"On entry into each restaurant, mice were informed of the delay that they would be required to wait to get the food from that restaurant."

That is quite some customer service for nonhuman animals (sic).

Understandably you wish to learn more about the whole dining experience of mice but there is one thing. We must first analyze 'regret', okay?

Regret can be defined as the subjective experience of recognizing that one has made a mistake and that a better alternative could have been selected. The experience of regret is thought to carry negative utility.

Once this has sunk in here is the study.

Mice learn to avoid regret

Some details about the design of the various restaurants.

Food-restricted mice were trained to encounter serial offers for flavored rewards in 4 “restaurants.” Restaurant flavor and location were fixed and signaled via contextual cues. Each restaurant contained a separate offer zone and wait zone. Tones sounded in the offer zone; fixed tone pitch indicated delay (randomly selected from that block’s offer range) mice would have to wait in the wait zone. Tone pitch descended during delay “countdown” if mice chose to enter the wait zone. Mice could quit the wait zone for the next restaurant during the countdown, terminating the trial.

Being a mouse and going out to eat is not easy.

Taken together, in this task, mice must make serial judgements in a self-paced manner, weighing subjective valuations for different flavors against offer costs and balancing the economic utility of sustaining overall food intake against earning more rewards of a desirable flavor. In doing so, cognitive flexibility and self-control become critical components of decision-making valuation processes in this task, assessed in 2 separate stages of decision conflict (in the offer and wait zones).

At which point the suspense is killing you and you want to read the gist.

Abstract

Regret can be defined as the subjective experience of recognizing that one has made a mistake and that a better alternative could have been selected. The experience of regret is thought to carry negative utility. This typically takes two distinct forms: augmenting immediate postregret valuations to make up for losses, and augmenting long-term changes in decision-making strategies to avoid future instances of regret altogether. While the short-term changes in valuation have been studied in human psychology, economics, neuroscience, and even recently in nonhuman-primate and rodent neurophysiology, the latter long-term process has received far less attention, with no reports of regret avoidance in nonhuman decision-making paradigms. We trained 31 mice in a novel variant of the Restaurant Row economic decision-making task, in which mice make decisions of whether to spend time from a limited budget to achieve food rewards of varying costs (delays). Importantly, we tested mice longitudinally for 70 consecutive days, during which the task provided their only source of food. Thus, decision strategies were interdependent across both trials and days. We separated principal commitment decisions from secondary reevaluation decisions across space and time and found evidence for regret-like behaviors following change-of-mind decisions that corrected prior economically disadvantageous choices. Immediately following change-of-mind events, subsequent decisions appeared to make up for lost effort by altering willingness to wait, decision speed, and pellet consumption speed, consistent with past reports of regret in rodents. As mice were exposed to an increasingly reward-scarce environment, we found they adapted and refined distinct economic decision-making strategies over the course of weeks to maximize reinforcement rate. However, we also found that even without changes in reinforcement rate, mice transitioned from an early strategy rooted in foraging to a strategy rooted in deliberation and planning that prevented future regret-inducing change-of-mind episodes from occurring. These data suggest that mice are learning to avoid future regret, independent of and separate from reinforcement rate maximization.

Author summary

Regret describes a unique postdecision phenomenon in which losses are realized as a fault of one’s own actions. Regret is often hypothesized to have an inherent negative utility, and humans will often incur costs so as to avoid the risk of future regret. However, current models of nonhuman decision-making are based on reward maximization hypotheses. We recently found that rats express regret behaviorally and neurophysiologically on neuroeconomic foraging tasks; however, it remains unknown whether nonhuman animals will change strategies so as to avoid regret, even in the absence of changes in the achieved rate of reinforcement. Here, we provide the first evidence that mice change strategies to avoid future regret, independent of and separate from reinforcement rate maximization. Our data suggest mice accomplish this by shifting from a foraging decision-making strategy that produces change-of-mind decisions after investment mistakes to one rooted in deliberation that learns to plan ahead.