Taubert Jessica, Alais David
School of Psychology, The University of Sydney, NSW 2006, Australia.
Vision Res. 2009 Jul;49(14):1877-85. doi: 10.1016/j.visres.2009.04.025. Epub 2009 May 6.
Composite stimuli are whole faces comprised of two halves taken from different individuals. When asked to decide if two identical top halves are the 'same', subjects are more accurate (or faster to respond) in misaligned trials, than in aligned trials. This performance advantage for misaligned trials is referred to as the composite face effect (CFE). The proposed explanation is that aligned features are automatically fused together and form a global identity that interferes with the recognition of smaller components (the composite face illusion, CFI). However, when composite faces are misaligned, it appears to be much easier to ignore the identity of the whole face and process individual features. Here we are interested in why misalignment impairs holistic face perception. In Experiment 1 we tested the difference between horizontal and vertical misalignment and found that holistic interference persists when the vertical distance between features is increased. Is this because vertical misalignment leaves features in the correct vertical arrangement, or because vertically stretched faces are biologically plausible? Experiment 2 tested the difference between these two accounts by measuring the CFE when the two halves of a composite face were separated in stereo-depth and demonstrates that vertical symmetry alone is not sufficient for holistic processing. However, when the faces were slanted through stereo-depth (to an equivalent extent), subjects continued to be inaccurate. Overall, these experiments provide strong evidence that the composite illusion depends on biological plausibility in that the faces must be globally coherent.
复合刺激是由取自不同个体的两半组成的完整面孔。当被要求判断两个相同的上半部分是否“相同”时，与对齐试验相比，受试者在未对齐试验中更准确（或反应更快）。未对齐试验的这种表现优势被称为复合面孔效应（CFE）。提出的解释是，对齐的特征会自动融合在一起并形成一个整体身份，从而干扰对较小组成部分的识别（复合面孔错觉，CFI）。然而，当复合面孔未对齐时，似乎更容易忽略整个面孔的身份并处理各个特征。在这里，我们感兴趣的是为什么未对齐会损害整体面孔感知。在实验1中，我们测试了水平未对齐和垂直未对齐之间的差异，发现当特征之间的垂直距离增加时，整体干扰仍然存在。这是因为垂直未对齐使特征保持正确的垂直排列，还是因为垂直拉伸的面孔在生物学上是合理的？实验2通过测量当复合面孔的两半在立体深度上分开时的CFE来测试这两种情况之间的差异，并表明仅垂直对称不足以进行整体处理。然而，当面孔通过立体深度倾斜（到相同程度）时，受试者仍然不准确。总体而言，这些实验提供了强有力的证据，表明复合错觉取决于生物学上的合理性，即面孔必须在全局上是连贯的。
