"If the monkey just got a correct answer, a signal lingered in its brain that said 'you did the right thing.' Right after a correct answer, neurons processed information more sharply and effectively, and the monkey was more likely to get the next answer correct as well," Miller said. "But after an error there was no improvement. In other words, only after successes, not failures, did brain processing and the monkeys' behavior improve."
There is apparently an evolutionary basis for why the brain learns that way, Miller said.
"There's a practical reason for it," he said. "Successes are more informative than failures."
If you fail at something you probably know why. You got fired because you showed up late most of the time. Your spouse left because you showed up too many times at the wrong place, with the wrong person. You already know the reason you failed.
"If you succeed, everything has gone right, so there's a lot more information in successes than failures," Miller said. "The brain probably evolved to take advantage of successes because there's more information there."
The research may be an important contribution to our understanding of how we learn, but in this rapidly evolving field, there are still many, many unanswered questions.
Histed noted that scientists still don't understand how the brain works.
"How many neurons store a given memory?" he asked rhetorically. "How does the code work? Do patterns of activity across hundreds or thousands of neurons matter, or can we just study single neurons one by one? I would say most of the questions are unknown."
At the very least, the MIT research challenges an old bromide. Maybe we really don't learn from our mistakes.
And maybe that's why we repeat them, over and over again.