Cross-orientation masking in human color vision: Application of a two-stage model to assess dichoptic and monocular sources of suppression

Kim, Yeon Jin; Gheiratmand, Mina; Mullen, Kathy T.

doi:10.1167/13.6.15

Cited by 19 publications

(30 citation statements)

References 52 publications

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“…Contrast normalization, revealed as the perceptual effect called “cross orientation masking”, elevates thresholds across all orientations, broadening the orientation tuning of the masking317. The effect of cross orientation masking is stronger in colour than luminance vision1251 and acts to obscure the orientation tuning of the underlying colour detectors in masking experiments; for example, Medina and Mullen12 found no orientation tuning in the chromatic response functions using masking. For both chromatic and achromatic contrast, our bandwidth estimates at 1.5 c/deg (16 and 12 degs, for colour and luminance respectively) are narrower than those found previously from masking experiments, which are in the range of 26–30 degs for colour and 22–24 degs for luminance contrast at a mid-spatial frequency51314.…”

Section: Discussionmentioning

confidence: 99%

Orientation tuning in human colour vision at detection threshold

Gheiratmand

Mullen

2014

Sci Rep

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We measure the orientation tuning of red-green colour and luminance vision at low (0.375 c/deg) and mid (1.5 c/deg) spatial frequencies using the low-contrast psychophysical method of subthreshold summation. Orientation bandwidths of the underlying neural detectors are found using a model involving Minkowski summation of the rectified outputs of a bank of oriented filters. At 1.5 c/deg, we find orientation-tuned detectors with similar bandwidths for chromatic and achromatic contrast. At 0.375 c/deg, orientation tuning is preserved with no change in bandwidth for achromatic stimuli, however, for chromatic stimuli orientation tuning becomes extremely broad, compatible with detection by non-oriented colour detectors. A non-oriented colour detector, previously reported in single cells in primate V1 but not psychophysically in humans, can transmit crucial information about the color of larger areas or surfaces whereas orientation-tuned detectors are required to detect the colour or luminance edges that delineate an object's shape.

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Section: Discussionmentioning

confidence: 99%

Orientation tuning in human colour vision at detection threshold

Gheiratmand

Mullen

2014

Sci Rep

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“…input contrast in the amblyopic eye, and Z, p, and q are model parameters, representing, respectively, the normalization parameter and the rate of acceleration of the nonlinear contrast responses on the numerator and denominator, here fixed at 0.01, 2.4, and 2. [35][36][37][38] For a range of contrasts C F in the fellow eye, we simulated the matching contrast in the amblyopic eye C A , such as resp F ¼ resp A for the successive and simultaneous matching conditions, according to four possible mechanisms, by adding an extra parameter in different places of the response of the amblyopic eye resp A . In the normalization term, the contrast of the other eye: whether the amblyopic C A0 or fellow C F0 was set to 0% for the successive matching simulation and to 70% for the simultaneous matching.…”

