Despite the simplicity of Kurzban et al.'s framework, we argue that important information is lost in their simplification. We discuss research on delay of gratification and self-regulation that identifies key situational and psychological factors affecting how people represent rewards and costs. These factors affect the expected utilities of behavioral options and thus dramatically influence whether individuals persist on a difficult task.

The commentaries on our target article are surprisingly sympathetic to our overall approach to explaining subjective effort, though disagreement with particulars inevitably emerged. Here, in our response, we first review the few disagreements concerning the basic structure of our proposal, highlighting areas in which little or no resistance was voiced. Opposition to the assumptions that underlie our opportunity cost model is noticeably limited. Areas of genuine disagreement, however, include: (1) the inputs to and outputs of the relevant decision-making systems; (2) how to interpret data regarding individual differences in performance; (3) how to explain persistence on tasks that give rise to the sensation of subjective effort; and (4) the details of the relevant neuropsychological systems. Throughout we point to empirical issues raised by the commentaries and suggest research that will be useful in arbitrating points of disagreement.