In humans, regret is a common occurrence in everyday life and comes in many shapes and forms. For instance, a person might regret not asking out their crush or not waking up on time for a dream job interview. Where is regret expressed, and are humans the only species to experience the sensation of regret? The answer to this question is no, as shown in the very informative and educational talk by speaker Brian Sweis as well as the article titled "You Won't Regret Reading This", written by Steiner and Redish. In this article and experiment, they demonstrate that "neural signals related to regret are encoded in OFC and ventral striatum in rats performing an economic decision task". In both humans and rats, the sensation of regret is expressed in a region of the brain called the Orbitofrontal Cortex. In an experiment called "The Restaurant Row Task", rats were placed inside a maze and trained to circle past a series of four possible reward zones, each with a different food item that remains constant throughout the entire experiment. Once inside each reward zone, a particular tone would be played for the rat, the pitch of which informed the rat of how long it would have to wait for the reward (food). In this experiment, by randomly varying the delay and pitch, Steiner and Redish determined the amount of time that rats were willing to wait for each different food item. The rats experienced a cost-benefit analysis at each zone to see if they wanted to wait for food or decided to move onto the next food item. In some scenarios, the rats skipped a good delay-reward pairing only to discover that the next zone had a much longer wait for a food that the rat did not like as much. In this scenario, the rat was seen to show signs of regret such as turning their head back to the other zone that they passed up. Researchers measured brain activity of the rats by examining neural encoding in the OFC and the ventral striatum at the exact moment of perceived "regret". They discovered that the rats were "thinking about the choice that they could have made if they had stayed at the previous zone". The data suggested the the OFC activity when the rats looked back was the same as the activity shown when the rats had previously considered the particular reward zone. This entire regret process in the Orbitofrontal Cortex allows for the animal to process the rewards that might have been and accommodate for the mistakes made in future decisions in order to maximize rewards received.
A similar article describing regret in rats was written on "Science News", and it is titled "Study Reveals Rats Show Regret, a Cognitive Behavior Once Thought to be Uniquely Human". This article describes the above study that was performed by Redish and how each rat was presented with a series of food options but only limited time at each "restaurant". The results stated that "rats were willing to wait longer for certain flavors, implying that they had individual preferences". When a rat dismissed a good deal for a less satisfactory one, they were shown expressing regret. In explaining the results of his study, Redish commented on human as well as rat regret, stating that "you don't regret the thing you didn't get, you regret the thing you didn't do". In humans, this regret could be failing to study for an important college exam. In rats, the regret is clearly shown with missed food opportunities.
This study can be expanded to apply to humans and the understanding of why humans do the things they do. Redish states that by examining regret patterns in animals, the reasoning of how regret affects human decisions may one day be uncovered.
Sources:
http://esciencenews.com/articles/2014/06/09/study.reveals.rats.show.regret.a.cognitive.behavior.once.thought.be.uniquely.human
https://luc.app.box.com/neuroscienceseminar/1/5783478297/47239559561/1
https://www.google.com/search?q=restaurant+row+rats&safe=strict&biw=1366&bih=643&source=lnms&tbm=isch&sa=X&ved=0ahUKEwit9L61l6bLAhUivIMKHdR6CYwQ_AUIBygC#imgrc=2F4jP_HIc-l4QM%3A
Bissonette, B., Gregory, Bryden, W., Daniel, Roesch, R., Matthew.
"You Won't Regret Reading This" Nature Neuroscience
Redish, David.
"Study reveals rats show regret, a cognitive behavior once thought to be uniquely human" Science News
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