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Elizabeth Huber, Ione Fine; Measuring lightness induction eight years after human sight-recovery. Journal of Vision 2009;9(14):30. doi: 10.1167/9.14.30.
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Visually normal observers typically seem to rely on a combination of low, mid and high level cues to estimate surface reflectance (perceived as hue or lightness). Here, we examined surface reflectance inference in a subject who lacks higher-level 3D object processing. Sight-recovery subject MM shows typical processing of color and simple 2D form. However, eight years after sight recovery, he cannot recognize 3D shapes depicted in line or shaded drawings, does not infer 3D shape from shading and does not interpret shaded regions in a scene as being shadows. Remarkably, despite no subjective sense of depth or shape, MM is sensitive to a host of lightness illusions containing pictorial depth and shape cues. Relative to control subjects, he shows typical sensitivity to various 3D illusions and heightened sensitivity to simple 2D illusions (e.g., simultaneous contrast). We suggest that an enhanced weighting of local 2D cues (edges, junctions) might underlie MM's performance with more complex scenes, leading to his apparently normal induction in the absence of any explicit interpretation of pictorial depth or shape. (Funded by NEI 61-4892)
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