A US-based psychologist, Kip Williams, was strolling through a park when a mis-thrown Frisbee caught him on the back of his head. Unhurt, he picked it up and threw it back to one of the players. They threw it back to him. Briefly he was involved in their game, before the Frisbee players stopped passing it to him and returned to their back-and-forth routine.
A relatively unremarkable social interaction, the scientist was nonetheless surprised at how hurt he felt at being excluded from the game and hurried off to his lab to ascertain what is happening in our brains when we feel left out. He designed a very basic computer animation where two line-drawn figures throw a ball to each other, and occasionally to the player, as represented by a hand in the foreground of the scene. He called the game Cyberball. When playing this game, just like the Frisbee players in the park, the computer will suddenly and unpredictably stop passing the ball to the human player. Cyberball can be played inside a brain scanner, allowing scientists to see exactly what is happening inside our brains when this happens.
It turns out that exclusion hurts. It hurts even though we know it is just an animation, controlled by a motive-less computer. It hurts like a punch in the stomach hurts, activating many of the same brain regions that physical pain turns on. As humans we care deeply about being part of the group.
More and more scientists are starting to explore topics such as empathy, self-control, risk, fairness and guilt from the perspective of neuroscience. Last month we invited two London-based neuroscientists, Iroise Dumontheil and Molly Crockett, to The School of Life to talk about this field in an event on the Social Brain.
Iroise Dumontheil is a cognitive neuroscientist based at Birkbeck University whose work focuses on the adolescent brain. The teenage years are popularly viewed as a time of inner turmoil and this period is indeed characterised by massive changes to the fabric of our brains, particularly those areas that let us empathise with others and control and adapt our thoughts and behaviour to suit each social setting.
It seems the adolescent brain really is wired differently from the adult's. Teenagers use different brain regions to adults when processing social emotions such as guilt; they are more readily influenced by their peers and they do take more risks. Playing a computer-simulated driving game in a psychology department lab, teenagers will be involved in more crashes if they have their friends sitting behind them than when playing alone. Startlingly, brain imaging during the driving game reveals heightened activity in the reward centres of the brain (the orbitofrontal cortex and ventral striatum), showing that risk-taking is more fun when playing with friends.
When adults play the same game, with or without their peers watching, risks are less rewarding and there is much more activity in the prefrontal system which, amongst many other things, is essential for suppressing impulsive behaviour and for future planning.
Meanwhile, our second expert, Dr Molly Crockett, a research fellow at UCL, introduced us to the neuroscience underpinning a subject very close to the heart of many a teenager: deciding what is and isn’t fair.
In a classic brain imaging study, UCLA neuroscientists showed that in a simulated trading game we enjoy receiving a fair price (e.g. a 50:50 split of the loot) more than an unfair price (e.g. a 20:80 split), even if the actual amount of money landing in our hand is exactly the same.
Of course we all like things to be fair. But research from UCL, together with previous work from Stanford, has added an interesting new dimension to this set up. As well as enjoying fair offers, we enjoy (and again the reward signature in our brain activity is clear) punishing people we see acting unfairly, or offering us a bad deal. Revenge is sweet, even when exacting revenge comes at a personal cost, the researchers showed.
In her own work Crockett has delved into which signals in our brains influence our feeling of what is and isn't fair. She has focused on serotonin, one of the brain's chemical key signalling factors, a molecule that has been implicated in diverse social interactions from the swarming of locusts to social play, cooperation and sexual behaviour in mice, monkeys and man.
When Crockett reduced serotonin levels in the brains of her experimental participants and asked them to play the same trading game they were much more likely to punish unfair players by rejecting their offers. And when serotonin levels were raised with drugs called selective serotonin re-uptake inhibitors (Prozac is the best known of these), subjects were less likely to retaliate.
This work has implications outside of the lab. Prolonged stress, poverty and poor diet can deplete the brain of serotonin. Serotonin is a busy molecule in the brain, but following Crockett's work, one important effect of this will be to alter people's decisions about what is fair and to lower their threshold for retaliation. Architects of social policy, take note.
All of this research re-enforces what we intuitively know to be true: we are a social species. We are exquisitely tuned to respond to one another. As a result we can live, work, trade and love within large and functional societies. It also explains why our communities are riven with in-groups and out-groups, why opportunists and criminals exploit the trust and goodwill of others and why our fear of ostracism stops us from taking risks. As more and more neuroscientists start to focus on these topics we must remain hopeful that they will unearth insights into the workings of our social brains that will help us build better personal lives, communities and societies.
Dr Ben Martynoga is a neuroscientist at the National Institute of Medical Research. He hosts our regular special event series 'Grey Matters' in which he talks with key scientists working at the cutting edge of neuroscience, exploring the key advances and what they mean for how we live and make sense of the complex worlds we inhabit. New dates to be announced shortly.