Another physiological comparison lends further support to the present theory. The theory has said nothing so far about why it should be that when N and V occur simultaneously in the mind, the body should respond by repeated exhalatory vocalization and the other physiological symptoms of humor perception. This would seem to be a mystery, until one considers other cases with similar physiological responses. Repeated exhalatory vocalization is present not only in laughter but also in sobbing or crying and also in gasping in pain. If crying, laughing, and gasping in pain are considered as a natural class, the odd element in the group would seem to be laughter, since it is pleasant, while crying and gasping in pain are not. However, in the present theory, as opposed to other theories, laughter contains an element of emotional pain, namely the V interpretation, that something one cares about has been violated. This ties laughter together with crying and gasping in pain, in a way that theories of laughter and humor which do not include some element analogous to pain will fail to capture. The basic physiological similarity among the three would make sense given an underlying affective similarity, which the present theory makes possible.
Taking this for granted, then, the physiological response of laughter is a consequence of its related mental state in essentially the same way that crying and gasping in pain are derived from their related mental states, that is, according to some kind of generalized pain response, which takes slightly different forms in the different cases.13 The present theory does not explain why the generalized pain response should have this physiological consequence -- this should be explained by some more general theory, after all -- but the relationship of laughter to other pain-responses seems clear: they all contain an emotional violation.