Disappointment and are not the same feeling. Disappointment is getting less than you expected; regret is recognizing that a different action of yours would have done better. In people the tracks regret, and people with damage there do not express it. So one lab built a rat task where skipping a cheap offer and then meeting an expensive one creates exactly that structure. What did the rats do?
Four things happened at once, and all of them fit. On encountering a high-cost choice right after skipping a low-cost one, rats looked backward toward the option they had passed up. Cells in both the orbitofrontal cortex and the represented the rather than the present one. The rats were then more likely to wait out the long delay, and they rushed through eating the food afterward.
Disappointment and regret are often used interchangeably and are structurally different. Disappointment entails recognizing that you did not get the value you expected. Regret entails recognizing that an alternative action, one you could have taken, would have produced a better outcome.
The human evidence points at one region. The orbitofrontal cortex is active during expressions of regret, and people with damage there do not express it. In rats and nonhuman primates both the orbitofrontal cortex and the ventral striatum have been implicated in reward computations, which makes them the places to look.
The task used an economic framework. Rats encountered wait or skip choices for delayed delivery of different flavors, and the researchers recorded neural ensembles from both regions. Economically, meeting a high-cost choice straight after skipping a low-cost one is the situation that should induce regret, because the animal’s own earlier action is what cost it.
In exactly those situations four things coincided. The rats looked backward toward the lost option. Cells in the orbitofrontal cortex and the ventral striatum represented the missed action. The rats became more likely to wait for the long delay. And they rushed through eating the food once it finally came. No single one of those would be convincing, and together they trace the shape of regret. Hold the word loosely, though: regret here is a structural definition applied to a choice, and nothing in the data reports how a rat feels.
wat. A rat that skipped the cheap offer and hit an expensive one glanced back at what it had passed, and its brain coded the road not taken.
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The convergence is what carries it. A backward glance alone would be a curiosity, and a backward glance plus cells coding the forgone action plus a changed later choice is a pattern with the shape of regret.
How do we know?
Steiner and Redish recorded neural ensembles from orbitofrontal cortex and ventral striatum while rats faced wait or skip choices for delayed delivery of different flavors, within an economic framework.
What is still unknown
Regret here is defined economically by the structure of the choice, not reported by the animal. The behavior and the neural activity are consistent with regret and cannot establish that a rat feels anything.
Learn something?
Where to next
Will a rat play hide-and-seek with you for nothing but the game?rats
Would you notice if your own choice were swapped?decision-making
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