Susceptibility to the Müller-Lyer Illusion and its Relationship to Differences in Size Constancy

Abstract

The hypothesis that susceptibility to the Müller-Lyer illusion is the result of normal constancy scaling, misapplied, was submitted to direct test. No significant correlations between illusion error and size constancy estimates were obtained. Also invalidated were hypotheses that under-constancy is correlated with non-susceptibility to the illusion, and that over-constancy is correlated with greater illusion error. The results suggest that an approach to the explanation of illusion effects by means of analysing individual differences in size constancy, in intelligence and preferred “perceptual style,” might be fruitful. Some tentative suggestions are made concerning the role of perceptual inference, abstraction and analysing.