Evaluating the influence of C/t on sensitivity to relative S+ production rate

Humans and nonhumans tend to display undermatching for stimuli positively correlated with reinforcement (i.e., S+s). C/t ratios are a method of quantifying the temporal informativeness of S+s, which may help account for varied levels of sensitivity to relative S+ production rate. However, researchers have yet to investigate the effects of C/t on choice in this context. Therefore, the purpose of the current study was to evaluate the influence of C/t on sensitivity to relative S+ production rate in a concurrent observing-response procedure with human participants. Each participant experienced eight conditions in which C/t and relative S+ production rate varied. Specifically, four relative S+ production rates were programmed with either low or high C/t. We evaluated differences in sensitivity by comparing multilevel regression models with and without C/t as a fixed-effect parameter and by comparing fits of the generalized matching equation across each participant's low- and high-C/t conditions. Our results suggest that participants' behavior was sensitive to relative S+ production rate. Surprisingly, participants' behavior tended to be more sensitive in their low-C/t conditions relative to their high-C/t conditions, but the magnitude of differences varied across participants.