Sensitivity to Molar Feedback Functions: A Test of Molar Optimality Theory

Molar optimality models assume that any reward schedule can be described by a molar feedback function, which is the relation between average response rates and average reinforcement rates enforced by that particular schedule. This molar feedback function is considered, by optimality models, to be a sufficient description of the schedule for the prediction of steady-state molar performance. In this article we challenge the fundamental assumption of all molar optimality modelsthat animals are directly sensitive to this molar feedback function. We found that animals were sensitive to the schedule conditions in effect, especially at the molecular level of postfood time, but they were not directly sensitive to the slopes of any ofthe molar feedback functions that we manipulated. Our data do not simply represent a failure to maximize a particular utility function so that this form of the function requires alteration. Rather, they demonstrate that animals may not be sensitive to the molar rates of responding and reinforcement described by the molar feedback functions. Our animals were sensitive to the schedules at a molecular level, and it is to this molecular level that we should direct our attention.