The Type I/Type II Perceptual Dichotomy: A Reanalysis for the Illusions of Extent

Abstract

The categorization of geometrical illusions of extent as Type I or Type II phenomena based on variation in magnitude with age is critically examined. Methodological shortcomings and the failure of contemporary findings to show matching age trends for components of a single illusion are presented as factors undermining the usefulness of this perceptual dichotomy. Finally, it is shown that a new Type I/Type II dichotomy based on changes in perceived size rather than amount of illusion indicates a developmental commonality among most of the illusions of extent.