The persistence of memory: why do we remember faces more than outfits?

Does your crush notice you wearing that same outfit the whole time?

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I am a vain man. When I am late to something, it is usually because I have spent too long in the mirror trying to get my hair to look just right (so that it looks like I haven’t tried). And so, I instinctively think people will notice everything about my outfit, and judge me for wearing the same outfits again and again. And who wants their work-crush to think that their entire wardrobe is three shirts on rotation?

The “spotlight effect” is a psychological phenomenon in which we all believe that we are being noticed by others more than we actually are. One study exploring the matter asked participants to go out in public wearing an “embarrassing” T-shirt. When asked to guess how many people noticed the shirt, they nearly always overestimated.

While this is surely the case when considering perception (and perception of others) alone, the brilliance of memory can often surprise: think of all the random faces that we can remember from years ago. My friends Imi and Hannah, who did not know each other, spent my entire birthday party this year trying to remember where they remembered each other from. They had been at an interview together a few months ago.

But our memory for faces works differently to visual memory in general, notes Dr Rob Jenkins, a reader in psychology at the University of York. Faces change in appearance year to year, of course: but with familiar faces, “we see through these superficial image changes effortlessly”, Jenkins says, whereas with others, a new hair colour can throw us off.

Visual memory in general is a superior form of memory. A series of landmark studies in the late 60s and early 70s tried to determine its limits. Most of these studies consisted of giving subjects thousands of images to study for a few seconds each, and then later giving the subject two pictures, one that was in the initial study phase and one that was brand new. One study found that the subjects had a success rate of picking out the previously studied image 98 per cent of the time.

Jenkins notes that these studies work via recognition rather than recall. Recall is being asked as a witness to describe what the criminal looked like to the forensic artist; recognition is being asked to pick the criminal from a police lineup.

One is far easier than the other.

Recall is, of course, how we notice when Harry from IT wears the same jumper over and over again. Though we’re far more likely to notice it in the first place if it is distinctive: while we might not be able to describe the jumper, we will definitely recognise it.

Jenkins makes the intriguing point, however, that we “don’t know how often we fail to notice the repetition of a jumper”. In other words, perhaps we are overestimating our abilities.

Nora Andermane, a PhD student at the University of Sussex who is studying the neural basis of visual awareness, conducted a more modern version of the image recall study. She wanted to find out if we recalled the gist of an image better than the details of an image.

Images like a duck, a globe and a butterfly were flashed on a screen. Over two and a half hours, a total of 1,500 images were flashed up. Half the participants were tested on their recall a day later; the other half, a week later.

To differentiate between remembering the gist of an image, and the detail of an image, Andermane presented subjects with pairs of images: one was an image they had previously studied, while the other was new. The twist was that, while some pairs were overtly different, such as a ball and a toilet brush, other pairs were more similar, like an image of full cup of tea, and a half cup of tea.

The study found that memories – both gist-like and detail-oriented – deteriorated more after a week. But surprisingly, both types of memories deteriorated at the same rate. Andermane tells me that she thinks this maybe because “losing details from the memory trace may also impair recall of the gist”.

There is also a flip-side when it comes to visual memory and clothing, explains Dr Amy Milton, a lecturer in the department of psychology at Cambridge. “Memory is really about predicting the future. So we use the past to determine what we should expect, and then notice the differences between what we expected and what actually occurred,” she says.

So when someone next compliments you on your new top, thank that person’s visual memory for remembering every other boring outfit you’ve ever worn.

Jason Murugesu is a postgraduate student in science communication at Imperial College London, and a former Wellcome Scholar at the New Statesman.