Interference and dominance in texture segregation: Hue, geometric form, and line orientation

Abstract

Five experiments were designed to test whether (1) lowering the similarity of elements within a region of texture (low-similarity arrays) would interfere with texture segregation, and (2) there would be dominance of one type of property difference over another in determining an observer's choice of boundary in two-boundary (ambiguous) displays. In Experiments 1 and 2, the interference question was assessed using stimuli formed from the dimensions hue and geometric form (circle/square or straight/curved novel shapes), The results indicated that when boundary judgments were based on form differences, segregation was significantly impaired by hue variation. However, hue segregations were not affected by form variation. In Experiments 3-5, the dominance question was examined using stimuli formed from hue and geometric form, as well as those formed from hue and line orientation (horizontal/vertical'[ Analyses revealed that there was no dominance of one type of property difference over another. Rather, observers' performance was completely predicted by the relative discriminabilities of the two boundaries. These findings support Beck's (1982) model of textural segmentation and call into question traditional notions of the preattentive stage of perceptual processing.The perception of separate regions of texture in the visual field is a process that proceeds automatically, with little or no apparent effort. In the phenomenological experience of casually scanning the real visual world, an observer is aware of vague regions of difference and hazy boundaries between indistinct forms. The precise properties of these forms-their hue, shape, orientation, spatial location, or pattern of movement-are not directly accessible to the observer in this casual state. However, given the requisite motivation (e.g., "Find your red-headed son in that mass of children"), the observer is quickly shifted into a directed state of perception, now able to "zoom in" on a specific property, or combination of properties, to the exclusion of others.This description of the phenomenon of perception fits nicely with the early feature-integration theory of object perception proposed by Treisman (Treisman & Gelade, 1980;Treisman & Paterson, 1984;Treisman & Souther, 1985). In that view, the automatic grouping together of Experiments I and 3 were conducted at Yale University, where the author was supported by a Natural Sciences and Engineering Research Council of Canada postdoctoral fellowship, and additional support from National Institute of Mental Health Grant MH 14229 to W. R. Gamer. The remaining experiments were conducted at St. Francis Xavier University and were supported by a Natural Sciences and Engineering Research Council of Canada operating grant to the author. The author thanks W. R. Gamer, Richard Ivry, and two anonymous reviewers for their helpful comments on an earlier draft of this paper. Thanks also to Annette MacArthur for help in running some of these experiments. Requests for reprints should be sent to Tara C. Callaghan, Department o...

Cross-dimensional perceptual selectivity

“…The results of Callaghan (1989) on texture segregation, however, do not support the horse-race model above. Even though Callaghan admits that there is no apparent mechanism that can explain the asymmetry, her data show that even when form differences are easier to discriminate than color differences (mean RT of 571 msec for "form" control condition vs. mean RT of 592 msec for "hue hard" control condition), the asymmetry in interference remains.…”

“…If attention is switched on the basis of the order of the availability of the local feature, it is expected that the asymmetry also will switch, so that form, and not color differences, produce interference. Yet, if the unique color continues to interfere even when it is harder to discriminate, the results would confirm Callaghan's (1989) findings.…”

“…Since the asymmetric interference was rather small and did not occur in all experiments, Pashler (1988) hardly discusses the implications of this asymmetry. However, texture segregation experiments of Callaghan (1989) confirm the asymmetry between form and color. When boundary judgments were based on form differences, segmentation was significantly impaired by color variation.…”

Visual search, visual streams, and visual architectures

“…If feature maps functioned independently, the orthogonal variations should have no effect. Results (Callaghan, 1984(Callaghan, , 1989Callaghan, Lasaga, & Gamer, 1986;Pashler, 1988) often show, however, significant loss of performance when an irrelevant feature is randomly varied.…”

Extending a class of motion stimuli to study multiattribute texture perception

“…Not surprisingly, some complex x-t plane arrangements produce strong impressions of two-dimensional textures (see, e.g., Figures 1 and 4 of Chubb & Sperling, 1988). As a result, we modified our class of multiattribute motion stimuli to study the role of visual attributes in textural grouping (Beck, 1966(Beck, , 1982Callaghan, 1989;Callaghan, Lasaga, & Garner, 1986;Garner & Feldoldy, 1970;Nothdurft, 1985;Olson & Attneave, 1970). In this paper, we follow closely the notation and exposition of our earlier paper on motion stimuli .…”