Three-Toed Sloth

Je ne regrette rien

Regret, in decision theory, is the difference between the value of choice you actually made, and that of the best choice you could have made. Usually, decision theory considers agents which try to either maximized the expected value, or maximize the minimum possible value, but there are now some clever methods for learning strategies that minimize the maximum regret an agent will experience, which have some important advantages over those alternatives. (This is something Kris knows much more about than I do, naturally.) Interestingly, there is now also some evidence that this is a better description of what people do than is maximizing expected value --- at least, people with intact orbitofrontal cortices.

Nathalie Camille, Giorgio Coricelli, Jerome Sallet, Pascale Pradat-Diehl, Jean-René Duhamel and Angela Sirigu, "The Involvement of the Orbitofrontal Cortex in the Experience of Regret", Science 305 (2004): 1167--1170 [full text freely available]

Abstract: Facing the consequence of a decision we made can trigger emotions like satisfaction, relief, or regret, which reflect our assessment of what was gained as compared to what would have been gained by making a different decision. These emotions are mediated by a cognitive process known as counterfactual thinking. By manipulating a simple gambling task, we characterized a subject's choices in terms of their anticipated and actual emotional impact. Normal subjects reported emotional responses consistent with counterfactual thinking; they chose to minimize future regret and learned from their emotional experience. Patients with orbitofrontal cortical lesions, however, did not report regret or anticipate negative consequences of their choices. The orbitofrontal cortex has a fundamental role in mediating the experience of regret.

Properly constructing the kind of gambling task used in this study can be tricky, and this week's Science contains a comment claiming these experimenters made a mistake; they reply, and seem to me to have the better of the argument.

Minds, Brains, and Neurons