“Invariants” in Koffka’s Theory of Constancies in Vision: Highlighting Their Logical Structure and Lasting Value

Abstract

SummaryBy introducing the concept of “invariants”, Koffka (1935) endowed perceptual psychology with a flexible theoretical tool, which is suitable for representing vision situations in which a definite part of the stimulus pattern is relevant but not sufficient to determine a corresponding part of the perceived scene. He characterised his “invariance principle” as a principle conclusively breaking free from the “old constancy hypothesis”, which rigidly surmised point-to-point relations between stimulus and perceptual properties. In this paper, we explain the basic terms and assumptions implicit in Koffka’s concept, by representing them in a set-theoretic framework. Then, we highlight various aspects and implications of the concept in terms of answers to six separate questions: forms of invariants, heuristic paths to them, what is invariant in an invariant, roots of conditional indeterminacy, variability vs. indeterminacy, and overcoming of the indeterminacy. Lastly, we illustrate the lasting value and theoretical power of the concept, by showing that Koffka’s insights relating to it do occur in modern perceptual psychology and by highlighting its role in a model of perceptual transparency.

Experimental phenomenology for consciousness.

“…The issue of veridicality in contemporary perception studies is definitely out of place in phenomenology, be it raised in isomorphist or nonisomorphist theories: to be true and evident, appearances have only to obey the principles of organization which guarantee their (phenomenal) invariants (Koffka, 1935; see Burigana & Vicovaro, 2017) and be explained at the same level. For example, the proposed identification between neurophysiological correlates of contours with gradients and contours without gradients, has been criticized by Kanizsa on the basis that situations can be constructed in which it seems that the partial activation of contour discriminators does not give rise to the appearance of margins that continue in the same direction.…”