Human Information Processing Laboratory, School of Social Sciences and Humanities, University of Tampere, Tampere, Finland.
PLoS One. 2011;6(11):e24408. doi: 10.1371/journal.pone.0024408. Epub 2011 Nov 16.
Recent event-related potential studies have shown that the occipitotemporal N170 component--best known for its sensitivity to faces--is also sensitive to perception of human bodies. Considering that in the timescale of evolution clothing is a relatively new invention that hides the bodily features relevant for sexual selection and arousal, we investigated whether the early N170 brain response would be enhanced to nude over clothed bodies. In two experiments, we measured N170 responses to nude bodies, bodies wearing swimsuits, clothed bodies, faces, and control stimuli (cars). We found that the N170 amplitude was larger to opposite and same-sex nude vs. clothed bodies. Moreover, the N170 amplitude increased linearly as the amount of clothing decreased from full clothing via swimsuits to nude bodies. Strikingly, the N170 response to nude bodies was even greater than that to faces, and the N170 amplitude to bodies was independent of whether the face of the bodies was visible or not. All human stimuli evoked greater N170 responses than did the control stimulus. Autonomic measurements and self-evaluations showed that nude bodies were affectively more arousing compared to the other stimulus categories. We conclude that the early visual processing of human bodies is sensitive to the visibility of the sex-related features of human bodies and that the visual processing of other people's nude bodies is enhanced in the brain. This enhancement is likely to reflect affective arousal elicited by nude bodies. Such facilitated visual processing of other people's nude bodies is possibly beneficial in identifying potential mating partners and competitors, and for triggering sexual behavior.
最近的事件相关电位研究表明，枕颞部 N170 成分——以其对面部的敏感性而闻名——也对人体感知敏感。考虑到在进化的时间尺度上，衣服是一种相对较新的发明，它掩盖了与性选择和唤起有关的身体特征，我们研究了早期 N170 大脑反应是否会增强对裸体与 clothed bodies 的反应。在两项实验中，我们测量了 N170 对裸体、泳衣、 clothed bodies、面孔和对照刺激（汽车）的反应。我们发现，与 clothed bodies 相比，裸体的 opposite 和 same-sex 对 N170 振幅的影响更大。此外，N170 振幅随着衣服从全衣、泳衣到裸体的减少而线性增加。引人注目的是，裸体对 N170 的反应甚至大于面孔，而且对裸体的 N170 振幅与裸体的面部是否可见无关。所有人类刺激引起的 N170 反应都大于对照刺激。自主测量和自我评估表明，裸体比其他刺激类别更能引起情感上的唤起。我们得出结论，人体的早期视觉处理对人体与性相关特征的可见性敏感，并且大脑对其他人裸体的视觉处理得到增强。这种增强可能反映了裸体引起的情感唤起。这种对其他人裸体的视觉处理的促进可能有助于识别潜在的交配伴侣和竞争对手，并引发性行为。
