On December 20th, 2016 we learned about

Our inclination to share is curtailed by our prefrontal cortex

Every time I tell my three year old that it’s fun to give a good gift, he looks at me like I’m slightly crazy. If he had the dexterity to do it, I’m sure he’d be raising one eyebrow, skeptically wondering if I’m missing the point or if I just misspoke. The weird thing is, while many pro-social behaviors strengthen as we age and develop our frontal cortex, generosity may work in a slightly different way. Scans of brain activity indicate that we have a deep-seated impulse to share, but our prefrontal cortex curbs our generosity.

Arrested altruism

One study looked at how people’s behavior matched up with their brain activity. Test participants were first asked to mimic expressions seen in photos of┬ápeople’s faces, and then just take a look at an image of a hand being pricked with a pin. While working with these visuals, their brains were scanned to see what regions of the brain were activated. The expectation was that areas associated with empathy and recognizing the pain of others would be more active in people who engaged more with each image.

The results of these tests were then compared to a simple donation game, where participants were given money to share potentially share with other people they were told about on the computer. The pattern that emerged was that people who more readily identified with emotion and pain in others also gave more money. People with more activity in the prefrontal cortex, which is associated with impulse control, were less likely to share with others.

To test these patterns more directly, scientists then manipulated the prefrontal cortex to see if it could change people’s behavior. Using a technique called Transcranial Magnetic Stimulation (TMS), researchers were able to temporarily suppress activity in the participants’ prefrontal cortices. With their impulse control reduced, participants were 50 percent more likely to share their money. While the idea of generosity is interesting in this experiment, researchers are more interested in what this demonstrates about social connections in general, and the role the prefontal cortex may play in people that struggle to empathize in general.

Tightfisted toddlers

So how does a three-year-old suddenly have so much impulse control when it comes to giving, but not when say, grabbing at a plate of cookies? It’s certainly not that his prefrontal cortex is fully engaged, since that part of the brain isn’t thought to be fully developed until you’re in your 20s. Instead, his hesitation to give is more likely connected to his exploration of┬áboundaries, self-identity and ownership. The end result to others may look like greed or stinginess, but that’s not what’s motivating his interest in receiving over giving at this point.

Source: Your Giving Brain: Are Humans 'Hardwired' for Generosity? by Mindy Weisberger, Live Science

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