The Concept of Inhibition - in Cognition

Everyone knows what inhibition is-and that creates a very real problem. The idea is so ingrained that it is difficult to discuss it as a scientific concept without contamination from existing world knowledge. Yet discussing it is exactly what cognitive scientists have been attempting to do with renewed vigor in the recent past, owing to a t least three factors: the growth of cognitive neuroscience, developments in cognitive modeling, and newly described cognitive phenomena. Beginning with the phenomenon of negative priming (for reviews, see Fox, 1995; May, Kane, & Hasher, 1995; Tipper, 2001) and spurred by two influential books that appeared in quick succession just over a decade ago (Dagenbach & Carr, 1994; Dempster & Brainerd, 1995), interest in cognitive inhibition grew. Of course, the desire to mesh cognition with neuroscience also has provided a powerful impetus for understanding the place of inhibition in the current conceptualization of mind and brain. This interest is well illustrated by the inclusion of inhibition as one of only 16 core concepts in a recent effort to grapple with concepts-free of empirical research findings-that are fundamental to memory (Roediger, Dudai, & Fitzpatrick, in press). This chapter is intended as a broad introduction to the concept of inhibition in cognition and consequently to this book as a whole. For this reason, I take no strong stand on the value of the concept (although I have expressed a skeptical point of view elsewhere; see MacLeod, in press; MacLeod, Dodd, Sheard, Wilson, & Bibi, 2003). In this chapter, the goal is to set out the issues involved in the empirical study and theoretical understanding of the concept of inhibition as it applies to the operation of cognition. So I begin with what this chapter is and is not about. This chapter is not about the neural concept of inhibition: It is accepted that neurons certainly can inhibit each other. This chapter also is not about the physical-response concept of inhibition: It is