The Verriest Lecture: Color lessons from space, time and motion

Shevell, Steven K.

doi:10.1364/josaa.29.00a337

Cited by 8 publications

(6 citation statements)

References 39 publications

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“…In this case, the presence of color would increase veridical perception. This result would be inconsistent with the ''linking feature'' hypothesis and instead would support the view that binding errors depend on an ambiguity-resolving process driven by the overall feature correspondence among all central and peripheral objects (Shevell, 2012). This result has been found for object shape.…”

Section: Introductioncontrasting

confidence: 80%

“…The results here show that feature-binding errors in the periphery are more common in the single-chromaticity conditions (all-achromatic, all-red, and all-green conditions) than in the r/g chromatic condition, contrary to the ''linking feature'' prediction. These results instead are consistent with feature-binding errors that depend, at least in part, on the overall feature correspondence among individual features in the central and peripheral areas (Shevell, 2012;Sun, 2011). Consider each single-chromaticity condition.…”

Section: Theoretical Implicationssupporting

confidence: 54%

“…When all of the objects in the center and periphery are the same shape (e.g., all squares, so 100% shape correspondence), then observers perceive peripheral illusory motion frequently (80% or more of the time; Sun, 2011). If shape correspondence among central and peripheral objects is reduced to 50%, 25%, or 0%, however, then the likelihood of perceiving illusory motion in the periphery decreases monotonically (Shevell, 2012;Sun, 2011). In the studies here, an increase in feature-binding errors with all-achromatic colorless objects, compared to half red and half green objects as used by Wu et al (2004), would support the hypothesis of overall similarity of single features in the central and peripheral areas because the overall chromatic correspondence among colorless objects (100%) is greater than the 50% correspondence with half red and half green objects.…”

Section: Introductionmentioning

confidence: 99%

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The role of color in motion feature-binding errors

Stepien

Shevell

2015

Journal of Vision

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Color-motion feature-binding errors occur in the periphery when half of the objects are red and move downward, and the other half are green and move upward. When red and green objects in the central visual field are similar but move in the opposite directions (red upward, green downward), peripheral objects often take on the perceived motion direction of the like-colored central objects (Wu, Kanai, & Shimojo, 2004). The present study determined whether color is essential to elicit these motion-binding errors, and tested two hypotheses that attempt to explain them. One hypothesis holds that binding errors occur because peripheral and central objects become linked if they have combinations of features in common. A peripheral object's link to central objects overwhelms its posited weak peripheral representation for motion feature binding, so the peripheral object appears to move in the direction of the linked central objects. Eliminating color by making all stimuli achromatic, therefore, should not increase peripheral binding errors. An alternative hypothesis is that binding errors depend on the overall feature correspondence among central and peripheral features represented at a preconjunctive level. In this case, binding errors may increase when all objects are changed to achromatic because chromatic central/peripheral correspondence is maximal (100%). Experiments showed more motion-binding errors with all-achromatic objects than with half red and half green objects. This and additional findings imply that peripheral motion-binding errors (a) can be elicited without color and (b) depend at least in part on the similarity of central and peripheral features represented preconjunctively.

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Section: Introductioncontrasting

confidence: 80%

Section: Theoretical Implicationssupporting

confidence: 54%

Section: Introductionmentioning

confidence: 99%

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The role of color in motion feature-binding errors

Stepien

Shevell

2015

Journal of Vision

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“…In particular, our study suggests at least three distinct processes adjusting to a change in spectral sensitivity within moments after it occurs. This includes a pronounced anchoring effect from simultaneous contrast [40, 41], which acts to discount the spectral shift almost immediately, and potentially two forms of adaptation that operate over the course of minutes or hours. Both appear to operate at much shorter timescales than the sluggish renormalization observed in cataract patients, and thus suggest the possibility of at least 3 stages of adaptation.…”

Section: Discussionmentioning

confidence: 99%

Adjusting to a sudden “aging” of the lens

Tregillus¹,

Werner²,

Webster³

2016

J. Opt. Soc. Am. A

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Color perception is known to remain largely stable across the lifespan despite the pronounced changes in sensitivity from factors such as the progressive brunescence of the lens. However, the mechanisms and timescales controlling these compensatory adjustments are still poorly understood. In a series of experiments, we tracked adaptation in observers after introducing a sudden change in lens density by having observers wear glasses with yellow filters that approximated the average spectral transmittance of a 70-year-old lens. Individuals were young adults and wore the glasses for 5 days for 8 hours per day while engaged in their normal activities. Achromatic settings were measured on a CRT before and after each daily exposure with the lenses on and off, and were preceded by 5 minutes of dark adaptation to control for short-term chromatic adaptation. During each day, there was a large shift in the white settings consistent with a partial compensation for the added lens density. However, there was little to no evidence of an after-image at the end of each daily session, and participants’ perceptual nulls were roughly aligned with the nulls for short-term chromatic adaptation, suggesting a rapid renormalization when the lenses were removed. The long-term drift was also extinguished by brief exposure to a white adapting field. The results point to distinct timescales and potentially distinct mechanisms compensating for changes in the chromatic sensitivity of the observer.

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“…Thus both adaptation and induction adjust color appearance according to both the mean and variance of the surround (Brown & MacLeod, 1997, Singer & D'Zmura, 1994, Webster, Malkoc, Bilson & Webster, 2002). Both can also adjust to high-level perceptual attributes (Shevell, 2012, Shevell & Kingdom, 2008, Webster, 2011). On the other hand, in the case of lightness and color, spatial context adjustments can include a wealth of phenomena associated with the perceived layout and lighting of scenes and the material properties of objects (Kingdom, 2011).…”

Section: From Temporal To Spatial Contextmentioning

confidence: 99%

Probing the functions of contextual modulation by adapting images rather than observers

Webster

2014

Vision Research

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Countless visual aftereffects have illustrated how visual sensitivity and perception can be biased by adaptation to the recent temporal context. This contextual modulation has been proposed to serve a variety of functions, but the actual benefits of adaptation remain uncertain. We describe an approach we have recently developed for exploring these benefits by adapting images instead of observers, to simulate how images should appear under theoretically optimal states of adaptation. This allows the long-term consequences of adaptation to be evaluated in ways that are difficult to probe by adapting observers, and provides a common framework for understanding how visual coding changes when the environment or the observer changes, or for evaluating how the effects of temporal context depend on different models of visual coding or the adaptation processes. The approach is illustrated for the specific case of adaptation to color, for which the initial neural coding and adaptation processes are relatively well understood, but can in principle be applied to examine the consequences of adaptation for any stimulus dimension. A simple calibration that adjusts each neuron’s sensitivity according to the stimulus level it is exposed to is sufficient to normalize visual coding and generate a host of benefits, from increased efficiency to perceptual constancy to enhanced discrimination. This temporal normalization may also provide an important precursor for the effective operation of contextual mechanisms operating across space or feature dimensions. To the extent that the effects of adaptation can be predicted, images from new environments could be “pre-adapted” to match them to the observer, eliminating the need for observers to adapt.

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The Verriest Lecture: Color lessons from space, time and motion

Cited by 8 publications

References 39 publications

The role of color in motion feature-binding errors

The role of color in motion feature-binding errors

Adjusting to a sudden “aging” of the lens

Probing the functions of contextual modulation by adapting images rather than observers

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