I'm sure many of you have heard variations of a saying that indicates the importance of learning from past mistakes. I'm equally sure that most of us have found that easier said than done. A study that was published in yesterday's edition of Science suggests that there is a genetic component to learning from error—depending on our inheritance, some of us will be better at it than others.

The authors of the study introduce things by presenting publications that suggest that the neurotransmitter dopamine is an essential part of recognizing negative outcomes of our actions. They then note that humans happen to have the raw material for a natural experiment: there is a fairly common variant of a dopamine receptor that results in less of the protein being produced. Thus, those with the A2 allele of the dopamine D2 receptor produce less of it, and thus should be less able to respond to dopamine signaling.

The authors then created a "learn-by-doing" test. They showed subjects two Chinese characters from a larger set, and asked them to pick one. The rules were such that when one specific character in the set appeared, choosing it produced a positive outcome. A second character consistently produced a negative one. After the subjects were given a few iterations to try to learn these rules, their ability to apply them was tested.

The dopamine receptor variant seemed to make little difference in recognizing positive outcomes, as the results from the two populations were statistically indistinguishable. There was a significant difference when it came to negative outcomes: those carrying the variant were more likely to keep choosing the symbol that produced bad results. The researchers were able to correlate that with results from functional MRI studies. Areas of the brain that evaluate whether expectations match outcomes were indistinguishable with the symbol associated with positive outcomes, but diverged in tests using the symbol associated with negative ones.

The authors note that this dopamine receptor variant has been associated with addictive disorders and obesity, and suggest that this may result in part from an inability to recognize the negative impact of these behaviors.

Science, 2007. DOI: 10.1126/science.1145044