Simultaneous density contrast is bidirectional

Sun, Hua-Chun; Baker, Curtis L.; Kingdom, Frederick A. A.

doi:10.1167/16.14.4

Cited by 5 publications

(28 citation statements)

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“…Note that the high numerosity conditions in these studies may fall into the density regime as well (Aida et al, 2015;Burr & Ross, 2008). Also one should note that other studies have suggested a common basis for coding density and numerosity (Dakin et al, 2011;Morgan et al, 2014;Raphael & Morgan, 2016;Sun et al, 2016;Sun et al, 2017;Tibber et al, 2012). Therefore, it remains unclear whether depth can affect density perception directly.…”

Section: Introductionmentioning

confidence: 74%

“…Stimuli consisted of quasi-randomly placed, nonoverlapping uniform discs, termed dots, as described in our previous studies (Sun et al, 2016;Sun et al, 2017). Half of the dots were black (7 cd/m 2 ) and half white (115 cd/m 2 ), each with a diameter of 0.058, and placed on a mid-gray background of 61 cd/m 2 .…”

Section: Stimulimentioning

confidence: 99%

“…A variety of textures are encountered in everyday object surfaces and scenes, and a salient attribute we routinely perceive is texture density (henceforth, ''density''). Most studies of density encoding are performed under 2D conditions, since density is conventionally defined as the number of elements per unit visual area Dakin, Tibber, Greenwood, Kingdom, & Morgan, 2011;Durgin, 2001;Durgin & Hammer, 2001;Sun, Baker, & Kingdom, 2016;Tibber, Greenwood, & Dakin, 2012). There is evidence that density information is coded via multiple channels selective to different ranges of density (Sun et al, 2016;Sun, Kingdom, & Baker, 2017), in a manner that is separable from the processing of spatial frequency and luminance contrast (Durgin, 2001;Durgin & Hammer, 2001;Sun et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…We have tested whether density information is simply represented at a 2D retinotopic level, as has been suggested (Bell et al, 2015;Dakin et al, 2011), or whether there are binocular effects on density computation as other evidence implies (e.g., the effect of depth on numerosity, the influence of density on depth, and interocular transfer of density adaptation). We have examined this issue using simultaneous density contrast, or SDC, the phenomenon in which the perceived density of a texture region is altered by a surround of different density (Sun et al, 2016). Our previous study revealed that SDC is bidirectional; that is, sparser surrounds increase perceived density and denser surrounds decrease it (Sun et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…We have examined this issue using simultaneous density contrast, or SDC, the phenomenon in which the perceived density of a texture region is altered by a surround of different density (Sun et al, 2016). Our previous study revealed that SDC is bidirectional; that is, sparser surrounds increase perceived density and denser surrounds decrease it (Sun et al, 2016). The use of SDC allows us to manipulate surround properties (e.g., stereo-disparity) independently from those of the center, so that the measurement of density perception in the center is not confounded with other variables.…”

Section: Introductionmentioning

confidence: 99%

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Simultaneous density contrast and binocular integration

2018

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Most research on texture density has utilized textures rendered as two-dimensional (2D) planar surfaces, consistent with the conventional definition of density as the number of texture elements per unit area. How the brain represents texture density information in the three-dimensional (3D) world is not yet clear. Here we tested whether binocular information affects density processing using simultaneous density contrast (SDC), in which the perceived density of a texture region is changed by a surround of different density. We considered the effect on SDC of two types of binocular information: the stereoscopic depth relationships and the interocular relationships between the center and surround textures. Observers compared the perceived density of two random dot patterns, one with a surround (test stimulus) and one without (match), using a 2AFC staircase procedure. In Experiment 1 we manipulated the stereo-depth of the surround plane systematically from near to far, relative to the center plane. SDC was reduced when the difference in stereo-depth between test center and surround increased. In Experiment 2 we spread the surround dots randomly across a stereo-depth volume from small to large volume sizes, and found that SDC was slightly reduced with volume size. The decrease of SDC in both experiments was observed with dense surrounds only, but not with sparse surrounds. In the last experiment we presented center and surround in the same depth plane but dichopticly, monopticly, and binocularly. A strong interocular transfer of SDC was found in the dichoptic condition. Together these results show that texture density processing is sensitive to binocularity.

