Anderson Barton L, Tan Kairen, Marlow Phillip J
University of Sydney, Australia.
University of Sydney, Australia.
Vision Res. 2019 May;158:200-207. doi: 10.1016/j.visres.2019.02.014. Epub 2019 Mar 25.
The mechanisms responsible for generating illusory contours are thought to fulfil an adaptive role in providing estimates of missing contour fragments generated by partial camouflage. One striking apparent counter-example to this view was described in Current Biology 21 (2011) 492-496, which showed that illusory contours could arise in motion displays depicting visible occluding discs occluding and disoccluding thin contours. These motion sequences generate illusory contours even though they play no necessary role in accounting for occlusion and disocclusion of the thin contours. The present work sought to more precisely characterize the quantitative dependence of these 'irrational' contours on the relative contrasts in the image. We show that the perceived strength of the illusory contours generated by these displays depends monotonically on the relative contrast of the occluding and occluded contours and that previous attempts to measure their strength with a method of adjustment appears to be contaminated by response bias. We further show that these illusory contours also arise when the occluding disks are rendered transparent and exhibit similar forms of contrast dependencies. These findings reveal a general methodological problem that can arise using methods of adjustment and provide quantitative data that may be used to identify the neural mechanisms responsible for IC genesis and their perceived strength.
负责产生错觉轮廓的机制被认为在提供由部分伪装产生的缺失轮廓片段的估计方面发挥着适应性作用。《当代生物学》21卷（2011年）492 - 496页描述了一个与该观点明显相悖的例子，该例子表明错觉轮廓可能出现在描绘可见遮挡圆盘遮挡和露出细轮廓的运动显示中。这些运动序列会产生错觉轮廓，尽管它们在解释细轮廓的遮挡和露出方面没有必要作用。本研究旨在更精确地描述这些“不合理”轮廓对图像中相对对比度的定量依赖性。我们表明，这些显示产生的错觉轮廓的感知强度单调依赖于遮挡轮廓和被遮挡轮廓的相对对比度，并且先前用调整法测量其强度的尝试似乎受到了反应偏差的影响。我们进一步表明，当遮挡圆盘变为透明时也会出现这些错觉轮廓，并且呈现出类似的对比度依赖性形式。这些发现揭示了使用调整法可能出现的一个普遍方法问题，并提供了可用于识别负责错觉轮廓产生及其感知强度的神经机制的定量数据。
