Rats express behavior consistent with regret, reports a paper published online this week in Nature Neuroscience.
Redish and colleagues trained rats to do a “restaurant row” task in which they ran in a circle past a series of four reward zones. The food dispenser in each zone provided a different flavored food, which was constant across the experiment. Every time a rat stopped into a reward zone, a tone indicated how long it would have to wait in that zone to receive a specific flavor reward. The rat had to choose whether to stay or go, based on how much it liked that food and how long it would have to wait.
Sometimes the rat skipped a reasonably good combination of flavor and wait, only to find out that the next zone had a much worse offering. In these situations, rats often looked back at the reward zone they had just passed over, were more likely to wait out a long delay at the next zone, and rushed through consuming the reward-behaviors consistent with the expression of regret.
Brain structures that are known to encode information about expected outcomes also encode signals about missed opportunities. Neurons in the orbitofrontal cortex and ventral striatum showed flavor-specific activity patterns when the rats expected to receive a reward and these characteristic patterns were also seen when the animals looked back at a reward zone where they could have received that flavor reward. This work suggests that processes similar to regret can modify decision making in rodents.