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Section: Introductionmentioning

confidence: 74%

Section: Stimulimentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Simultaneous density contrast and binocular integration

2018

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Perceived regularity of a texture is influenced by the regularity of a surrounding texture

Sun

Kingdom

Baker

2019

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Previous studies have shown that texture regularity is adaptable, and have suggested that texture regularity might be coded by the peakedness of the underlying spatial frequency distribution. Here we demonstrate the related phenomenon of simultaneous regularity contrast (SRC), in which the perceived regularity of a central texture is influenced by the regularity of a surrounding texture. We presented center-surround arrangements of textures and measured the perceived regularity of the centre, using a centre-only comparison stimulus and a 2AFC procedure. From the resulting psychometric functions the SRC was measured as the difference between test and comparison regularity at the PSE (point of subjective equality). Observers generally exhibited asymmetric bidirectional SRC, in that more regular surrounds decreased the perceived regularity of the centre by between 20–40%, while less regular surrounds increased the perceived regularity of the centre by about 10%. Consistent with previous studies, a wavelet spatial frequency (SF) analysis of the stimuli revealed that their SF distributions became sharper with increased regularity, and therefore that distribution statistics such as kurtosis and SF bandwidth might be used to code regularity.

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Dynamics of contextual modulation of perceived shape in human vision

Gheorghiu

Kingdom

2017

Sci Rep

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In biological vision, contextual modulation refers to the influence of a surround pattern on either the perception of, or the neural responses to, a target pattern. One studied form of contextual modulation deals with the effect of a surround texture on the perceived shape of a contour, in the context of the phenomenon known as the shape aftereffect. In the shape aftereffect, prolonged viewing, or adaptation to a particular contour's shape causes a shift in the perceived shape of a subsequently viewed contour. Shape aftereffects are suppressed when the adaptor contour is surrounded by a texture of similarlyshaped contours, a surprising result given that the surround contours are all potential adaptors. Here we determine the motion and temporal properties of this form of contextual modulation. We varied the relative motion directions, speeds and temporal phases between the central adaptor contour and the surround texture and measured for each manipulation the degree to which the shape aftereffect was suppressed. Results indicate that contextual modulation of shape processing is selective to motion direction, temporal frequency and temporal phase. These selectivities are consistent with one aim of vision being to segregate contours that define objects from those that form textured surfaces.In natural scenes, objects rarely occur in isolation, more often than not surrounded by other objects or set against textured surfaces. The human visual system is tasked with extracting and recognizing the shapes of objects from such feature-reach textured backgrounds 1 . Recent psychophysical and computational studies have shown that textures can modulate the perception of the shapes of contours they surround 2-10 . Consider Fig. 1a which shows an anecdotal example from Galli and Zama 11 of how texture influences the perception of a simple object such as a triangle. When presented in isolation the sides of the triangle are equally salient but when surrounded by a texture (e.g. gratings) the side parallel to the grating bars is perceived as part of the grating/texture not the triangle. We seem unable to perceive the side of the triangle as separate from the grating even when aware that the line is part of a triangle. The related example in Fig. 1b shows that when contours are flanked by several similar-shaped contours it is difficult to perceive the shape of an individual contour. In Fig. 1c, a rectangular shape is partly embedded in a grating, and the embedded parts appear to belong to the grating, as demonstrated by Kanizsa 12 . These simple demonstrations suggest that contours that are parts of textures are processed separately from contours that exist on their own. Put another way, it would appear that contours that are part of textures are prevented from acting as contours that define the shapes of objects.How might this come about? One idea is that neurons in the visual cortex that possess what has been termed 'extra classical receptive-fields' (ERFs) are responsible. A significant number of these neurons are suppressed by...

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Simultaneous density contrast is bidirectional

Cited by 5 publications

References 50 publications

Simultaneous density contrast and binocular integration

Simultaneous density contrast and binocular integration

Perceived regularity of a texture is influenced by the regularity of a surrounding texture

Dynamics of contextual modulation of perceived shape in human vision

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