Perceptual Organization

Abstract

We perceive organized units, objects, rather than mere stimulus elements. Perceptual organization, the grouping of parts into larger units, was emphasized by Gestalt psychology. Rules for how parts of stimuli are grouped together, ‘Gestalt factors,’ such as proximity, similarity, common fate, closure, Einstellung, and past experience were first formulated by Max Wertheimer; they seem to obey a tendency towards Prägnanz, a general tendency of a percept to become structured in the most regular and simple manner possible under the prevailing constraints. This process, understood essentially as self-organization according to the field forces within the nervous system (Köhler), can be demonstrated by multivalent patterns that elicit fluctuating figure-ground differentiation (Rubin) and is nowadays a topic of neural synergetics (Haken and Stadler). Principles of perceptual organization, most thoroughly studied in vision, are cross-modal, i.e., they apply similarly to other sense modalities, e.g., audition. Receptive field organization of neurons can be regarded as a micro-Gestalt (Spillmann and Ehrenstein) affording nonadditive integration of stimulus input. Neurocomputational models (Grossberg) show how perceptual grouping can emerge from interactive activity of cells according to their receptive field properties. Another basic neural correlate of perceptual grouping consists in synchronized coupling of spike activity (Eckhorn).