Erlikhman Gennady, Singh Gurjyot, Ghose Tandra, Liu Zili
Department of Psychology, University of California, Los Angeles, United States.
Department of Psychology, Technical University of Kaiserslautern, Germany.
Vision Res. 2019 May;158:126-134. doi: 10.1016/j.visres.2019.02.001. Epub 2019 Mar 7.
The tilt aftereffect (TAE) occurs when, after adapting to an oriented line, a vertical line appears to be tilted in the opposite direction. The magnitude of the TAE has been shown to relate to the salience of the adapting stimulus (e.g., its contrast) as well as to the similarity between the adapting and testing stimuli. However, the relationship between TAE and orientation uncertainty - variability in the perceived orientation of the stimulus - of either the adapting or the testing stimulus and, more importantly, change in orientation uncertainty as a function of adaptation have not previously been explored. We manipulated stimulus salience by using a variety of contour types, including real and illusory contours. Tilt aftereffects were observed even for stimuli that had much weaker or invisible illusory contours. Orientation uncertainty of the adapting stimulus, as measured by the slope of a psychometric function in orientation discrimination, was positively correlated with TAE magnitude for real and illusory contours, but not for stimuli with weak contour percepts. On an individual subject level, orientation uncertainty increased post-adaptation and was correlated with pre-adaptation uncertainty. That is, individuals with more variability in their perception of orientation before adaptation showed increased variability in orientation discrimination following adaptation. This may account for some of the variability in TAE across individuals and stimulus types and is consistent with previous findings on increased orientation discrimination thresholds post-adaptation for nearby orientations.
倾斜后效（TAE）是指在适应一条定向线之后，垂直线看起来会向相反方向倾斜的现象。研究表明，TAE的大小与适应刺激的显著性（如对比度）以及适应刺激和测试刺激之间的相似性有关。然而，此前尚未探讨过TAE与适应刺激或测试刺激的方向不确定性（即刺激感知方向的可变性）之间的关系，更重要的是，也未探讨过作为适应函数的方向不确定性的变化。我们通过使用各种轮廓类型（包括真实轮廓和虚幻轮廓）来操纵刺激的显著性。即使对于具有非常微弱或不可见虚幻轮廓的刺激，也观察到了倾斜后效。通过方向辨别心理测量函数的斜率来衡量，适应刺激的方向不确定性与真实轮廓和虚幻轮廓的TAE大小呈正相关，但对于轮廓感知较弱的刺激则不然。在个体水平上，适应后方向不确定性增加，并且与适应前的不确定性相关。也就是说，在适应前方向感知变化较大的个体，在适应后方向辨别变化也会增加。这可能解释了不同个体和刺激类型之间TAE的一些变化，并且与之前关于适应后附近方向的方向辨别阈值增加的研究结果一致。
