Abstract
Perceptual body size distortions have traditionally been studied using subjective, qualitative measures that assess only one type of body representation–the conscious body image. Previous research on perceived body size has typically focused on measuring distortions of the entire body and has tended to overlook the face. Here, we present a novel psychophysical method for determining perceived body size that taps into implicit body representation. Using a two-alternative forced choice (2AFC), participants were sequentially shown two life-size images of their own face, viewed upright, upside down, or tilted 90°. In one interval, the width or length dimension was varied, while the other interval contained an undistorted image. Participants reported which image most closely matched their own face. An adaptive staircase adjusted the distorted image to hone in on the image that was equally likely to be judged as matching their perceived face as the accurate image. When viewed upright or upside down, face width was overestimated and length underestimated, whereas perception was accurate for the on-side views. These results provide the first psychophysically robust measurements of how accurately healthy participants perceive the size of their face, revealing distortions of the implicit body representation independent of the conscious body image.
Highlights
It is crucial that our brain accurately represents our bodies in almost all situations, especially those involving perception and action
Perceived body size is a fundamental construct that reflects our knowledge of self and is fundamental to all aspects of perception. It relies on mental body representation maps that have been assumed to be accurate in healthy adults
While perceived face size may be correlated with body mass index (BMI) [1], here we reveal errors in people’s perception of their own face, showing that the assumption of an accurate body representation in healthy adults is not correct
Summary
It is crucial that our brain accurately represents our bodies in almost all situations, especially those involving perception and action. It is still not fully understood how we perceive the structure of our bodies or how the body is represented in the brain. Perceived body size is a fundamental construct that reflects our knowledge of self and is fundamental to all aspects of perception. It relies on mental body representation maps that have been assumed to be accurate in healthy adults. While perceived face size may be correlated with body mass index (BMI) [1], here we reveal errors in people’s perception of their own face, showing that the assumption of an accurate body representation in healthy adults is not correct
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