Is vision metric? Comment on Lappin and Love (1992).
In a recent paper, Lappin and Love (1992) showed that depth judgments, based on planar motion of a stimulus, are remarkably precise. This led them to the conclusion that perception of planar motion allows acquiring metric information about visual space. We show, however, that Lappin and Love's stimuli contained 2-D cues in the frontal plane that could subserve the subject's judgments. This means that high precision in this task does not necessarily imply metric structure of visual space.
Pizlo
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Purdue University, West Lafayette, Indiana.
Salach-Golyska
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D003867:Depth Perception; D006801:Humans; D010775:Photic Stimulation; D015348:Vision, Binocular