Section: Appendixmentioning

confidence: 99%

Is Suppression Just Normal Dichoptic Masking? Suprathreshold Considerations

Reynaud

Hess

2016

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. Amblyopic patients have a deficit in visual acuity and contrast sensitivity in their amblyopic eye as well as suppression of the amblyopic eye input under binocular viewing conditions. In this study we wanted to assess the origin of the amblyopic suppression by studying the contrast perception of the amblyopic eye at suprathreshold levels under binocular and monocular viewing.METHODS. Using a suprathreshold contrast matching task in which the reference and target stimuli were presented to different eyes either simultaneously or successively, we measured interocular contrast matching in 10 controls and 11 amblyopes (mean age 35 6 15; 5 strabismics; 3 anisometropes; 3 mixed). This was then used as an index of the binocular balance across spatial frequency and compared against the contrast sensitivity ratio measured with the same stimuli.RESULTS. We observed that binocular matching becomes more imbalanced at high spatial frequency for amblyopes, compared with controls; that this imbalance did not depend in either group on whether the stimuli were presented simultaneously or successively; and that for both modes of presentation the matching balance correlates well with the interocular contrast sensitivity ratio (mean correlation coefficient of the slopes R ¼ 0.7125). CONCLUSIONS.The results from our amblyopes show comparable losses of contrast perception at and above threshold under these binocular viewing conditions across a wide spatial frequency range, much stronger than that observed for our controls. This occurs under conditions in which there should be no dichoptic masking. Furthermore, the matching contrast could be well predicted by the monocular contrast sensitivity. Altogether, this suggests that amblyopic suppression cannot be explained by normal dichoptic masking but rather an attenuation of the input.Keywords: interocular matching, amblyopia, qCSF, contrast constancy, suppression A mblyopia involves a loss of monocular vision and a suppression of the amblyopic eye's function under binocular viewing. There is debate about the causal relationship between these two factors. One possibility is that the suppression seen in amblyopia is a consequence of combining normal dichoptic masking with elevated contrast threshold in the amblyopic eye. Dichoptic masking depends on the level of suprathreshold contrast, so an elevated threshold in one eye (e.g., the amblyopic eye) would automatically result in imbalanced masking at all contrast levels, such that one eye (e.g., the fellow fixing eye) will always dominate over the other. We refer to this as the threshold hypothesis, as implemented by the offset subtraction model (see Appendix) where the primary deficit is the amblyopia and the secondary consequence is the binocular dysfunction.1,2 An alternate explanation is that the suppression results from anomalously large dichoptic inhibition of the amblyopic eye's input by the fellow fixing eye's input that in the long term results in a contrast threshold elevation in the amblyopic eye. We refer to this as the...

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“…In sum, relative to component gratings, color plaids have lower perceived contrast summation than achromatic plaids and this chromatic summation difference is greater at the medium-spatial frequency and smaller at the low-spatial frequency. These results may be reflective of two separate processes: greater cross-orientation suppression in color vision (Kim et al, 2013; Medina & Mullen, 2009) and increased cross-orientation summation for low compared with medium-spatial frequency color stimuli (Gheiratmand et al, 2013, 2016; Gheiratmand & Mullen, 2014). …”

Section: Resultsmentioning

confidence: 91%

“…While achromatic suppression may be due to subcortical magnocellular sources, monocular chromatic cross-orientation suppression is likely found in the cortex (Kim et al, 2013; Solomon & Lennie, 2005). The lower perceived contrast summation for chromatic compared with achromatic plaids that we find complements these previous findings of increased cross-orientation suppression with both monocular and binocular stimuli.…”

Section: Discussionmentioning

confidence: 99%

The Whole is Other Than the Sum: Perceived Contrast Summation Within Color and Luminance Plaids

Cherniawsky

Mullen

2016

i-Perception

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The apparent contrast of a plaid is a reflection of the neural relationship between the responses to its two orthogonal component gratings. To investigate the perceived contrast summation of the responses to component gratings in plaids, we compared the apparent contrasts of monocular plaids to a component grating presented alone across chromaticity and spatial frequency. Observers performed a contrast-matching task for red–green color and luminance stimuli at low- and medium-spatial frequencies. Using the measured points of subjective equality between plaids and gratings, we evaluate perceived contrast summation across conditions, which may vary between 1 (no summation) and 2 (full summation). We show that achromatic plaids have higher perceived contrast summation than chromatic plaids. The greatest difference occurs at the medium-spatial frequency, with summation highest for achromatic plaids (1.87) and lowest for chromatic plaids (1.49), while at low-spatial frequencies, there is a smaller summation difference between achromatic (1.72) and chromatic (1.65) plaids. These results are consistent with recent theories of distinct cross-orientation suppression and summation mechanisms in color and luminance vision. Two control experiments for binocular versus monocular viewing, and the overall size of the stimulus patches did not reveal any differences from our main results.

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Cross-orientation masking in human color vision: Application of a two-stage model to assess dichoptic and monocular sources of suppression

Cited by 19 publications

References 52 publications

Orientation tuning in human colour vision at detection threshold

Orientation tuning in human colour vision at detection threshold

Is Suppression Just Normal Dichoptic Masking? Suprathreshold Considerations

The Whole is Other Than the Sum: Perceived Contrast Summation Within Color and Luminance Plaids

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