Longo Matthew R, Amoruso Elena, Calzolari Elena, Ben Yehuda Michael, Haggard Patrick, Azañón Elena
Department of Psychological Sciences, Birkbeck, University of London, London, UK.
Neuro-Otology Unit, Division of Brain Sciences, Imperial College London, London, UK.
Atten Percept Psychophys. 2020 Oct;82(7):3636-3647. doi: 10.3758/s13414-020-02079-y.
The distances between pairs of tactile stimuli oriented across the width of the hand dorsum are perceived as about 40% larger than equivalent distances oriented along the hand length. Clear anisotropies of varying magnitudes have been found on different sites on the limbs and less consistently on other parts of the body, with anisotropies on the center of the forehead, but not on the belly. Reported anisotropies on the center of the forehead, however, might reflect an artefact of categorical perception from the face midline, which might be comparable to the expansion of tactile distance perception observed for stimuli presented across joint boundaries. To test whether tactile anisotropy is indeed a general characteristic of the tactile representation of the face, we assessed the perceived distance between pairs of touches on the cheeks and three locations on the forehead: left, right, and center. Consistent with previous results, a clear anisotropy was apparent on the center of the forehead. Importantly, similar anisotropies were also evident on the left and right sides of the forehead and both cheeks. These results provide evidence that anisotropy of perceived tactile distance is not a specific feature of tactile organization at the limbs but it also exists for the face, and further suggest that the spatial distortions found for tactile distances that extend across multiple body parts are not present for stimuli that extend across the body midline.
沿手背宽度方向排列的成对触觉刺激之间的距离，被感知为比沿手长度方向排列的同等距离大约大40%。在四肢的不同部位发现了不同程度的明显各向异性，而在身体其他部位则不太一致，例如在前额中央存在各向异性，但腹部没有。然而，前额中央报告的各向异性可能反映了来自面部中线的分类感知假象，这可能类似于在跨越关节边界呈现的刺激中观察到的触觉距离感知扩展。为了测试触觉各向异性是否确实是面部触觉表征的一个普遍特征，我们评估了脸颊以及前额三个位置（左侧、右侧和中央）上成对触摸之间的感知距离。与先前的结果一致，前额中央明显存在清晰的各向异性。重要的是，前额的左侧和右侧以及双侧脸颊也明显存在类似的各向异性。这些结果提供了证据，表明感知触觉距离的各向异性并非肢体触觉组织的特定特征，在面部也存在，并且进一步表明，对于跨越多个身体部位的触觉距离所发现的空间扭曲，在跨越身体中线的刺激中并不存在。
