July 30, 2015

A Dartmouth study finds that some people learn faster not because they’re smarter but because they find it more rewarding.

The findings, which appear in the journal NeuroImage, provide the first direct evidence that the dopaminergic neuromodulatory system influences visual learning. Dopamine is a neurotransmitter that helps regulate the brain’s reward and pleasure centers.

Humans often find useful information in conjunctions of visual features, such as color and shape. The ability to quickly and accurately process such conjunctions can be learned, but the neural mechanisms responsible for such learning remain largely unknown. Using neuroimaging, genetic tests and behavioral testing techniques, the Dartmouth researchers found a significant correlation between activity in the caudate nucleus (a part of the dopaminergic system connected to visual areas of the brain) and visual feature conjunction learning rate. Specifically, people who showed a larger difference in activity between positive and negative feedback on an unrelated cognitive task learned visual feature conjunctions more quickly than those who showed a smaller activity difference.

“Basically, you can have two people of identical IQ, but one will get a bigger innate reward signal when they get an answer correct than others, so they’ll tend to learn faster not because they are smarter, but because they find it more rewarding,” says co-author Peter Tse, a professor in Dartmouth’s Department of Psychological and Brain Sciences. “We tend to think that intelligence is the main factor in how well we learn, but it is not the only factor. How rewarding we find learning is also a big factor.”

In a related paper in the journal Cerebral Cortex on individual differences in learning, Tse and his colleagues found that the thicker someone’s cortex is in a brain region known to process motion, the faster they learn a complex motion task.

“Individual differences in learning are pervasive yet mysterious. Why is it that some students remember class material better than others? Why do some animals learn to recognize predators in the environment and survive to propagate their genes, while others do not?” Tse says. “Clearly, such individual differences in learning rate must result from differences in individuals’ brains, but are those neural differences measurable? Using the human visual system as a model, we demonstrate that individual differences in brain anatomy measured using MRI predict individual differences in subsequent learning rate.”

 Professor Peter Tse is available to comment at Peter.U.Tse@dartmouth.edu. PDFs of the two papers are available on request.