Testing problems in J.A. Gray's personality theory: A commentary on Matthews and Gilliland (1999)

In their comparative review of H. J. Eysenck’s arousal and J. A. Gray’s reinforcement theories of personality, Matthews and Gilliland [(1999) Personality and Individual Differences, 26, 583–626] concluded that “Cognitive constructs may be more appropriate than biological ones for explaining the majority of behaviours, so that explanations of the kind offered by the Eysenck and Gray theories are relevant to a restricted range of phenomena only” (p. 620). In this commentary, I address a number of problems in Gray’s account of the Behavioural Inhibition System (BIS) and the Behavioural Approach System (BAS) that need to be tackled before we can conclude that cognitive accounts of personality should supersede, rather than complement, biologically-based ones. I focus on two broad sets of issues. (1) Practical (operational) problems, that call for further experimental work, relating to: (a) BIS/BAS and conditioning/learning; (b) reinforcement parameters (i.e., defining reward/punishment, reinforcement expectancies, schedules of reward, sources of reinforcement, cues versus feedback); and (c) psychometric measures of BIS/BAS functioning. (2) The theoretical nature of BIS/BAS effects, that call for an elaboration of Gray’s theory. I propose a two-process model that postulates that the BIS and BAS exert two effects: facilitatory, the BIS mediates responses to aversive stimuli, the BAS to appetitive stimuli; and antagonistic, the BIS and BAS impair responses mediated by the alternate reinforcement system. Specific directions for future research are given. I conclude that, in several crucial respects, Gray’s reinforcement theory has yet to be adequately tested; and that closer attention to operational definitions, and the mutual interplay of the BIS and BAS, may enhance its experimental precision.