Close facial emotions enhance physiological responses and facilitate perceptual discrimination

Accumulating evidence indicates that the peripersonal space (PPS) constitutes a privileged area for efficient processing of proximal stimuli, allowing to flexibly adapt our behavior both to the physical and social environment. Whether and how behavioral and physiological signatures of PPS relate to each other in emotional contexts remains, though, elusive. Here, we addressed this question by having participants to discriminate male from female faces depicting different emotions (happiness, anger or neutral) and presented at different distances (50 cm to 300 cm) while we measured the reaction time and accuracy of their responses, as well as pupillary diameter, heart rate and heart rate variability. Results showed facilitation of participants’ performances (i.e. faster response time) when faces were presented close compared to far from the participants, even when controlling for retinal size across distances. These behavioral effects were accompanied by significant modulation of participants’ physiological indexes when faces were presented in PPS. Interestingly, both PPS representation and physiological signals were affected by features of the seen faces such as the emotional valence, its sex and the participants’ sex, revealing the profound impact of social context onto the autonomic state and behavior within PPS. Together, these findings suggest that both external and internal signals contribute in shaping PPS representation.

越来越多的研究证据表明，个人周边空间（peripersonal space, PPS）是高效加工近距离刺激的优势区域，使我们能够灵活调整行为以适应物理与社会环境。不过，在情绪情境下，个人周边空间的行为与生理特征之间是否存在关联、以及如何关联，这一问题仍未明确。本研究中，我们通过以下方式解答这一问题：让被试对呈现于不同距离（50厘米至300厘米）、带有不同情绪（快乐、愤怒或中性）的男性与女性面孔进行性别辨别任务，同时记录被试的反应时、作答正确率，以及瞳孔直径、心率与心率变异性。研究结果显示，即便控制不同距离下的视网膜成像尺寸，当面孔呈现于被试近距离范围内时，被试的任务表现（即反应时更短）得到了促进。当面孔呈现于个人周边空间内时，上述行为效应同时伴随被试生理指标的显著调控。值得注意的是，个人周边空间表征与生理信号均会受到面孔特征的影响，包括情绪效价、面孔性别以及被试自身性别，这揭示了社会情境对个人周边空间内自主神经状态与行为的深刻影响。综上，本研究结果表明，外部与内部信号共同参与塑造个人周边空间的表征。