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Organization in vision essays on gestalt perception

Factors that influence figure assignment Figure 2: Classical organization in vision essays on gestalt perception cues Regions that are convex, symmetric, smaller in area, enclosed, or surrounded are more likely to be seen as figure than contiguous regions that are concave, asymmetric, larger in organization in vision essays on gestalt perception, or surrounding.

In Figure 2 a, the black regions have convex parts, whereas the white regions have concave parts. In Figure 2 b, the black regions are smaller in area than the white regions. In Figure 2 c, the black regions are symmetric around a vertical axis, whereas the white regions are asymmetric.

And, in Figure 2 d, the black region is enclosed and surrounded by the white region. In displays like these, observers are more likely to perceive the black regions as the shaped figures, and to perceive the white regions as backgrounds. Note that if the white, rather than the black, regions were convex, symmetric, smaller, or enclosed they would be seen as figures; these effects do not depend upon the contrast polarity of the regions relative to the overall background.

Thus, when testing the effectiveness of potential configural cues, it is important for contiguous regions to have equal contrast with the overall background. We have achieved this by using black and white regions on a medium gray overall background in Figure 2 a - Figure 2 d. The importance of these classic configural properties for figure-ground perception was originally revealed via demonstrations e.

Empirical studies have tended to support those demonstrations e. For instance, experiments assessing the effectiveness of symmetry as a configural cue have produced equivocal results e. The classical configural cues were all properties that could be measured on the image; they were geometric in that they were properties of the simple rectilinear or curvilinear lines or shapes in the displays. In support of this claim, They showed that novel regions possessing the configural properties were seen as figures see Figure 1 and Figure 2 d, for instance.

Evidence that figure-ground perception can proceed without input from past experience for novel shapes does not eliminate the possibility that past experience also exerts an influence when shapes are familiar, however.

They demonstrated widespread use of the classical configural cues by adults, at organization in vision essays on gestalt perception when displays were exposed for long durations. Such findings cannot demonstrate innateness, however, because high agreement between adults can arise because of learning. Thus, it is unclear whether responses to these configural properties per se are innate, or whether a sophisticated learning mechanism has evolved that allows organization in vision essays on gestalt perception to extract the statistical properties of the environment in which they live and configural cues are among organization in vision essays on gestalt perception properties.

Non-classical geometric configural properties Figure 3: Standing woman depicted in black on the left. An Assumption in Peril. Recent experiments tested directly whether or not past experience could affect figure assignment, and found that it could, contrary to the Gestalt claim e.

In the displays used in these experiments a portion of a familiar, nameable, object was suggested on only one side of an edge; hence, the shapes potentially perceived on opposite sides of the edge differed in familiarity. Observers are more likely to perceive the figure on the side of the edge where the familiar object lies when the display is presented with the familiar object in its typical upright orientation see Figure 3 a rather than in an inverted orientation see Figure 3 b.

For review see Peterson Orientation dependency was critical for attributing these effects to past experience rather than simply to geometric properties because the former but not the latter would vary with a change organization in vision essays on gestalt perception upright to inverted.

Experiments also showed that effects of familiarity were observed only when the parts of the familiar object were shown in their proper spatial relationships e. Effects of familiarity were not observed when the parts were rearranged e. These effects necessarily depend upon past experience and as such may seem organization in vision essays on gestalt perception differ from effects attributable to the classical configural cues because past experience is not always instantiated as geometric relationships, whereas the configural cues are.

However, we note that in the experiments we have organization in vision essays on gestalt perception, past experience is operationalized as a familiar configuration of parts which can be specified geometrically. It may not be the case that all forms of past experience influence figure assignment but only those that are embodied geometrically.

Peterson and Gibson showed that familiar configuration can affect figure assignment even when it conflicts with classic Gestalt configural cues. Consider displays like Figure 3 d, where the asymmetric black region portrays a familiar object a seahorse whereas the symmetric white region portrays a novel shape. Here, the cues of familiar configuration and symmetry compete with each other. When an upright version of this display is exposed briefly, familiar configuration is slightly more powerful than symmetry, but the two cues seem to compete so that the shaped figure is sometimes seen on the unfamiliar symmetric white side of the central edge.

These results organization in vision essays on gestalt perception that familiar configuration does not invariably dominate other cues. Instead, it is one of many visual properties used for figure assignment Peterson The base of the black region is wider than the contiguous white region.

The black region on the left protrudes into the white region. Modern psychologists have identified other geometric properties that determine which regions of the visual field will be seen as figures. The lower of two regions separated by a horizontal border is more likely than the upper region to be seen as the figure see Figure 4 b; Vecera et al.

