The Poggendorff illusion: premeditated or unpremeditated misbehaviour?
Poggendorff illusions have sometimes been explained as arising in a two-stage process, with misalignment consequent upon prior, independently observable misjudgments of angle, extent, or proportion. However, several misalignments combined in one figure can be arranged so that if such prior illusions were the cause, they would have to transform simultaneously in opposed directions to save appearances. When Poggendorff misalignments are deliberately embedded in other illusions, results are intriguingly various, but the comparison of Poggendorff figures with and without associated illusions suggests that the underlying misalignments arise from pre-attentive cues, local to each traverse across a gap.
Phillips
David
D
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D003463:Cues; D006801:Humans; D007600:Judgment; D009903:Optical Illusions; D011601:Psychophysics