Psychological research on perceptual organization is reviewed, and a theoretical framework
is presented to account for it. The review focusses on the organizational phenomena of
shape constancy, motion perception, figural goodness, perceptual grouping, and reference
frame effects. It is argued that the key to understanding them within a unified framework lies
in the concept of local invariance over the group of Euclidean similarity transformations. The
theory offered to account for these phenomena is based on a parallel processing system …