There is a biological reason why we learn more from our triumphs than from our failures, according to new research at the Massachusetts Institute of Technology.
The fact that we learn more from our successes than from our failures is not new. Even family pets respond more to reward than punishment, and so do children, according to numerous psychology studies.
But what wasn't known until now is how feedback from the environment guides the learning, according to Earl K. Miller, professor of neuroscience at MIT and senior author of a study in the July 30 issue of the journal Neuron.
Miller and co-authors Mark Histed, now a postdoctoral fellow at Harvard Medical School, and Anitha Pasupathy, now an assistant professor at the University of Washington, reached their conclusions after studying neurological activity on the cellular level in monkeys, which, as we all know, have brains that function very much like ours.
"The main thing that's new here is there have been a lot of studies about how the brain learns, but there is very little understanding about how feedback from the environment guides learning, and that's critical because that's the way we learn," Miller said in a telephone interview. "We learn from the consequences of our actions."
The scientists used monkeys in the research because it isn't possible to monitor individual brain cells, or neurons, without implanting an electrode in the brain, and of course that's out of the question with human subjects. But monkeys can learn things, and then relearn things, fairly quickly, although they are not as good at it as humans.
Miller said the research led to two findings.
"We found that neurons in the prefrontal cortex and the striatum, two brain areas known to be involved in learning, keep track of recent successes and failures for many seconds, long enough for it to play a role in guiding the learning the next time an opportunity to learn comes up," Miller said. "The second thing we found was that the neural processing in the brain improves after a recent success and doesn't improve much after a recent failure. That's quite new. No one has really shown that before."
Histed, lead author of the study, said via e-mail that the research explored the neural circuitry "at the single neutron level."
"We found that the memory of past actions could be maintained by the activity of the neurons," Histed said. "Some neurons started to fire after correct responses, and continued to fire for several seconds until the next action was to be made."
In other words, the neurons themselves retained a memory of the correct action, paving the way for continued success.
The researchers found that monkeys that were rewarded for the right response to a cue learned quickly how to respond the next time they saw the cue, but monkeys that responded incorrectly weren't any better equipped to deal with the same cue the next time they saw it.