Sentence:  In that work there was presented for examination a theory of <WSD>Algedonics</WSD> which seemed more adequate to account for our pleasure-pain experiences than any I had met with in the published works of other students of the subject, and which appeared to avoid the difficulties that had heretofore availed to discredit the hedonic theory of Aesthetics. 
Meaning of the word marked with <WSD> tags:  The scientific study of pleasure and pain responses.