The ability to infer another person’s state of mind—including his or her perception of you—is an integral component of human interaction. To make business deals, maintain good relationships, and to play a winning hand of poker, we must be able to surmise to some extent what a client, spouse, or friend is thinking. But that skill can go awry in a number of psychiatric disorders, including autism and borderline personality disorder.
Read Montague, a neuroscientist at Baylor College of Medicine, uses a combination of brain imaging and interactive games to explore this skill, with the long-term goal of developing new diagnostic tests for psychiatric disorders.
“This is an extremely promising approach to identifying the mechanisms that underpin these disorders,” says Peter Fonagy, a psychiatrist at University College London who has collaborated with Montague in the past. “Psychiatry is the last medical specialty where the symptoms are equivalent to a diagnosis.”
In a study published today, Montague and collaborators found that people take one of three strategies when playing a simple economics game, and that specific parts of the brain seem to be more active in people who choose to bluff. A second paper published last month shows how the strategies chosen by healthy people playing a similar game change depending on the mental status of their opponent. Researchers ultimately hope to create an automated version of this approach and use it to diagnose disease.
“The capacity that breaks down the most in mental illness is ‘social software,’ such as the ability to pick up signals from people in groups and to collaborate,” says Montague. “We only poorly understand how the brain implements these things, or how it can break.”
Montague and others in the field of neuroeconomics—a relatively young branch of neuroscience that explores how the brain makes decisions—assess how people make choices by asking them to play interactive games. While early studies looked at how factors such as risk and reward contribute to decision-making, more recent research has focused on how people have different approaches to decision making, says Scott Huettel, a neuroscientist at Duke University, who not involved in the research. “You can see that different folks will systematically approach different problems in different ways,” he says.
Better understanding these differences could have a variety of applications. “If you’re trying to sell a product, you don’t want to assume everyone is the same,” says Huettel. “You might want to produce information in different ways based on the idea that people will respond to it differently.” A clearer picture of the spectrum of ways in which healthy people act will also help illuminate how these decision-making skills fall apart in mental illness.
In a paper published today in the journal Proceedings of the National Academy of Sciences, Montague and his collaborators asked people to play a simplified bargaining game. One person, the buyer, is told her own private value of a hypothetical object. The buyer suggests a price to the second player, the seller, who responds by naming a sale price. If the seller’s price is lower than the buyer’s, the trade goes forward. Just like in the real marketplace, the seller wants to charge the highest price but risks losing the sale if the price is too high, while the buyer wants the lowest price. The exchange repeats for a number of sessions, with neither player getting feedback on the outcomes.
Montague and collaborators grouped players according to three broad strategies. “Incrementalists” generally gave the seller a value that was proportional to their private value, suggesting they trusted the other player. “Conservatives” tried to maximize their gains by suggesting mid-range values regardless of the actual value. “Strategists” attempted to deceive the other player, suggesting a value that was inversely related to the given value.
The strategists’ approach required the greatest mentalizing—trying to get into the mind of the other player. To their opponent, their choices resembled those of an incrementalist, suggesting a trustworthy series of suggested prices. But the reality was the opposite; they suggested relatively high prices when the actual value was low, likely stopping that sale. But they surmised that this would increase their credibility in the other rounds of the game; thus, when the private value was high, they could give low suggested prices.
“Bluffing is a specific feature of theory of mind,” explains Montague. “It touches on the capacity to model other people; included in your model of me is your model of my model of you.” He notes that while none of the groups had significant differences in IQ, having an above-average IQ was necessary to be a strategist.