Supporting this argument, there are several reports in which the properties of stimulus features
surrounding a moving contour drive figure–ground assignment. For example, in “Kinetic Occlusion”, one texture moves laterally, toward, or away from a stationary flanking texture (Gibson, Kaplan, Reynolds, & Wheeler,
1969; Kaplan,
1969). The resulting percept is of a moving surface with an illusory contour, sliding
in front of another stationary surface behind it, that is, occluding (“deleting”) or revealing (“accreting”) the background surface's texture elements. It has been proposed that this effect is due to the accretion or deletion of texture elements, which always signifies that the textured surface is “behind” a moving foreground surface that is occluding it (Gibson et al.,
1969). A related phenomenon is the “Screening Effect” (Michotte, Thines, & Crabbe,
1964) in which a shape (e.g., a white circle) appears on a uniform background (such as a black screen). Over progressive frames, the shape disappears as the uniform background encroaches on it, leading to a perceptual experience of an occluding surface covering the shape. Similar to accretion/deletion of texture, Michotte et al. (
1964) proposed that the disappearing shape is viewed as a permanent static background being occluded by a foreground surface. However, Yonas, Craton, and Thompson (
1987) have argued that both Kinetic Occlusion and the screening effect may instead depend on
grouping between the occluding contour and the adjacent texture elements. They found that Kinetic Occlusion is perceived even when no texture elements are accreted or deleted, as long as there is common motion between the texture elements and a translating boundary. In more recent studies, Palmer and Brooks (
2008) and Palmer, Brooks, and Nelson (
2003) found that similarity between texture elements and a visible moving contour along a number of dimensions (not just common motion) is sufficient to produce a strong figure–ground bias to the contour, a phenomenon they refer to as “Edge-Region Grouping” or ERG (Palmer & Brooks,
2008).