How a Tiny Brain Region Guides Generosity

Whether and how much we help others may be determined by the brain's basolateral amygdala

- BY TOBIAS KALENSCHER

IMAGINE IT'S SATURDAY MORNING. You're sipping coffee when your best friend texts, “Any chance you could help me move today?” You sigh—there go your weekend plans—but reply, “Of course.” That afternoon you sweat as you carry boxes up a flight of stairs.

A week later a coworker you barely know mentions that she’s moving and could really use a hand. This time you hesitate. You are not as quick to offer help even though the request is nearly identical.

Why does generosity come so naturally for those we are close to but feel more like a burden when the recipient is a stranger or mere acquaintance? Psychologists call this tendency “social discounting”: we are generally more willing to make sacrifices for people to whom we feel emotionally close, and our generosity declines as the social or emotional distance to the potential recipient of help increases.

But what happens in the brain when we make these decisions? And why are some people more generous to socially distant individuals than others are? In recent research, my colleagues and I gained new insight into these questions by examining a rare population of individuals with selective damage to a part of the brain called the basolateral amygdala. Our findings suggest that this small but important structure may be essential for calibrating our generosity based on how close or distant others feel to us.

The amygdala, a small, almond-shaped region nestled deep in the brain’s temporal lobe, is traditionally known for its role in processing emotions, especially fear. But over the past few decades it has become clear that the amygdala, particularly its basolateral part, is a central hub in our social brain.