Any panhandler will tell you of the importance of staking out the best street corner. But new research suggests that in making the choice to give money to a stranger, the intersection that matters most is one within our brains.
It’s called the right temporoparietal junction (or TPJ for short). Along with many other crucial functions, this neural crossroads gives us the ability to understand the perspectives of others—a prerequisite for empathy.
Swiss scholars report they have found a strong connection between the TPJ and a person’s willingness to engage in selfless acts.
“The structure of the TPJ strongly predicts an individual’s set point for altruistic behavior, while activity in this brain region predicts an individual’s acceptable cost for altruistic actions,” reports lead author Yosuke Morishima of the Laboratory for Social and Neural Systems Research at the University of Zurich’s Department of Economics.
Writing in the journal Neuron, Morishima and his colleagues describe an experiment in which 30 “normal, healthy adults” played a series of games while their brains were being scanned. The researchers measured the size of each person’s TPJ, as well as fluctuations in its level of activity, during the course of the experiment.
“In each trial,” they note, “subjects faced a binary choice in which they would increase or decrease their partner’s monetary payoff.” The cost to the participant of helping their partner (who was anonymous) varied from trial to trial.
In their key finding, the researchers found a strong association between altruistic behavior and the volume of gray matter in a person’s TPJ. (Gray matter refers to the darker tissue of the brain, which consists mainly of nerve cell bodies.) In short, those with bulkier TPJs were more willing to do nice things for strangers.
This region of the brain was most intensely active when the participants faced tough decisions—that is, during trials when they could choose to act altruistically, but only at a high price to themselves. This provided further evidence that the TPJ plays a key role in how such decisions get made.
These findings “provide a plausible biological account of the stability of altruistic preferences,” the researchers write. Big-time philanthropists like Bill Gates probably have robust TPJs; your miserly Uncle Fred, not so much.
As senior study author Ernst Fehr noted in an e-mail exchange, a tendency toward altruistic behavior most likely develops “through appropriate training or social practices” during childhood or adolescence. That’s the period when the brain is rapidly developing, and the volume of one’s TPJ is still in flux.
That said, Fehr added that the brain “keeps some plasticity and can also be shaped as an adult.” This suggests we are not complete prisoners of our neurobiology.
So can someone who wants to be a more altruistic person do so by consciously overriding one’s self-oriented impulses? Can we re-train this part of the brain?
“It has not yet been proved,” Fehr replied, “but my conjecture is that it is not impossible.”
