THE SUMMATION-IRRADIATION THEORY OF 
PLEASURE-PAIN 
Professor Herrick’s theory of pleasure-pain is significant in 
that it states the physiological mechanism of tension and read- 
justment which are required by the James-Lange theory of 
emotion^ especially in its revised form as stated by Professor 
Dewey and Professor Fite.^ 
There is no separate apparatus for feeling. With each act of 
the conscious organism there are changes of tone comparable to 
the accessory vibrations constituting the timber of a musical 
instrument. These are associated with vascular changes (varia- 
tion in the pressure of the blood in the capillaries and probably 
in the brain) . The disturbance of equilibrium in these and other 
ways produces the change in feeling tone, varying from mere 
somatic feeling to the explosive excitement of certain sense irra- 
diations. 
All sensations are experienced as pleasurable in proportion as 
they relieve existing strain or overcome resistance; as painful 
in proportion as they fail to relieve such strain or overcome 
accumulated resistance. In other words, pain means congestion, 
contraction, obstruction, disadaptation, a disproportionateness of 
stimulus to the conveying power of the organ. Pleasure means 
diffusion, expansion, irradiation, discharge. In both cases there 
is summation of stimuli, but in the case of pain this summation 
finds no overflow or discharge, or the process of inhibition is 
carried to the point where the subsequent discharge results in a 
further mal-adjustment. 
Often an interval of one or two seconds may elapse after the sensa- 
tion is perceived before pain appears. These cases, so often quoted as 
proving the distinct nature of pain, are in one respect fallacious. When 
a nerve fiber is penetrated by a pin the pain is nearly, if not quite, as 
promptly felt as the touch. When the finger is struck by a hammer the 
pain is frequently long delayed. But the acme of pain in that case is 
' Cf. James, Psychology, vol. 2, p. 451; Psychological Review, vol. 1, 1894, p. 516; 
Fite, Psychological Review, vol. 10, 1903, p. 639; M’Lennan, Psychological Review, vol. 
2, 1895, p. 466. 
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