Abstract
In perceptual terms, the human body is a complex 3d shape which has to be interpreted by the observer to judge its attractiveness. Both body mass and shape have been suggested as strong predictors of female attractiveness. Normally body mass and shape co-vary, and it is difficult to differentiate their separate effects. A recent study suggested that altering body mass does not modulate activity in the reward mechanisms of the brain, but shape does. However, using computer generated female body-shaped greyscale images, based on a Principal Component Analysis of female bodies, we were able to construct images which covary with real female body mass (indexed with BMI) and not with body shape (indexed with WHR), and vice versa. Twelve observers (6 male and 6 female) rated these images for attractiveness during an fMRI study. The attractiveness ratings were correlated with changes in BMI and not WHR. Our primary fMRI results demonstrated that in addition to activation in higher visual areas (such as the extrastriate body area), changing BMI also modulated activity in the caudate nucleus, and other parts of the brain reward system. This shows that BMI, not WHR, modulates reward mechanisms in the brain and we infer that this may have important implications for judgements of ideal body size in eating disordered individuals.
Highlights
In perceptual terms, the human body is an evolutionarily important, complex 3D shape
The results show that brain regions responsive to body-shape and size can be modulated by artificially produced body-shaped stimuli with varying BMIPAR
Our behavioural results suggest that BMIPAR is closely correlated with attractiveness judgments and that WHR is not
Summary
The human body is an evolutionarily important, complex 3D shape. It potentially conveys a wide range of information, including information important for human mate selection. When observers judge facial attractiveness functional imaging shows an activation of the medial orbitofrontal cortex, left anterior frontal cortex, left frontal-temporal junction, nucleus accumbens, right caudate nucleus, and visual cortex [6,7,8]. This pattern of activation is likely to reflect the positive reward properties of faces. We hypothesized the attractiveness preferences for bodies would activate the same reward systems
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