Mind games: Our perception of face size is not always correct

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No matter how slim, women and men have often looked at themselves in the mirror and wondered, “Do I look fat?” York University researchers at the Centre for Vision Research say this may be due to their perceptions of body image and not by what they physically see with their eyes.

Laurence Harris

New research out of the Faculty of Health by Sarah D’Amour, supervised by Faculty of Health psychology Professor Laurence Harris, director of York U’s Centre for Vision Research, is the first to provide direct evidence that what we see and think about the shape and size of our face does not necessarily reflect reality. This is the first time that this has been done using psychophysically robust measurements of how accurately healthy participants perceive the size of their face, revealing distortions of the implicit body representation.

In the paper titled, “Perceived face size in healthy adults,” published this week in the journal PLOS ONE, researchers at York U’s Centre for Vision Research discovered that our representation of our face within our brains may not be the same as the face we see in the mirror.

“We have shown that neither healthy males nor healthy females are completely accurate at judging the length and width of their faces, and that accuracy changes depending on the orientation in which the face is viewed,” says Harris. “What we found was that people were not very accurate when they were judging their face in a normal view such as seen in a mirror. People tended to think their faces were wider or fatter than they really were and this was especially true for women. Women had larger errors than men.”

The study sought to explore face perception as a way to reveal how people judge their body dimensions and to gain insight into how body size and shape are processed and represented by the brain. The research findings reveal how accurately people are able to judge their body dimensions and provide insight into how body size and shape are processed and represented by the brain.

In the York U study, 40 participants were asked to complete a body shape questionnaire to assess their level of dissatisfaction with their bodies. They were then shown two life-size photographs; one that offered an accurate reference of their face and the other distorted in the horizontal or vertical dimension. The participants were asked to select the photograph that they perceived to be most like them.

“It’s a very unexpected finding. You would think that something you are used to looking at every day would be something you are very familiar with and that you would be accurate about its perception,” says Harris.  “However what it tells us is that what you see, including what you see in the mirror, is hugely affected not so much by information coming in from the retina, but from your perceptions, from your worldview, or from your memory.”

Study participants were unable to determine which photo best represented their face. The findings were true for both males and females, differing only in the magnitude of their errors. The errors in perception were consistent when the images were viewed both in the upright and upside down orientation. In all cases, face width was overestimated and face length was underestimated. The largest errors were found in the orientations that match our natural face shape, such as when looking in a mirror. Surprisingly, the errors disappeared when the face was viewed tilted by 90 degrees.

“Curiously, the largest errors were found in the most familiar orientations, whereas participants were accurate when the face was viewed in the unfamiliar sideways orientation.”

Previous studies on body size perception have focused on the entire body or particular body parts, such as the belly, thighs or upper arms, all areas of the body with higher concentrations of fat. The studies were aimed at assessing distortions that happen in clinical populations, such as those individuals with eating disorders, and have tended to ignore the role of the face in healthy people’s self-perception. The role of the face is unique because it has internal features and it cannot be viewed directly and requires the use of mirrors. Face perception is a critical aspect of self-awareness.

“What we’re doing here is part of a larger research program where we’re hoping to alter people’s perception of their bodies by giving them various experiences. So if we can develop a way to alter body perception in healthy people, we may be able to alter it in other people, people who have issues with their own body,” says Harris.