if they were 
established, so that the outlook for the solution of the 
problem as it is commonly formulated does not seem, at 
present, an encouraging one. 
