Summary
In contrast with other animals, when the occipital cortex is damaged in man, blindness occurs in spite of intact retinal projections to subcortical centers in the midbrain. By a proper selection of stimuli and responses, however, it can be shown that some information about the visual stimulus may be processed in regions of cortical blindness, even though the stimulus is “not seen”. One striking example of such processing occurs when dark, rather than bright flashes of light are presented in the scotoma. In this case the dark bars may actually be discriminated better in the scotoma than they are in the intact portion of the visual field. The nature of the residual discrimination has the properties of a primitive stereoscopic mechanism that ignores the sign of the stimulus disparity.
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Richards, W. Visual processing in scotomata. Exp Brain Res 17, 333–347 (1973). https://doi.org/10.1007/BF00234098
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DOI: https://doi.org/10.1007/BF00234098