By Emily Reynolds

“You wouldn’t like me when I’m angry”: for the more mild-mannered among us, Bruce Banner’s famous catchphrase may not resonate. But add some hunger — “you wouldn’t like me when I’m hangry” — and many of us can start to relate.

Being hungry, whilst a daily occurrence, can have multiple negative psychological impacts. For one, and most obviously, it simply doesn’t feel good, often leading us to the aforementioned rattiness of “hanger”. But acute hunger has also been linked to an increase in self-interest and a decrease in helping behaviour, too. If your resources are low, the theory goes, you’re much less likely to cooperate with others as you want to keep food for yourself and are unwilling to expend valuable resources like time and energy on helping others.

But this isn’t always the case — at least not according to a new piece of research from Nature Communications . The team argues that acute hunger doesn’t always have an impact on prosociality, even though people strongly believe it does.

Together with their colleagues, Jan Häusser and Christina Stahlecker from Justus-Liebig-University Gießen conducted four studies to examine the phenomenon. In the first, acute hunger was experimentally manipulated, with participants instructed not to eat anything after 10pm the previous night. Those in the control condition were given food before completing tasks, whilst those in the hunger condition were not.

Participants completed the Public Goods Game, a task which sees players deciding whether or not to contribute money to a shared pool. A prosocial response would be the contribution of everything to the shared pot to maximise resources. But those who don’t behave in a prosocial way would also profit, receiving both contributions from the shared pot and their own resources.

But despite the first group’s hunger, they didn’t significantly differ in their contributions compared to the control group. This was even true in a second study, where sessions were scheduled later to make participants even hungrier, and control participants given a higher level of sugar before completing tasks.

In the third and fourth studies, students were recruited in front of a cafe before and after lunch, and had levels of prosociality measured through several tasks. These included a request to participate in a future, follow-up study — for absolutely no financial compensation. And again, the team found that hunger did not predict participants’ levels of prosociality: 45% of hungry participants agreed to volunteer for this future study compared to 47% of sated participants. Another task showed that these participants were also just as willing to share money with a partner as the non-hungry participants.

But despite these findings, our beliefs about what happens when we need food are somewhat different. In an online survey, the team found that people expected hungry people to be more selfish, less helpful and less cooperative. They also believed the same of themselves.

So why the disparity? The team suggests such beliefs are grounded in the “widespread myth of self-interest” — the idea that people are essentially and inherently selfish. If we ascribe to this belief, of course it makes sense that we think people would shed all prosociality when times get tough: underneath the surface, after all, we care about ourselves more than anything.

The findings, as the team points out, only apply to hunger “within the upper boundaries of the natural daily fluctuation typical in Western industrialized societies” — in other words, the results may not be relevant when considering the sort of existential hunger that many experience through poverty, war or natural disasters. The cafe studies also depended on subjective measurements of hunger, making it difficult to tell exactly how hungry participants were and therefore how this may affect their behaviour and choices.

But the idea that people are not inherently selfish — even when going through unpleasant or uncomfortable experiences — may be a valuable takeaway. And as we continue to experience political and environmental turmoil, it may be a lesson we sorely need.

Acute hunger does not always undermine prosociality

Emily Reynolds (@rey_z) is a staff writer at BPS Research Digest