Aggregation and Unit Formation in the Perception of Moving Collinear Lines

Gillam, Barbara; Grant, T. J.

doi:10.1068/p130659

Cited by 15 publications

(10 citation statements)

References 6 publications

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“…Correspondence should be addressed to D. D. Kurylo, Psychology Department, Bowdoin College, Brunswick, ME 0401 I (e-mail: dkurylo@polar.bowdoin.edu). (Gillam & Grant, 1984). In this case, grouping processes are sensitive to distances between elements, and grouping assignment is based on the ratio of element separation (Gillam, 1981).…”

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Time course of perceptual grouping

Kurylo

1997

Perception & Psychophysics

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An investigation was made of the time course of perceptual grouping that is based on two qualitatively different spatial relationships: proximity and alignment. An index of grouping capacity was used to assess the processing time required before a backward pattern mask interfered with grouping. Stimuli consisted of bistable arrays of disjunct dots that were followed by a mask. Grouping cues, either proximity or alignment, were randomly assigned to either the horizontal or vertical orientation, and subjects indicated whether the dots appeared grouped as a series of horizontal or vertical lines. Spatial metrics of the cues were systematically altered until they no longer served as a cue for grouping, thereby determining the grouping threshold. The stimulus onset asynchrony (SOA)of the mask, relative to the test stimulus, ranged from 33.3 to 150 msec. The SOAat which grouping thresholds first became elevated identified the point at which the mask first interfered with the grouping process, thereby identifying the processing time required for grouping by the specified cue. The processing time for grouping by proximity and alignment differed significantly, requiring means of 87.6and 118.8msec, respectively, for processing to be completed. These measurements serve to identify the processing time necessary for spatially integrating stimulus elements into unified forms, thereby delineating temporal constraints at this stage of visual processing.In order to organize complex stimuli in preparation for object recognition, the visual system quickly and automatically associates and segregates elements of the visual scene. To accommodate novel stimuli with speed and accuracy, the process ofgrouping likely follows established algorithms that mediate grouping strategies. These algorithms operate by extracting relevant information from the stimuli and then applying a set ofcriteria to that information which specify the grouping arrangement best suited for form identification. Although many of the characteristics associated with perceptual grouping have been described, the principles by which grouping functions, and the time course of its operation, are not well understood.Grouping strategies are based on several characteristics of stimuli, including feature similarities, such as color or element shape, and spatial relationships, such as element proximity or regularity. The present study examined grouping that is based on two spatial relationships among stimulus elements: element proximity and element alignment. In each case, a single spatial parameter was systematically altered while observers made judgments about the manner in which elements appeared to be grouped. In this way, the association between a specific spatial metric and the process of grouping was isolated.Grouping by element proximity and element alignment differ qualitatively in the nature of the spatial cue from which grouping is derived. Grouping by proximity (Rush, 1937) is based on the tendency for more proximal images to produce unified configurations, and for...

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confidence: 99%

Time course of perceptual grouping

Kurylo

1997

Perception & Psychophysics

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“…Column 2) (Gillam & Grant, 1984). The lines appeared to slip laterally in opposite directions as they rotated.…”

Section: Does Perceptual Growitg Necessarily Entail the Formation Of mentioning

confidence: 93%

“…but whose parallelism is nevmhelcss perfectly evident under all conditions. This is even more problematic in the case of collinear lines (Gillam & Grant, 1984). The first column in Figure 3 (down to 3d) shows mean fragmentation time (in seconds) for collinear lines as a function of gap size.…”

Section: On "Emergent Features"?mentioning

confidence: 97%

“…Unlike laterally separated lines, collincar lines show linle Fragmentation as a function of separation and it might be tempting to attribute this to the emergent fea- and time during which nonfigidity was reported (Column 2) for collinear (or vertically displaced) lines as a function of their separation. (Gillam & Grant, 1984) ture of collinearity. However, the same strong grouping is found when the lines have small but quite perceptible degrees of noncollinearity (see Figure 3e).…”

Section: On "Emergent Features"?mentioning

confidence: 99%

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The status of perceptual grouping 70 years after Wertheimer

