December 3, 2021

I, Science

The science magazine of Imperial College

Does my bum look big in this? Well, it depends on your perspective, says Julie Gould

The way in which others see you is, more often than not, entirely different from the way you see yourself. Self-perception is largely dependent on your state of mind and how you compare yourself with others. Tabloids and magazines are constantly showing us pictures of others’ bodies, and this can influence how we think about our own.

Let me first retrace my steps. Initially, I wanted to write a story about how to image a phantom limb, inspired by Jo Poole’s article in the Summer 2012 issue of I, Science. I then came across an article in New Scientist about a study carried out by Dr. Matthew Longo of Birkbeck College, London. He had managed to “image” the phantom limb of someone who was born without a left arm.

This struck me as somewhat odd. Surely imaging something requires that something to exist? Armed with questions and curiosity, I went to visit Dr Longo. His technique is not imaging as such; instead, he has come up with a very simple method to map a hand. The hand to be mapped is covered up by a piece of cardboard, and the other is then used to mark the positions of specific landmarks on the hidden hand. A photograph is taken at every stage, and these are superimposed to create a map of the perceived shape of the hand that’s hidden. These maps can then later be compared to the actual shape.

In 2010, Longo published a paper on this method. He used patients with two arms to create the maps. His results showed that we perceive our hands to be a lot shorter and fatter than they actually are. These results mirrored our sense of feeling in the hand – proprioception, the brain’s way of using nervous system input from skin, muscles and joints to locate the body in space.

Our representation of the hand is distorted in several ways. “What my colleagues and I have found is that there is a substantial bias in the two points running across the hand, which is about 40% longer than those running along the hand,” says Longo.

People who have phantom limbs experience a feeling that makes them believe that their missing limb is still there. This year, Longo wanted to see if he could map this phantom hand too. It turns out that if the test subject has a strong enough sense of the phantom hand, this is entirely possible. And the results, published in Psychological Science, were staggeringly similar. The map of the phantom hand, when compared to the mirror image of the test subject’s existing hand, was shorter and squatter.

What this means is that the nature of the distortion comes from our sense of vision. The test subject with a phantom limb did not have a sense of touch in the phantom hand, and so this could not have been the driving force behind the distortion. Neither did they have any memory of having the phantom limb, as they were born without one. The test subject does, however, see their intact arm every day, and is surrounded by those with two arms all the time.

The implications of this work are farther reaching. The fact that we see ourselves as shorter and squatter could contribute to many cases of eating disorders around the world. This technique of mapping the body could help anorexic people begin to see themselves in a different way. Longo predicts that “[anorexics] would map their body as bigger and wider than it actually is”. By showing them the map of how they perceive their own body, and comparing it to the reality, this method could potentially help many people through such disorders.

This brings to mind the experiment done by Gok Wan in his show How to Look Good Naked. Wan asks self-conscious women to stand in front of a line of other women, all increasing in size, and then position themselves at where they believe to be the ‘correct place’ in that line. Nine times out of ten the women place themselves larger than they really are, and Wan ends up shuffling them down towards the slimmer end of the line.

What does this show us? Well, for one, that women (and potentially men) hold a distorted view of themselves, and our visual senses are to blame. This is even the case for those with missing limbs. Maybe this study brings us further insight into the minds of those with eating disorders – until then, we’ll have to rely on Gok Wan to improve our body image, fix our fashion, and make us look good naked.

PNAS 2010: DOI 10.1073/pnas.1003483107
Psychological Science 2012: DOI 10.1177/0956797612441219