The configural cues are shape cues; they determine where the shape lies with respect to an edge. But recall that the region complementary to the figure is often perceived to complete behind it. The perceptual completion of the ground has not received much attention in the study of figure-ground perception. It is possible that at least some of the configural properties may convey depth information as well as shape information Burge et al.

Depth cues The region that appears shaped also tends to appear closer although this relationship does not always hold, e. Depth cues determine which of two contiguous regions is closer to the viewer even in the absence of the classic configural cues.

Closer regions tend to be shaped by the edges they share with contiguous regions in the visual input, and the latter typically appear to continue behind as backgrounds. There are ample empirical investigations of the depth cues: Such research is needed for a full understanding of figure-ground perception. Organization in vision essays on gestalt perception factors Subjective factors Subjective factors can also influence figure assignment.

Subjective factors can alter the likelihood of seeing the figure on one side of an edge, but typically they tend not to overpower configural cues. Spatial frequency Figure 5: High spatial frequency pattern fills every other region, with low spatial frequency patterns in intervening regions.

Reprinted with permission from Journal of Experimental Psychology: Human Perception and Performance: Extremal edges An extremal edge EE is a self-occluding edge. A sample is shown in Figure 5 b, where the extremal edge lies on the left side of the central border. Research is needed to determine whether extremal edges are depth cues, figural cues, or both. Watercolor Illusion Consider a region bounded by two thin colored lines that are parallel organization in vision essays on gestalt perception and touching each other.

One of the colored lines contrasts less with the background than the other.

Not much is known about the Watercolor Illusion as a figural cue; unlike other figural cues, organization in vision essays on gestalt perception has not been examined in isolation, it has always interacted with one or more of the other figural cues. Ambiguous figure-ground perception Figure 6: Figure-ground perception can be ambiguous. In this display, viewers can perceive either the central white region or the surrounding black region as the figure at any moment.

When the white region appears to be the figure, it has a definite shape, one that resembles a white vase or a goblet. The factors that favor seeing the white region as figure include partial symmetry, small area, closure, and enclosure.

Organization in vision : essays on gestalt perception

When the outer black regions appear to be the figures, they have definite shapes, ones that resemble two profiles of people facing each other. The factor of familiarity favors perceiving the black regions as figures. Global symmetry of the black regions my also play a role. Observe how the black regions in Figure 6 appear shapeless when they are seen as grounds to the white vase, yet they appear shaped like profiles of faces when they are seen as figures. Similarly, observe how the white region appears shapeless when it is seen as the ground to the black profile faces, yet appears to be shaped like a vase when it is seen as figure.

Thus, regions appear shapeless at least near the edge they share with figures when they are seen as grounds even though the same regions appear shaped when they are perceived to be figures. How does figure-ground perception occur? The apparent shapelessness of the regions adjacent to figures has led to the proposal organization in vision essays on gestalt perception figure-ground perception results from a winner-take-all competition. Recent behavioral evidence shows that competition does occur e.

But what is competing? Some models propose that the competition occurs between edge units facing in opposite directions that exist everywhere in the visual field Kienker et al.

The edge units that win the competition are perceived as the boundaries of the figures, whereas those that lose the competition are suppressed. Other theorists contend that candidate shapes — that is, shapes that might be seen on opposite sides of an edge -- compete directly with each other. Experimental work investigating the competition is relatively new. More studies directed to uncovering the nature of the competition are necessary.

For instance, experiments investigating how organization in vision essays on gestalt perception cues alter the between-shape competition are needed to elucidate the mechanisms of figure-ground perception. When two regions share a border, perceptions other than figure-ground perception can and do occur Kennedy For instance, the shared border can appear to be an edge of a three-dimensional object, and the two regions could be perceived as different faces or surfaces of that object.

Or, one might perceive a shaped hole in that the surface in which the hole has been cut appears to be the near surface, but the hole appears to have shape.

Consider, for instance, a hand-shaped hole cut into a piece of metal. How will theories about perception change when we consider organization in vision essays on gestalt perception other possible outcomes? Edges separate surfaces in touch as well as in vision, and figure-ground perception occurs Kennedy There are analogous percepts in hearing, taste, and smell as well.

Do the same mechanisms produce figure-ground perception across the senses? Interactions between cooperative and competitive mechanisms have been proposed to play a key role in explaining many of these reversals. Can comparisons of the different types of ambiguous stimuli shed light on where and how competitive mechanisms operate in the brain? A lot is known about the development of depth perception, but there is little empirical work on the development of the configural cues, perhaps because the Gestalt Psychologists stipulated that they were innate.

What is the developmental trajectory of figure-ground perception? Recommended Organization in vision essays on gestalt perception Koffka, K. Principles of Gestalt psychology. From Fragments to Objects: