School of Optometry and Vision Science, University of Bradford, UK.
School of Optometry and Vision Science, University of Bradford, UK; Department of Vision Sciences, Glasgow Caledonian University, UK.
Vision Res. 2019 Dec;165:1-12. doi: 10.1016/j.visres.2019.09.006. Epub 2019 Oct 11.
Although faces can be recognized from different viewpoints, variations in viewpoint impair face identification ability. The present study quantified the effect of changes in viewpoint on sensitivity to face identity. We measured discrimination thresholds for synthetic faces presented from several viewpoints (same viewpoint condition) and the same faces shown with a change in viewpoint (5°, 10° or 20°) between viewing and test. We investigated three types of viewpoint change: (i) front-to-side (front-view matched to 20° side-view), (ii) side-to-front (20° side-view matched to front) and (iii) symmetrical (10° left to 10° right). In the same viewpoint condition, discrimination thresholds were lowest for faces presented from 0° and increased linearly as the viewing angle was increased (threshold elevations: 0° = 1.00×, 5° = 1.11×, 10° = 1.22×, 20° = 1.69×). Changes in viewpoint between viewing and test led to further reductions in discrimination sensitivity, which depended upon the magnitude of viewpoint change (5 = 1.38×, 10 = 1.75×, 20 = 2.07×). Sensitivity also depended upon the type of viewpoint change: while a 20° front-to-side viewpoint change increased discrimination thresholds by a factor of 2.09×, a symmetrical change in viewpoint, of the same magnitude, did not significantly reduce sensitivity (1.26×). Sensitivity to face identity is significantly reduced by changes in viewpoint. Factors which determine the extent of this reduction include the magnitude of viewpoint change and symmetry. Our results support the premise of viewpoint-dependent encoding of unfamiliar face identities, and suggest that symmetry may be used to recognize identities across different viewpoints.
尽管人脸可以从不同的视角进行识别，但视角的变化会损害人脸识别能力。本研究定量评估了视角变化对面部身份识别敏感性的影响。我们测量了从几个视角（相同视角条件）呈现的合成人脸的辨别阈值，以及在观看和测试之间视角变化（5°、10°或 20°）下相同人脸的辨别阈值。我们研究了三种类型的视角变化：（i）从前到侧（正面视图与 20°侧面视图匹配），（ii）从侧到前（20°侧面视图与正面匹配）和（iii）对称（10°左到 10°右）。在相同视角条件下，从 0°呈现的人脸的辨别阈值最低，并且随着视角的增加呈线性增加（阈值升高：0°=1.00×，5°=1.11×，10°=1.22×，20°=1.69×）。观看和测试之间的视角变化导致辨别敏感性进一步降低，这取决于视角变化的幅度（5°=1.38×，10°=1.75×，20°=2.07×）。敏感性还取决于视角变化的类型：虽然 20°的从前到侧视角变化将辨别阈值增加了 2.09×，但相同幅度的对称视角变化不会显著降低敏感性（1.26×）。身份识别的敏感性会因视角变化而显著降低。决定这种降低程度的因素包括视角变化的幅度和对称性。我们的结果支持了不熟悉的面部身份编码依赖于视角的前提，并表明对称性可用于识别不同视角下的身份。
