Stephen Ian D, Sturman Daniel, Stevenson Richard J, Mond Jonathan, Brooks Kevin R
Department of Psychology, Macquarie University, Sydney, Australia.
Perception in Action Research Centre, Macquarie University, Sydney, Australia.
PLoS One. 2018 Jan 31;13(1):e0189855. doi: 10.1371/journal.pone.0189855. eCollection 2018.
Body size misperception-the belief that one is larger or smaller than reality-affects a large and growing segment of the population. Recently, studies have shown that exposure to extreme body stimuli results in a shift in the point of subjective normality, suggesting that visual adaptation may be a mechanism by which body size misperception occurs. Yet, despite being exposed to a similar set of bodies, some individuals within a given geographical area will develop body size misperception and others will not. The reason for these individual difference is currently unknown. One possible explanation stems from the observation that women with lower levels of body satisfaction have been found to pay more attention to images of thin bodies. However, while attention has been shown to enhance visual adaptation effects in low (e.g. rotational and linear motion) and high level stimuli (e.g., facial gender), it is not known whether this effect exists in visual adaptation to body size. Here, we test the hypothesis that there is an indirect effect of body satisfaction on the direction and magnitude of the body fat adaptation effect, mediated via visual attention (i.e., selectively attending to images of thin over fat bodies or vice versa). Significant mediation effects were found in both men and women, suggesting that observers' level of body satisfaction may influence selective visual attention to thin or fat bodies, which in turn influences the magnitude and direction of visual adaptation to body size. This may provide a potential mechanism by which some individuals develop body size misperception-a risk factor for eating disorders, compulsive exercise behaviour and steroid abuse-while others do not.
身体尺寸误判——即认为自己比实际更大或更小——影响着大量且不断增长的人群。最近，研究表明，接触极端身体刺激会导致主观正常点发生偏移，这表明视觉适应可能是身体尺寸误判产生的一种机制。然而，尽管接触的是相似的一组身体，但在给定地理区域内，一些个体仍会出现身体尺寸误判，而另一些则不会。目前尚不清楚这些个体差异的原因。一种可能的解释源于这样的观察结果：身体满意度较低的女性被发现更关注瘦体型的图像。然而，虽然已表明注意力会增强对低水平（如旋转和直线运动）和高水平刺激（如面部性别）的视觉适应效果，但尚不清楚这种效果在对身体尺寸的视觉适应中是否存在。在此，我们检验这样一个假设：身体满意度通过视觉注意力（即选择性地关注瘦体型而非胖体型的图像，反之亦然）介导，对身体脂肪适应效果的方向和程度产生间接影响。在男性和女性中均发现了显著的中介效应，这表明观察者的身体满意度水平可能会影响对瘦体型或胖体型的选择性视觉注意力，进而影响对身体尺寸的视觉适应的程度和方向。这可能为一些个体出现身体尺寸误判（饮食失调、强迫性运动行为和类固醇滥用的一个风险因素）而另一些个体则没有提供一种潜在机制。
