Reconsidering conditioned inhibition

Conditioned inhibition is a fundamental component of contemporary learning theory. Our selective review of the literature defines the term conditioned inhibition on three levels-operational, behavioral, and theoretical-in order to evaluate the utility of the construct. Although consensus definitions are found at the operational and behavioral levels, the principal disagreement exists, not surprisingly, at the theoretical level. The comparator hypothesis suggests that the concept of inhibition is superfluous because behavior that is indicative of inhibition can be explained more parsimoniously by noninhibitory theoretical mechanisms. Furthermore, the findings that inhibition is less pervasive than and not always mutually exclusive with excitation suggest that the original view of inhibition as the opposite of conditioned excitation is no longer viable. However, rejection of the original conception of inhibition does not invalidate the theoretical utility of inhibition as a construct in other paradigms (e.g., occasion setting). (C) 1999 Academic Press.