I remember every detail. I was 11. It was summertime and really hot. We’d been outside playing. Along came an ice cream truck, and we clamored around it. I was about to order my favorite flavor but noticed that they had a new one—mint chocolate chip. Hmm, maybe.
Nah. Chocolate, please.
Many years later, I finally tried mint chocolate chip. I loved it. And I was instantly overwhelmed with regret, wishing that I had tried mint chocolate chip back then. All those years of potential enjoyment—irretrievably lost. Ever since, a bitter regret has gnawed at my innards.
Regrets can pile up painfully and cause poor judgment about subsequent choices. All sorts of gurus advise living a life without regret, and I agree. I’m full of regret over the number of things I’ve regretted.
Regret would appear to be a uniquely human state of mind—after all, no other species is capable of the quote attributed to
: “My one regret in life is that I am not someone else.” But not so fast: Researchers have recently discovered that rats also experience something like regret.
How can you study hypothetical rat regret? In a recent paper in Nature Neuroscience,
of the University of Minnesota came up with a wildly clever experimental design.
Rats spent time in an arena with corridors extending from each of its four corners. At the end of three of the corridors was some goody—pieces of cherry, banana or chocolate (there was nothing at the end of the fourth, boring “control” corridor).
The scientists implanted electrodes to monitor activity in the rats’ brains. For each type of food they consumed, the researchers saw a characteristic signature of activity in two parts of the brain (the frontal cortex and ventral striatum) known to play roles in reward and decision-making.
Here’s where choices came in. When a rat entered a corridor, it couldn’t immediately get to the food. The rat would hear a tone, whose pitch indicated how long a wait there would be before the food came down a chute. Then the rat had to decide whether it should stay and wait, or try another corridor, hoping for a shorter delay.
So how to induce putative rat regret? The rat chooses, say, the chocolate corridor and receives a signal indicating a longish wait. It has learned, after a number of trials, to link the tones and the length of wait and to link each corridor with a food. Frustrated, it goes into the banana corridor and…finds out that there’s an even longer wait. Bummer, wrong choice.
What happens after that? The rats look back at the corridors they left behind. Their brains produce the activation profile corresponding to the food they passed up—the chocolate that got away! And the next time they’re in this situation, they’re more likely to stick with whatever corridor they chose first. Rats whose brains were most stimulated by the item left behind showed this tendency most strongly. Thereafter, too, the rats gobbled up their rewards faster.
When the situation was different—for example, equal waits for banana and chocolate—the rats behaved differently. They didn’t look back toward the food they had passed up, and their brains apparently didn’t dwell on it.
The differences between regret and the similar feeling of disappointment are subtle. Disappointment happens when you get less reward than anticipated. Regret involves the same situation—the payoff fails to match your hopes—but occurs when you have a sense that you could have done something about the result. When it comes to choosing corridors for goodies, a rat feels some simple version of being the master of its fate, the captain of its soul—and seems to regret its bad choices.
This is certainly not the first time that another species has turned out to possess the rudiments of a trait that we’ve long considered uniquely human. Still, we can take some consolation in the fact that few rats are likely to regret that their parents let them quit piano lessons way back when.
Scientific Insights From Rats Filled With Regrets – Wall Street Journal
rats – Google News