How visual imagery interferes with vision.
Mental visual imagery interferes with vision: the Perky (1910) effect. Is the effect optical, sensory, perceptual, attentional, or just a response bias? Acuity was measured (in undergraduates and graduates) using target lines, with and without images (of lines). Optics (fixation, pupil size, accommodation), response bias, global attention (effort; diversion of attention to imagery), perceptual assimilation (target incorporation by imagery) and perceptual masking (of target by imagery) all fail to explain the effect. Foveally, local attention plays a limited role, as the Perky effect in divided attention is half that in focused attention, but this interaction vanishes with extrafoveal targets. Images produce primarily sensory interference, mimicking a reduction in target energy.
Craver-Lemley
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Northeastern University, Boston, Massachusetts 02115.
Reeves
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D000328:Adult; D001288:Attention; D005260:Female; D006801:Humans; D007092:Imagination; D008297:Male; D010470:Perceptual Masking; D012107:Research Design; D014785:Vision, Ocular; D014796:Visual Perception