in psychology, the relative constancy of the perceived characteristics of an object (its size, shape, color, position) regardless of changes in the conditions of perception (distance, foreshortening, lighting). The problem of constancy, examined long ago by R. Descartes, has still not been worked out sufficiently in its theoretical aspects.

The development of perceptual constancy has been traced in children (E. Brunswik, Austria; J. Piaget, Switzerland) and a relationship has been noted between constancy and objectivity of perception (J. Piaget and others). Also, numerous special relationships describing individual concrete kinds of constancy have been detected (Y. Akishige, Japan).