It was always believed that humans are the only creation of God who possess different kinds of emotions such as happiness, sadness, disappointment, anger and regret. Recently, studies by the professor David Redish of Minnesota expressed that rats are capable of experiencing emotions such as regret.
For proving his research, he has taken a study of food offered to rats. Study was named as restaurant Row. It is such that if you are waiting in a line at the restaurant, if the line is too long you tend to give up and move to some less preferred restaurant. In this case many rats showed a tendency to wait somewhat longer for good food. Many who were deciding to give up also tend to look back.
There is a very fine line between feelings of disappointment and regret. Regret is such an emotion where you realize your mistake and repent for it and you know, what would have been a better option than this. As per Nature Neuroscience paper published, regret is a unique human emotion. A part of brain, orbito-frontal cortex is active in humans when they regret. Same activation of orbito-frontal cortex is observed in rats when they experience, a missed opportunity. How it was derived with rats was allowing rats to choose.
Positively, rats regret for what they should have done and not on the rewards. Research was reviewed by Dr. Mark Walton from Oxford University. He appreciated the methodology and hoped for further development in the process of their thinking and behavior in the wild.