Abstract
This special issue appears on the occasion of Emanuel Leeuwenberg’s retirement.
During 40yea rs of research on visual perception, Leeuwenberg studied a wide range
of topics, such as judged complexity, neon effects, subjective contours, visual pattern
completion, ambiguity, assimilation and contrast, temporal order, beauty, object
handedness, veridicality, and visual regularity. To him, the empirical study of these
topics is not a goal in itself but rather a means to focus on underlying principles of
perceptual organization. Most prominently, he advocated the simplicity principle
which states that, from among all possible interpretations of a pattern, the visual system
selects the interpretation with the simplest description.
