¹⁷I refrain from trying to rigorously define pleasure in this framework, but obviously an RPE where the obtained reward is greater than expected is a good candidate. In fact, in experiments with participants playing a gambling game, reward prediction error was a strong predictor of the participants’ well-being (Rutledge et al., 2014), presumably including both pleasure and suffering symmetrically; however, the average level of reward had a strong effect as well. Alternatively, Carver (2003) has proposed that the function of the pleasure system is to signal that the current task has been accomplished, and the system can direct its resources to other tasks. The neurobiology of pleasure and pain is reviewed by Leknes and Tracey (2008).