How Do We Decide to Leave a Social Interaction?

This post was written by Nikita Mehta, MSc, and Matthew Apps, Ph.D., with edits from Patricia Lockwood, Ph.D., Jo Cutler, Ph.D, and Anthony Gabay, Ph.D.

Ending social interactions can be tricky. How do you decide when to end a phone call with a friend, move on to talk to someone else at a social event, or slowly drift away from a chat with your colleagues? Conversations don’t always end when we want, whether it’s being stuck in a boring discussion or having to end a chat about juicy gossip too soon. But how does our brain decide to end a social interaction to move on to someone else? This is an important question because individuals with symptoms of depression and loneliness are known to experience atypical social interactions, so we need to know how people might make these choices to leave. A recent study examined how people make such decisions, finding that people spend longer with fairer people but also adjust how long they spend with people based on how fair other people are on average in their social environment. Strikingly, this resembles how animals make decisions when foraging for food.

Foraging for food

When an animal is foraging for food, such as collecting berries from bushes, they have to decide when to leave their current location (a “patch”) to move on to find food elsewhere. Typically, when they enter a new patch, there is an abundance of food available. However, as the animal consumes the food, there is less and less left in the patch leading to a choice: When should they leave if they want to get as much as food as possible? To make this choice accurately, the animal must think about how much food they are getting right now in the patch. But also, how likely are they to find another patch that is full of food, and how much of a cost is there to traveling to find another patch? If there are very few patches full of food, or if traveling to find food is hard work, then the best thing to do is stay a bit longer in the current patch.

This strategy will get them more food over time, and it has been shown that many species fit with these predictions. This shows animals are able to evaluate opportunity costs—what is the value of the things they are missing out on. Recently it has been shown that humans in computer-based foraging tasks, behave in very similar ways. As in animals, people’s foraging choices varied based on the opportunity cost and the richness of the environment.

Foraging for fairness in social interactions

Would you spend less time chatting to a stranger at a party if everyone else was also a stranger, or if you knew your friends were on the other side of the room? In answering such questions, we must think about the value of talking to the person we are currently with but also the opportunity costs of seeking out someone else to talk to. Past research has shown that fairness is valued in our social interactions. We will even suffer personal costs if it means stopping other people who are benefitting from behaving unfairly. So maybe we might forage for fairness in our social interactions like animals forage for food?

Gabay et al. (2024) used a new computer game task where participants were paired with virtual social partners in different environments to test that idea. In this task, the partner would share a different pot of credits with the participant every few seconds. The proportion of credits shared by the virtual partners—the fairness—decreased over time, and some partners were more fair than others, sharing more of the money over time. Every five minutes, the participants would move to a different group; it would either be a rich, high-generosity environment (more of the fair partners) or a poor, low-generosity environment (more of the less-fair partners). Crucially, all participants in the study had to do was decide when to leave a partner. When they did, they had to wait eight seconds to be connected to another partner.

The results showed exactly what would be expected based on animal foraging behaviour: People spent less time with unfair partners but more time with all partners in the poor environment. This suggests that people make decisions about how much time to spend with others in a similar way to how animals forage for food.

Leaving decisions differ in loneliness and depression

Previous work showed that individuals with depression or who are lonely spend less time interacting with others, have a lower tolerance of unfair behaviours, have negative evaluations of social partners, and expect them to be unfair. However, there was little evidence for whether such thoughts might influence how much time those with depression and loneliness decide to spend with other people.

Gabay et al. (2024) also assessed participants' depression and loneliness scores using questionnaires and how this related to decisions in the task. The findings showed that in poor social environments, individuals with higher depression and loneliness scores interacted with unfair partners for a lower amount of time compared to in rich social environments. This higher sensitivity to the fairness of the partner in poor environments could have disastrous consequences because when you leave someone but are in an environment where the next person is also likely to treat you unfairly, it could lead to a cycle of never spending time in valuable social interactions.

So how do people leave social interactions? It seems we might forage for fairness. We consider both how fairly we are being treated right now but also how likely it is that our next interaction might be valuable and fair, too. We stay with people longer, even when we are being treated unfairly—in the same way animals stay longer in patches when other places are likely to give them little food. Moreover, atypical decisions for leaving social interactions provide insight into the reasons for having poor social relations and may serve as a potential marker for identifying early symptoms of depression and loneliness.