Comment on "The involvement of the orbitofrontal cortex in the experience of regret".

of the Orbitofrontal Cortex in the Experience of Regret’’ Regret is an emotion that accompanies negative outcomes to decisions for which we have been responsible (1). Given a choice between two gambles, subjects will experience regret if the unchosen gamble yields a higher reward than the chosen gamble (2). Camille et al. (3) hypothesized that the anticipation of regret is useful for steering decision-making and, to this end, tried to show that normal controls perform better on a gambling task than patients with lesions of the orbitofrontal cortex (OFC), who do not appear to experience regret. However, the parameters of their gambling task raise the possibility of alternative explanations. Camille et al. set out to Btest the prediction that advantageous choice behavior depends on the ability to anticipate and hence minimize regret[ (3). Yet it is not generally true of gambling tasks that anticipated regret is helpful, and it is especially not true in the task they describe. As will be made clear below, it is only because of the design of their task that they obtained the apparent result that normal controls (who experience regret) outperformed the OFC patients (who do not experience regret). Specifically, the authors present subjects with two gambles; the subject picks the one she wants to play, and in the Bcomplete feedback[ condition she sees both its outcome and the outcome of the unchosen gamble. Camille et al. suggest that OFC patients make their choice largely based on the expected value (EV) of the two gambles, whereas normal controls also take into account a measure of anticipated regret, which encodes the difference between what they might get and what they might have gotten. In their notation, when presented with two gambles, the anticipated regret from choosing gamble 1 is r 0 ky 2 – x 1 k – k y 1 – x 2 k, where x 1 and y 1 are the possible outcomes of gamble 1 and x 2 and y 2 are the possible outcomes of gamble 2 (x 1 and x 2 are always higher than y 1 and y 2 ). Minimizing anticipated regret means avoiding the possibility of a big negative value when, in the future, you compare what you got to what you could have had. To understand the role of anticipated regret in decision-making, we simulated the game with the exact parameters prescribed by Camille et al. Possible outcomes consist of any pair of the values þ50, –50, þ200, and –200 associated with different outcome probabilities (0.8, 0.2, or 0.5). Because of the structure of this task, a gambler who makes decisions based only on the highest EV will outperform one who makes decisions based on anticipated regret; they will earn averages of 1930 and 1447, respectively (P G 4 10; t 0 4.7; weighted combinations of EV and anticipated regret will show intermediate performance) (Fig. 1A). In other words, as every