Pulling the other one: 1st- and 2nd-order visual information interact to determine perceived location

Whitaker, David; McGraw, Paul V.; Keeble, D.R.T.; Skillen, Jennifer

doi:10.1016/j.visres.2003.09.014

Cited by 9 publications

(14 citation statements)

References 40 publications

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“…Thus performance with the bell cannot be characterized simply in terms of a shift in refer ence point (although the results do suggest a shift of the reference location as well, relative to the bell's overall COG). The results are considered with respect to three theories of distance judgment: Morgan et al (1990), Whitaker et al (1996Whitaker et al ( , 2004, and Burbeck and Hadden (1993). Morgan et al (1990) proposed a mechanism composed of higher-order 'eclectic units' that determines the spatial position of objects and texture patches.…”

Section: Discussionmentioning

confidence: 99%

“…Morgan et al (1990) noted that for larger-scale distance judgments, such as between two target squares embedded within different objects, only the COG of each of the large objects may be available. Whitaker et al (1996Whitaker et al ( , 2004 Whitaker et al (1996Whitaker et al ( , 2004 proposed a spatial filter mechanism that pools positional responses at different spatial scales. Whitaker et al (2004) examined the effects of mod ulating the carrier and envelope of a Gabor patch in an alignment task.…”

Section: The Mechanism Of Morgan Et Al (1990)mentioning

confidence: 99%

“…Whitaker et al (1996Whitaker et al ( , 2004 Whitaker et al (1996Whitaker et al ( , 2004 proposed a spatial filter mechanism that pools positional responses at different spatial scales. Whitaker et al (2004) examined the effects of mod ulating the carrier and envelope of a Gabor patch in an alignment task. Observers were asked to make one of two horizontal-position alignment judgments of a central Gabor patch, relative to two other, vertically flanking, Gabors.…”

Section: The Mechanism Of Morgan Et Al (1990)mentioning

confidence: 99%

“…Whitaker et al (2004) noted that observers' responses were influenced by the entire Gabor patch, even when the alignment task required them to selectively attend to either the carrier or the envelope of the Gabor. These biases were consistent with the use of the respective centroids of high-spatial-frequency and low-spatial-frequency defined modulations (Whitaker et al 1996(Whitaker et al , 2004. Whitaker et al (2004, page 285) pointed out that this may be due to ''non-volitional, automatic combinatorial processes within the human visual system''.…”

Section: The Mechanism Ofmentioning

confidence: 99%

“…A reference point for assigning a location to an object is often the centroid of the shape (also known as center of gravity, COG) Kowler 2003, 2004;Watt andMorgan 1983a, 1983b;Westheimer and McKee 1977;Whitaker et al 1996Whitaker et al , 2004. The visual system can estimate the COG by averaging the luminance distribu tion of a target shape, or by averaging its local contrast energy (Guez et al 1994;McGowan et al 1998;Melcher and Kowler 1999;Vishwanath and Kowler 2003).…”

Section: Introductionmentioning

confidence: 99%

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The Role of Part Structure in the Perceptual Localization of a Shape

2006

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Abstract. The process of object localization may be accomplished with respect to a particular reference location, such as the center of gravity, COG (eg Vishwanath and Kowler, 2003 Vision Research 43 1637-1653. Here, we investigated how part structure affects an object's reference location. The reference location was evaluated with a measure of the illusory displacement of an internal target element embedded within a larger object (Morgan et al, 1990 Vision Research 30 1793 -1810. To examine whether the reference location is different for shapes with part structure, two shapes were tested: circle (small and large; no part structure) and bell (shape with two parts, one larger than the other). Results were examined with respect to two predictions: either the location of an object is based on its shape as a whole, disregarding part structure (ie a single, overall COG), or the parts are processed separately (different COGs).With the circles, the results showed a systematic illusory displacement of the internal target toward the COG. With the bell, the illusion was significantly weaker than with both circleseven though the main part of the bell had the same size as the small circle, and its horizontal axis had the same extent as the large circle. Moreover, the distance judgments for the bell were consistent with a (weaker) reference point being located at the COG of the larger part, rather than at the COG of the entire bell. These results show that the part structure of a shape plays a role in the representation of its location, and that for complex shapes the perceived location of an embedded element depends more on the parts within which it is embedded, rather than on the whole shape.

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Section: Discussionmentioning

confidence: 99%

Section: The Mechanism Of Morgan Et Al (1990)mentioning

confidence: 99%

Section: The Mechanism Of Morgan Et Al (1990)mentioning

confidence: 99%

Section: The Mechanism Ofmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Role of Part Structure in the Perceptual Localization of a Shape

2006

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Collinearity improves alignment in amblyopia as well as in normal vision

Popple¹,

Yuen²,

Levi³

2007

Vision Research

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In normal vision, three contrast patches containing black and white bars are aligned more precisely when the bars are collinear across the patches [Popple, A., Polat, U., & Bonneh, Y. (2001). Collinear effects on 3-Gabor alignment as a function of spacing, orientation and detectability. Spatial Vision, 14(2), 139-150]. Normally, offsets between the bars in successive patches make the configuration appear tilted, but this effect is reduced in amblyopia [Popple, A. V., & Levi, D. M. (2000). Amblyopes see true alignment where normal observers see illusory tilt. Proceedings of the National Academy of Science of the United States of America, 97(21), 11667-11672]. Our aim was to examine whether collinear bars nonetheless improve the precision of alignment in amblyopia. In a sample of 13 amblyopes, we found that collinear bars did indeed improve the precision of alignment in amblyopia, although both alignment bias and thresholds were higher in the amblyopic eyes for both collinear and non-collinear bars.

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Ecologically valid combinations of first- and second-order surface markings facilitate texture discrimination

et al. 2007

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Natural scenes contain localized variations in both first-order (luminance) and second-order (contrast and texture) information. There is much evidence that first- and second-order stimuli are detected by distinct mechanisms in the mammalian visual system. However, in natural scenes the two kinds of information tend to be spatially correlated. Do correlated and uncorrelated combinations of first- and second-order stimuli differentially affect perception? To address this question we employed orientation-modulated textures in which observers were required to discriminate the spatial frequency of the texture modulation. The textures consisted of micropatterns defined as either local variations in luminance (first-order) or luminance contrast (second-order). Performance was robust with textures composed of only first-order micropatterns, but impossible with only second-order micropatterns. However, when the second-order micropatterns were combined with the first-order micropatterns, they enhanced performance when the two were spatially correlated, but impaired performance when the two were spatially uncorrelated. We conclude that local second-order information may enhance texture modulation discrimination provided it is combined with first-order information in an ecologically valid manner.

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Pulling the other one: 1st- and 2nd-order visual information interact to determine perceived location

Cited by 9 publications

References 40 publications

The Role of Part Structure in the Perceptual Localization of a Shape

The Role of Part Structure in the Perceptual Localization of a Shape

Collinearity improves alignment in amblyopia as well as in normal vision

Ecologically valid combinations of first- and second-order surface markings facilitate texture discrimination

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