Lecture

The simplicity principle in visual perception

Peter A. van der Helm

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Abstract. The perceptual counterpart of the mathematical MDL principle, i.e. the simplicity principle, states that the human visual system selects the simplest interpretation of a given visual stimulus. This perceptual principle has a longer research history than its mathematical counterpart but, due to its informal formulation, had to rely mainly on empirical evidence. Such evidence is necessary but not sufficient and has to be complemented with formal theoretical evidence. Perception research already attacked successfully the problems of defining regularity (rather than of defining randomness, as in mathematics), of complexity measurement, and of computability. Yet, theoretically, the veridicality (or predictive power) of the perceptual simplicity principle remained unclear. In this context, mathematical research on the MDL principle has been extremely helpful, by providing the perceptual simplicity principle with a firm formal foundation. Furthermore, it provides a better conceptual framework for theoretical and empirical research into, for instance, the status of perceptual categories, and the relation between viewpoint dependencies and viewpoint independencies in object perception.

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