By Emma Young

Let’s say a friend asks you to help them to move house. When deciding how much time you can offer, you might consider how much you’ve helped that particular friend lately (and perhaps how much they’ve helped you). But a new paper in Social Psychology suggests that if that friend is particularly close, you’re likely to have a poorer memory of just how much time you’ve dedicated to helping them. You might offer more help than you would to an acquaintance not just because this friend is closer, but because your brain’s distinction between a close friend and yourself is blurrier.

The idea that the closer we are to someone, the less clear is the distinction between our mental representations of our own self and their self is supported by various earlier studies, including some that we’ve covered. In the new work, Pinar Uğurlar at the University of Cologne, Germany and colleagues asked three separate groups of participants to divvy up a series of theoretical resources (pizzas, for example, and bitcoin) between themselves and another person, then later recall just how much of each they’d given away.

In the first study, the theoretical recipient was the person that the participants had identified as being “closest” to them. These participants had also completed something called the Independent Self-Construal Scale. This asks for levels of endorsement of statements such as “I am a unique person separate from others”. The results showed that those with a more distinct self-representation had better recall of how much pizza, and so on, they had chosen to give away.

In follow-up studies, the team looked for any differences in recall when people were asked to allocate resources to the person closest to them or to someone they had only met once. The researchers found that when people were interacting (in this hypothetical scenario) with a close friend, their recall was significantly poorer than when they were interacting with someone they barely knew.

The hypothetical nature of the studies is certainly a limitation. Also, the team did not directly investigate perceived levels of self/other overlap or the effect of this on memory. Still, the work does suggest that closeness “can indeed impair people’s memory of their own decisions”.

There could be a social upside to this, however. Giving away resources (whether that’s time or food, say, or materials) to benefit others carries an immediate cost to an individual. Blurred distinctions between the self and close others could make it easier for a person to make that selfless decision, and so benefit their group — which in the longer term, benefits them. As the team suggests, “not fully separating the self from others on a purely cognitive level may help groups resolved social dilemmas.”

– Interpersonal closeness impairs decision memory.

Emma Young (@EmmaELYoung) is a staff writer at BPS Research Digest