Imagine you are faced with the classic thought experiment dilemma: You can take a pile of money now or wait and get an even bigger stash of cash later on. Which option do you choose? Your level of self-control, researchers have found, may have to do with a region of the brain that lets us take the perspective of others—including that of our future self.
A study, published today in Science Advances, found that when scientists used noninvasive brain stimulation to disrupt a brain region called the temporoparietal junction (TPJ), people appeared less able to see things from the point of view of their future selves or of another person, and consequently were less likely to share money with others and more inclined to opt for immediate cash instead of waiting for a larger bounty at a later date.
The TPJ, which is located where the temporal and parietal lobes meet, plays an important role in social functioning, particularly in our ability to understand situations from the perspectives of other people. However, according to Alexander Soutschek, an economist at the University of Zurich and lead author on the study, previous research on self-control and delayed gratification has focused instead on the prefrontal brain regions involved in impulse control. “When you have a closer look at the literature, you sometimes find in the neuroimaging data that the TPJ is also active during delay of gratification,” Soutschek says, “but it's never interpreted.”
Soutschek and his colleagues wanted to know more about how the TPJ is involved in social interactions, and also whether it helps us control our own impulses when we are faced with difficult decisions. In their study, subjects underwent 40 seconds of disruptive transcranial magnetic stimulation (TMS)—in which a magnetic coil placed near the skull produced small electric currents in the brain that inhibited activity of the posterior TPJ—then spent 30 minutes completing a task. To rule out a placebo effect, a control group received TMS in a different area of the brain. In one task, subjects made a choice between a reward (ranging between 75 and 155 Swiss francs) for themselves or one that was shared equally between themselves and another person, who ranged from their closest confidante to a stranger on the street. In another task subjects were offered an immediate reward of between zero and 160 Swiss francs or a guarantee of 160 Swiss francs after waiting three to 18 months. In a final task, subjects were instructed to take the perspective of an avatar and indicate the number of red dots on a ball that the avatar would see.
Subjects with an inhibited TPJ were less likely to share the money and were more likely to take the money up front rather than delay gratification and wait for a larger prize. They were also less able take on the perspective of the avatar, which makes sense, says Christian Ruff, a co-author of the paper and an economist at the University of Zurich. “The function of perspective-taking is essential to both of these tasks,” he says, in terms of both “thinking how someone else would feel if you give them money and also how you yourself in the future would feel with that money.”
The findings suggest that the TPJ plays an important role in perspective-taking, which Ruff describes as “a very basic social mechanism” that is essential not only for helping us figure out what other people may be thinking and feeling during social interactions but also in self-control, as we weigh the needs and desires of our current self against the needs and desires of our imagined future self.
Although Soutschek and Ruff emphasize that their study focuses on basic science, they point out it could have important implications for situations where people struggle with self-control, such as in drug addiction. “When people think about addiction, it's often seen as a deficit in impulse control,” Ruff says. “Our results suggest that this other process is also very important—that the afflicted individuals may not be able to take the perspective of their future selves [who have not taken] the drug.”
Ruff adds that in addition to traditional interventions that focus on improving impulse control, it may be worthwhile to explore other approaches that teach people to consider the perspective of their future selves as they attempt to change their behavioral patterns.
Beyond addiction, self-control and our ability to delay gratification is relevant to almost every decision we make in life, from finishing school to exercising regularly to saving for retirement, which is why Ruff considers understanding self-control central to improving health and well-being.
Joseph Kable, a psychologist at the University of Pennsylvania who was not involved in the study, finds the results interesting and surprising. “Most of the research on this brain area which they are inhibiting has suggested that it plays a role in social decisions, in perspective-taking,” Kable says. “I don't think many people would have predicted that it would have a role in temporal dilemmas, where you face this conflict between a smaller immediate reward and a larger reward that you can only get if you wait until the future.”
Kable adds that this research may require us to shift how we think about encouraging people to make more forward-looking choices, because self-control involves “not just inhibiting temptations but actually having the cognitive wherewithal to evaluate the future.”