Watching people's brains in real time as they handle a set of decision-making problems can reveal how different each person's strategy can be, according to neuroscientists at the Duke University Medical Center.
"People in our study, like the population at large, differed in the strategies they use to make economic decisions," said Scott Huettel, Ph.D., co-director of the Duke Center for Neuroeconomic Studies and senior author of the study published in Neuron online on May 27. "What sort of strategy people tended to use could be predicted, surprisingly, by how their brain responded to rewards: if there were large responses to monetary reward in a brain area called the ventral striatum, that person tended to simplify decision problems to only consider winning or losing."
"Using studies like this to build a better understanding of how our brains represent our decision strategies may someday allow researchers to use someone's personal traits – say, an adolescent with high impulsivity, but ongoing depression – to predict the decisions that he or she will make," Huettel said. "This could lead to many real-world benefits: designing more effective interventions or creating more useful educational material."
Twenty-three participants were scanned using functional magnetic resonance imaging (fMRI) which reveals real-time changes in brain function as they evaluated complex multi-outcome lotteries. The problems involved real monetary gains and losses – something akin to the universe of factors that someone buying a car must consider, for example. When faced with each problem, the participant chose among ways to improve their lottery chances, such as reducing the worst possible loss.
This study was a collaboration between neuroscientists and decision making experts at the Fuqua School of Business at Duke.
"Our goal was to come up with a risky decision task that would both discriminate between alternative models of choice and represent something that often happens when people allocate scarce resources to make a risky choice more attractive," said John W. Payne, Ph.D., the Joseph J. Ruvane, Jr. Professor of Business. "It was also nice that the task is complex enough to relate to 'real-world' decisions but simple enough to be studied using functional MRI."
The study showed that the brain regions classically associated with "rational" processing, notably the lateral prefrontal cortex, were most active when subjects used a simplifying strategy inconsistent with traditional rational-choice models.
"This result suggests that it was the type of computation that the participants were doing at any given time that activates a brain region, not whether the thought process is rational or irrational," said lead author Vinod Venkatraman, from the Department of Psychology and Neuroscience at Duke.
The finding "argues strongly against the commonly held notion that there are 'rational' and 'irrational' parts of the brain,'" Huettel added.