Reconciling simplicity and likelihood principles in perceptual organization.
Nick Chater · Psychological Review · 1996
Two principles of perceptual organization have been proposed.The likelihood principle, following H. L. E yon Helmholtz ( 1910Helmholtz ( / 1962 ) ), proposes that perceptual organization is chosen to correspond to the most likely distal layout.The simplicity principle, following Gestalt psychology, suggests that perceptual organization is chosen to be as simple as possible.The debate between these two views has been a central topic in the study of perceptual organization.Drawing on mathematical results in A. N. Kolmogorov's ( 1965 ) complexity theory, the author argues that simplicity and likelihood are not in competition, but are identical.Various implications for the theory of perceptual organization and psychology more generally are outlined.How does the perceptual system derive a complex and structured description of the perceptual world from patterns of activity at the sensory receptors?Two apparently competing theories of perceptual organization have been influential.The first, initiated by Helmholtz ( 1910Helmholtz ( /1962)), advocates the likelihood principle: Sensory input will be organized into the most probable distal object or event consistent with that input.The second, initiated by Wertheimer and developed by other Gestalt psychologists, advocates what Pomerantz and Kubovy (1986) called the simplicity principle: The perceptual system is viewed as finding the simplest, rather than the most likely, perceptual organization consistent with the sensory input '.There has been considerable theoretical and empirical controversy concerning whether likelihood or simplicity is the governing principle of perceptual organization (e.g., Hatfield, & Epstein, 1985;Leeuwenberg & Boselie, 1988;Pomerantz and Kubovy, 1986;Rock, 1983).The controversy has been difficult to settle because neither of the key principles, likelihood and simplicity, is clearly defined.Moreover, there have been suspicions that the two principles are not in fact separate, but are two sides of the same coin.Pomerantz and Kubovy ( 1986 ) cited Mach (1906/1959)--"The visual sense acts therefore in conformity with the principle of economy [i.e., simplicity], and at the same time, in conformity with the principle of probability [i.e., likelihood]" (p.215)--and themselves have suggested that some resolution between the two approaches might be possible.Moreover, the close mathematical relationship between simplicity and likelihood has been widely acknowledged in a range of technical literatures, in computational modeling of perception (e.g.