Individual differences in conditioned reward: The observing procedure

In observing response procedures, participants respond to produce a stimulus (CS+) that is correlated with the occurrence of reinforcement even though there is no contingency between the observing response and reinforcement. The rate of responding to produce the CS+ is considered a measure of the conditioned reinforcement and considerable individual differences have been observed on this measure. The goal of this study was to examine individual differences in conditioned reinforcement among 36 undergraduates selected for self-reported levels of behavioral approach (BAS). The procedure involved tones as conditioned stimuli, one of which was correlated with receiving money (CS+), the other was uncorrelated with reward (CS0). Extending prior work, participants acquired differential observing for CS+ vs. CS0, and there were marked individual differences in observing behavior. Contrary to our prediction that high BAS participants would demonstrate greater conditioned reinforcement, group differences were not reliable overall. There was some evidence of more rapid acquisition of conditioned responding among high- compared to low-BAS participants. Possible reasons for the relatively modest association are discussed. The present data call attention to potential ties between the largely separate literatures of observing responses as measures of conditioned reinforcement and reinforcement-based models of personality.