Glass-pattern detection is tuned for stereo-depth

Khuu, Sieu K.; Hayes, Anthony

doi:10.1016/j.visres.2005.02.019

Cited by 10 publications

(5 citation statements)

References 41 publications

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“…Finally, our observations suggest that contour grouping in depth might involve the linking of a number of depth selective mechanisms that are tuned for a range of binocular disparities. This is similar to Hess and Field (1995),and to Khuu and Hayes (2005), who showed that the integration of local orientations occurs over large depth separations in the perception of global form in Glass patterns.…”

Section: Resultssupporting

confidence: 86%

The perception of three-dimensional contours and the effect of luminance polarity and color change on their detection

2016

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In the present study we investigated the detectability of three-dimensional (3D) cocircular contours defined by binocular disparity and established the influence of a number of stimulus factors to their perception. In Experiment 1 we examined the depth range over which local elements are grouped in depth, and whether contour detectability systematically changed with the degree to which they are oriented in depth. We found that increasing the orientation of curved contours in depth improved detection performance. In Experiment 2, we examined the degree to which contour detection was disrupted by varying their continuity in depth by jittering the local depth position of contour elements. Detection performance declined with the increasing displacement of local contour elements in depth away from the depth orientation of the contour. Experiments 3 and 4 ascertained whether a detection advantage is afforded to 3D contours defined by local variations in luminance polarity and color. Local color and polarity differences can disrupt the two-dimensional grouping of local contour elements on the basis of similarity, but we tested whether continuity in depth facilitates grouping of contour elements differing in polarity and color. We found no detection advantage for 3D contours defined by local color and polarity variations, suggesting binocular disparity does not facilitate grouping in depth when local elements differ in color and polarity. These findings further suggest the visual system uses binocular disparity to detect contours, but is likely to involve systems tuned to luminance polarity and color.

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Section: Resultssupporting

confidence: 86%

The perception of three-dimensional contours and the effect of luminance polarity and color change on their detection

2016

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“…[ 29 , 31 , 34 ]) by changing the ratio between dipoles oriented in the pattern direction (signal dipoles), and those that have random orientations, until the global structure can be just detected ( Fig 1B ). Typically Glass detection thresholds are 15–25% signal [ 27 , 38 , 45 ].…”

Section: Introductionmentioning

confidence: 99%

Exposure to Organic Solvents Used in Dry Cleaning Reduces Low and High Level Visual Function

2015

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PurposeTo investigate whether exposure to occupational levels of organic solvents in the dry cleaning industry is associated with neurotoxic symptoms and visual deficits in the perception of basic visual features such as luminance contrast and colour, higher level processing of global motion and form (Experiment 1), and cognitive function as measured in a visual search task (Experiment 2).MethodsThe Q16 neurotoxic questionnaire, a commonly used measure of neurotoxicity (by the World Health Organization), was administered to assess the neurotoxic status of a group of 33 dry cleaners exposed to occupational levels of organic solvents (OS) and 35 age-matched non dry-cleaners who had never worked in the dry cleaning industry. In Experiment 1, to assess visual function, contrast sensitivity, colour/hue discrimination (Munsell Hue 100 test), global motion and form thresholds were assessed using computerised psychophysical tests. Sensitivity to global motion or form structure was quantified by varying the pattern coherence of global dot motion (GDM) and Glass pattern (oriented dot pairs) respectively (i.e., the percentage of dots/dot pairs that contribute to the perception of global structure). In Experiment 2, a letter visual-search task was used to measure reaction times (as a function of the number of elements: 4, 8, 16, 32, 64 and 100) in both parallel and serial search conditions.ResultsDry cleaners exposed to organic solvents had significantly higher scores on the Q16 compared to non dry-cleaners indicating that dry cleaners experienced more neurotoxic symptoms on average. The contrast sensitivity function for dry cleaners was significantly lower at all spatial frequencies relative to non dry-cleaners, which is consistent with previous studies. Poorer colour discrimination performance was also noted in dry cleaners than non dry-cleaners, particularly along the blue/yellow axis. In a new finding, we report that global form and motion thresholds for dry cleaners were also significantly higher and almost double than that obtained from non dry-cleaners. However, reaction time performance on both parallel and serial visual search was not different between dry cleaners and non dry-cleaners.ConclusionsExposure to occupational levels of organic solvents is associated with neurotoxicity which is in turn associated with both low level deficits (such as the perception of contrast and discrimination of colour) and high level visual deficits such as the perception of global form and motion, but not visual search performance. The latter finding indicates that the deficits in visual function are unlikely to be due to changes in general cognitive performance.

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“…Glass patterns (after Glass, 1969) are random dot stimuli consisting of dot-pairs with the same polarity (dipoles) configured to convey global structure (e.g., concentric structure in Figure 1B ). Glass patterns are particularly useful because their analysis by the visual system is well understood (e.g., Gallant et al, 1996; Bair et al, 2002), and reflects both local and global levels of computation: the orientation of local dipoles is initially extracted, and then combined at a later stage where the global form of the pattern can be determined (e.g., Wilson and Wilkinson, 1998; MacGraw et al, 2004; Wilson et al, 2004; Khuu and Hayes, 2005; Khuu et al, 2011). Thus, Glass pattern stimuli are ideal for investigating the processing of global form as they provide a direct probe of the mechanisms responsible for form integration that is not driven by top down influences unlike previously used stimuli (mentioned above) such as illusory contours and faces.…”

Section: Introductionmentioning

confidence: 99%

The processing of coherent global form and motion patterns without visual awareness

Chung

Khuu

2014

Front. Psychol.

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In the present study we addressed whether the processing of global form and motion was dependent on visual awareness. Continuous flash suppression (CFS) was used to suppress from awareness global dot motion (GDM) and Glass pattern stimuli. We quantified the minimum time taken for both pattern types to break suppression with the signal coherence of the pattern (0, 25, 50, and 100% signal) and the type of global structure (rotational, and radial) as independent variables. For both form and motion patterns increasing signal coherence decreased the time required to break suppression. This was the same for both rotational and radial global patterns. However, GDM patterns broke suppression faster than Glass patterns. In a supplementary experiment, we confirmed that this difference in break times is not because of the temporal nature of GDM patterns in attracting attention. In Experiment 2, we examined whether the processing of dynamic Glass patterns were similarly dependent on visual awareness. The processing of dynamic Glass patterns is involves both motion and form systems, and we questioned whether the interaction of these two systems was dependent on visual awareness. The suppression of dynamic Glass patterns was also dependent on signal coherence and the time course of suppression break resembled the detection of global motion and not global form. In Experiment 3 we ruled out the possibility that faster suppression break times was because the visual system is more sensitive to highly coherent form and motion patterns. Here contrast changing GDM and Glass patterns were superimposed on the dynamic CFS mask, and the minimum time required for them to be detected was measured. We showed that there was no difference in detection times for patterns of 0 and 100% coherence. The advantage of highly coherent global motion and form patterns in breaking suppression indicated that the processing and interaction of global motion and form systems occur without visual awareness.

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Glass-pattern detection is tuned for stereo-depth

Cited by 10 publications

References 41 publications

The perception of three-dimensional contours and the effect of luminance polarity and color change on their detection

The perception of three-dimensional contours and the effect of luminance polarity and color change on their detection

Exposure to Organic Solvents Used in Dry Cleaning Reduces Low and High Level Visual Function

The processing of coherent global form and motion patterns without visual awareness

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