DFG Research Unit Person Perception, Friedrich-Schiller-University of Jena, Jena, Germany ; Institute of Psychology, University of Regensburg, Regensburg, Germany.
PLoS One. 2013 Aug 21;8(8):e70525. doi: 10.1371/journal.pone.0070525. eCollection 2013.
Adaptation-related aftereffects (AEs) show how face perception can be altered by recent perceptual experiences. Along with contrastive behavioural biases, modulations of the early event-related potentials (ERPs) were typically reported on categorical levels. Nevertheless, the role of the adaptor stimulus per se for face identity-specific AEs is not completely understood and was therefore investigated in the present study. Participants were adapted to faces (S1s) varying systematically on a morphing continuum between pairs of famous identities (identities A and B), or to Fourier phase-randomized faces, and had to match the subsequently presented ambiguous faces (S2s; 50/50% identity A/B) to one of the respective original faces. We found that S1s identical with or near to the original identities led to strong contrastive biases with more identity B responses following A adaptation and vice versa. In addition, the closer S1s were to the 50/50% S2 on the morphing continuum, the smaller the magnitude of the AE was. The relation between S1s and AE was, however, not linear. Additionally, stronger AEs were accompanied by faster reaction times. Analyses of the simultaneously recorded ERPs revealed categorical adaptation effects starting at 100 ms post-stimulus onset, that were most pronounced at around 125-240 ms for occipito-temporal sites over both hemispheres. S1-specific amplitude modulations were found at around 300-400 ms. Response-specific analyses of ERPs showed reduced voltages starting at around 125 ms when the S1 biased perception in a contrastive way as compared to when it did not. Our results suggest that face identity AEs do not only depend on physical differences between S1 and S2, but also on perceptual factors, such as the ambiguity of S1. Furthermore, short-term plasticity of face identity processing might work in parallel to object-category processing, and is reflected in the first 400 ms of the ERP.
适应相关的后效 (AEs) 表明，面部感知可以通过最近的感知经验改变。除了对比行为偏见之外，早期事件相关电位 (ERPs) 的调制通常在分类水平上报告。然而，适应刺激本身对面部身份特定的 AEs 的作用尚不完全清楚，因此本研究对此进行了调查。参与者适应了在一对著名身份 (身份 A 和 B) 之间系统变化的形态连续体上的人脸 (S1)，或者适应了傅里叶相位随机化的人脸，然后必须将随后呈现的模糊人脸 (S2; 50/50%A/B) 匹配到相应的原始人脸之一。我们发现，与原始身份相同或相近的 S1 导致强烈的对比偏见，A 适应后更倾向于身份 B 的反应，反之亦然。此外，S1 越接近形态连续体上的 50/50%S2，AE 的幅度就越小。然而，S1 与 AE 之间的关系并非线性关系。此外，更强的 AE 伴随着更快的反应时间。同时记录的 ERPs 分析显示，刺激后 100 毫秒开始出现分类适应效应，在大约 125-240 毫秒时，双侧半球的枕颞部位最为明显。大约在 300-400 毫秒时发现了 S1 特异性的幅度调制。当 S1 以对比的方式影响感知时，ERP 的反应特异性分析显示从大约 125 毫秒开始，电压降低。当 S1 没有以对比的方式影响感知时，电压不会降低。我们的结果表明，面部身份 AE 不仅取决于 S1 和 S2 之间的物理差异，还取决于感知因素，例如 S1 的模糊性。此外，面部身份处理的短期可塑性可能与物体类别处理并行运作，并反映在 ERP 的前 400 毫秒。
