Close friends become absorbed into our self-concept, affecting our ability to distinguish their faces from our own

When we say that our close friends have become a part of us, we're usually talking metaphorically. Yet prior research has shown there is a literal sense in which this is true. For instance, we're slower at judging whether given personality traits apply to us or our friends, compared with when judging whether traits belong to us or someone we're not close to – it's as if our friends' traits and our own have somehow become shared, which makes the judgment trickier. Similarly, in terms of brain activity, we respond to mistakes made by friends in a similar way to how we respond to our own mistakes.

Now a team led by Sarah Ketay at the University Hartford have shown how this absorption of friends into our self-concept can manifest at a visual level, affecting our ability to distinguish their faces from our own. Writing in the Journal of Social and Personal Relationships, Ketay's team said "The present research supports the idea that close others are processed preferentially and may overlap with the self."

An initial study with 24 female undergrads involved them looking at a series of photos of their own face interspersed with photos of a close female friend's face: each time a face appeared on-screen they had to press a button as fast as possible to indicate whether it was their face or their friend's. In another condition, the challenge was similar but this time they had to distinguish between their own face and the face of a gender and race-matched celebrity, such as Reese Witherspoon. All the faces had neutral expressions.

The participants' reaction times were slower in the friend condition than the celebrity condition suggesting they found it more difficult to distinguish their own face from their friend's face, than from a celebrity's face. Further analysis confirmed this wasn't due to any differences in similarity of the friend's/celebrity's faces compared with their own, nor due to any lack of familiarity with the celebrity faces.

A second study with more female undergrads was similar, but this time the researchers used morphing to blend the participants' faces either with the faces of a close female friend or with the face of a gender and race-matched celebrity. Again the challenge was to indicate as fast as possible whether the face on-screen was their own or someone else's. This time the participants were slower to make the self-other judgment when their face was morphed with their friend's than when it was morphed with a celebrity's.

The sample sizes were small (though the study was not underpowered) and exclusively female, so a replication attempt of these findings would certainly be welcome. However, the results are novel: "No previous studies have considered the possibility that … self-other overlap may extend to facial processing," the researchers said.

Further reading

—Seeing you in me: Preliminary evidence for perceptual overlap between self and close others

About the author

Christian Jarrett (@Psych_Writer) is Editor of BPS Research Digest