MANIBUS Lab, Psychology Department, University of Turin, Turin, Italy; SAMBA Research Group, University of Turin, Turin, Italy.
MANIBUS Lab, Psychology Department, University of Turin, Turin, Italy.
Neuropsychologia. 2020 Sep;146:107540. doi: 10.1016/j.neuropsychologia.2020.107540. Epub 2020 Jun 25.
Vision and proprioception, informing the system about the body position in space, seem crucial in defining the boundary of the peripersonal space (PPS). What happens to the PPS representation when a conflict between vision and proprioception arises? We capitalize on the Immersive Virtual Reality to dissociate vision and proprioception by presenting the participants' 3D hand image in congruent/incongruent positions with respect to the participants' real hand. To measure the hand-centred PPS, we exploit multisensory integration occurring when visual stimuli are delivered simultaneously with tactile stimuli applied to a body district; i.e., visual enhancement of touch (VET). Participants are instructed to respond to tactile stimuli while ignoring visual stimuli (red LED), which can appear either near to or far from the hand receiving tactile (electrical) stimuli. The results show that, when vision and proprioception are congruent (i.e., real and virtual hand coincide), a space-dependent modulation of the VET effect occurs (with faster responses when visual stimuli are near to than far from the stimulated hand). Contrarily, when vision and proprioception are incongruent (i.e., a discrepancy between real and virtual hand is present), a comparable VET effect is observed when visual stimuli occur near to the real hand and when they occur far from it, but close to the virtual hand. These findings, also confirmed by the independent estimate of a Bayesian Causal Inference model, suggest that, when the visuo-proprioceptive discrepancy makes the coding of the hand position less precise, the hand-centred PPS is enlarged, likely to optimize reactions to external events.
视觉和本体感觉为系统提供关于身体在空间中的位置的信息,对于定义近体空间 (PPS) 的边界似乎至关重要。当视觉和本体感觉之间发生冲突时,PPS 的表示会发生什么变化?我们利用沉浸式虚拟现实技术通过将参与者的 3D 手图像呈现为与参与者真实手一致/不一致的位置来分离视觉和本体感觉。为了测量以手为中心的 PPS,我们利用视觉刺激与施加到手部区域的触觉刺激同时出现时发生的多感觉整合;即视觉增强触觉(VET)。参与者被指示在手受到触觉(电)刺激时忽略视觉刺激(红色 LED),视觉刺激可以出现在手附近或远离手的地方。结果表明,当视觉和本体感觉一致时(即真实手和虚拟手重合),VET 效应会出现空间依赖性调制(当视觉刺激靠近手时比远离手时反应更快)。相反,当视觉和本体感觉不一致时(即真实手和虚拟手之间存在差异),当视觉刺激靠近真实手和远离真实手但靠近虚拟手时,会观察到类似的 VET 效应。这些发现也得到了贝叶斯因果推理模型的独立估计的证实,表明当视知觉差异使得手部位置的编码不太精确时,以手为中心的 PPS 会扩大,可能会优化对外界事件的反应。