Integrating control generated by positive and negative reinforcement on an operant baseline: Appetitive-aversive interactions

Abstract

The interaction of opposing motivational states was measured within a design in which rats barpressed for food in one stimulus and to avoid shock in another. Tone and light discriminative stimuli (Sds) were counterbalanced over incentive conditions. Extinction eliminated responding when neither Sd was present. To minimize the influence of competing peripheral operants or reinforcer-elicited behaviors during appetitive-aversive interactions, contingency parameters were manipulated to generate similar rates and patterns of barpressing in both Sds and stimulus-compounding tests were administered in extinction. On these tests, rates in tone, light, and tone plus light (T+L) were equivalent. In contrast, when the same reinforcer (i.e., food or shock avoidance) maintained comparable training rates in tone and in light, in testing, T+L controlled double the rates of the single stimuli-strong additive summation. These results were strikingly similar to those of single-incentive experiments concerned with the contribution of excitatory and inhibitory incentive states to the results of stimulus compounding. Simultaneously presenting two Sds whose implicit stimulus-reinforcer (S-S r) contingencies were arranged to make them, respectively, conditioned appetitive and aversive exciters (present experiment) produced test results comparable to those of two Sds whose implicit S-S r contingencies were arranged to make them both conditioned inhibitors. Reciprocal antagonism between these two motive states more than neutralizes them. It appears to produce a negative (i.e., an inhibitory) motive state. © 1989 Psychonomic Society, Inc.