Gillam

1992

Australian Journal of Psychology

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Modem studies of pmeptual grouping or coherence arc described and their theoretical implications discussed. The concept of "Riignantz" br "good figure" and its modem derivatives are shown to be inadequate in accounting for grouping data. It is shown that grouping is not an all-or-none phenomenon in that contour grouping may occur with respect to some perceptual responses while independence is found for others. In general the notion that grouping arises from "emergent features" is not considered useful in accounting for the data in simpk two-.lint figures and an alternative view, b a d on cooperative neural connections, is prooposed. Global emergent features art. however. shown to be a factor in grouping within some complex configurations. It is suggested that lateral relationships among contours may function independently of terminator relationships in influencing perceptual coherence. However, subjective contours form more readily across the collinear terminators of poorly grouped lines than across the same terminators of coherent lines. This "paradox" makes ecological sense. Finally, converging operations among different methods of measuring perceptual coherence are illustrated.Gestalt Psychologists (Wertheimer, 1923/1958) first drew attention to the fact that perception is highly organised. They demonstrated this using meaningless arrays of tines and dots in order to illustrate what we would now call "bottom-up" tendencies to connect elements in certain ways ralhcr than others. These tendencies constitute the Gestalt grouping principles -a descriptive account of grouping which has always been featured in elementary text books although despised by mainstream behaviourist psychology for many.years. An active Gestalt tradition, deriving largely from the influence of Benussi, survived only in Italy. However in recent years there has been an extraordinary burgeoning of interest once again in the problems of perceptual organisation which concerned the Gestaltists. At the beginning of the cognitive revolution there were several attempts to define the Gestalt concept of "good figure" or "simplicity" in information theory terms (Attneave. 1954; Hochberg & Brooks, IW).' An attempt was made to subsume all the Gestalt principles under one -the minimum principle -which asserts that the preferred resolution is the one which contains the least information. For example. perception of the classic drawing of a Necker cube as a three-dimensional figure is said to be preferred to perception of it as a twodimtnsional array of imgular shapes and angles because the three-dimensional rcsolution contains less information, that is, it has a more redundant description. The minimurn principle has been developed into a more formal theory of perceptual structure by von Leeuwenberg (1971), Restle (1 979), and Gamer (1 970), who provided a more sophisticated analysis of redundancy?About 25 years ago the rich Italian Gestalt tradition was discovered in the U.S.A. and elsewhere and attention was once more drawn to the phenomena rather than the...

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“…Using the rotational linkage criterion, Gillam and colleagues have shown that the grouping of two lines is influenced by a number of stimulus factors including: (a) relative line orientation (Gillam,[20]); (b) line separation relative to length (Gillam,[23]; Gillam and Grant Jr., [24]); (c) axis of rotation (Gillam and McGrath,[18]); and (d) common vanishing point with a surrounding frame (Gillam and Broughton, [25]). A general discussion of this approach to grouping can be found in Gillam [26].…”

Section: Introductionmentioning

confidence: 99%

Redundant Symmetry Influences Perceptual Grouping (as Measured by Rotational Linkage)

Gillam

2017

Symmetry

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Symmetry detection has long been a major focus of perception research. However, although symmetry is often cited as a "grouping principle", the effect of symmetry on grouping, an important form of perceptual organization, has been little measured. In past research, we found little spatio-temporal grouping for oblique lines symmetric around a horizontal axis during ambiguous rotary motion in depth. Grouping was measured by the degree to which the ambiguous motion direction was resolved for two elements in common (rotational linkage). We hypothesized that symmetry-based grouping would be stronger if symmetry was redundant i.e., carried by elements of greater complexity. Using the rotational linkage measure, we compared grouping for horizontally symmetric simple oblique lines and for lines composed of multiple conjoined orientations and found greater grouping for the more complex symmetric lines. A control experiment ruled out possible confounding factors and also showed a grouping effect of vertically aligned endpoints. We attribute the stronger grouping effect of redundant symmetry to the fact that it has a lower probability than does simple symmetry of arising from an accidental environmental arrangement.

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Aggregation and Unit Formation in the Perception of Moving Collinear Lines

Cited by 15 publications

References 6 publications

Time course of perceptual grouping

Time course of perceptual grouping

The status of perceptual grouping 70 years after Wertheimer

Redundant Symmetry Influences Perceptual Grouping (as Measured by Rotational Linkage)

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