Newswise — National University of Singapore (NUS), University of California, Berkeley, and University of Illinois at Urbana-Champaign (UIUC) researchers have teamed up to show that when we make strategic decisions in a competitive betting game, at least in the laboratory, genes that modulate dopamine information signaling in the brain partially trigger how we take risks.
In the brain, nerve cells communicate with each other by releasing small signaling molecules that carry information from one cell to the next one. Dopamine is among the brain’s important information carriers and indeed, has been termed the fuel of decision making especially in the brain’s reward network.
NUS Faculty of Arts and Social Sciences researchers, Professor Chew Soo Hong from the Department of Economics and Professor Richard Ebstein from the Department of Psychology, are pioneers in the emerging research direction bringing together biology, psychology and economics. Together with their team including Assistant Professor Zhong Songfa from the NUS Department of Economics, they have carried out some of the first studies showing how dopaminergic genes are involved in risk taking and social and strategic decision making.
“The current study is unique in showing how a set of dopamine genes jointly impact strategic thinking,” said Prof Chew, and “shows how different dopamine genes contribute to how individual thinking differs in a winner-takes-all competitive game.”
“The neurogenetic approach, in stratifying subject’s responses by differences in their genetic variants, is a powerful strategy towards unraveling the neurochemical pathways underpinning human in decision making behaviour,” commented Prof Ebstein.
The study reveals how people have hard wired biases in decision making and strategic thinking that can impact business decisions including those taken at the national and international levels.
The B2ESS (lab for Behavioral x Bioeconomics and the Social Sciences) group at NUS has recruited more than 3,000 Han Chinese students, a population ideal for decision making studies, from both Singapore and Beijing in one of the largest genetic studies of human decision making so far undertaken anywhere in the world. Almost complete genetic information was determined for each of these students. This database has become a treasured resource enabling Prof Chew and Prof Ebstein to undertake scientifically fruitful collaborations at a global level.
The current study was carried out in NUS in collaboration with Assistant Professor Ming Hsu from the Haas School of Business at University of California, Berkeley, and Mr Eric Set, a graduate student from the Department of Economics at UIUC, using 217 subjects from the B2ESS cohort to administer a competitive game that captures individual differences in strategic thinking. The researchers focused on 12 genes, all involved in regulating dopamine.
"If you think of the brain as a computing machine, these are areas that take inputs, crank them through an algorithm, and translate them into behavioral outputs," Asst Prof Hsu said. "What is really interesting about these areas is that both are innervated by neurons that use dopamine."
The competition was a game called patent race, commonly used by economists to study competitive behaviour in a laboratory setting. It involves one person betting, via computer, with an anonymous opponent.
“We know from brain imaging studies that when people compete against one another, they actually engage in two distinct types of learning processes,” Mr Set said. “One type involves learning purely from the consequences of your own actions, called reinforcement learning. The other is a bit more sophisticated, called belief learning, where people try to make a mental model of the other players, in order to anticipate and respond to their actions.”
Using a mathematical model of brain function during competitive social interactions performance was correlated in reinforcement learning and belief learning with different variants or mutations of the 12 dopamine-related genes, and discovered a distinct difference.
It was found that differences in belief learning – the degree to which players were able to anticipate and respond to the actions of others, or to imagine what their competitor is thinking and respond strategically – was associated with variation in three genes which primarily affect dopamine functioning in the medial prefrontal cortex. In contrast, differences in trial-and-error reinforcement learning – how quickly they forget past experiences and how quickly they change strategy – was associated with variation in two genes that primarily affect striatal dopamine. The findings correlate well with Asst Prof Hsu’s previous brain studies showing that the prefrontal cortex is involved in belief learning, while the striatum is involved in reinforcement learning. The high degree of overlap hints at the power of studying decision making at the neural and genetic levels under a single mathematical framework in this emerging direction of research.
The group of researchers from Singapore, Berkeley and University of Illinois at Urbana-Champaign (UIUC) have published their findings on 16 June 2014 in the online early edition of the Proceedings of the National Academy of Sciences.
The research was funded by Singapore’s Ministry of Education, US’ National Institute of Mental Health, and the AXA Research Fund. Other co-authors on the paper are Ignacio Saez of UC Berkeley, Daniel E. Houser of George Mason University, Lusha Zhu of Virginia Tech Carilion Research Institute, and Noah Myung of the US Naval Postgraduate School.