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What is white?

Version 2 2023-06-12, 06:36
Version 1 2023-06-08, 22:44
journal contribution
posted on 2023-06-12, 06:36 authored by Jenny BostenJenny Bosten, R D Beer, D I A MacLeod
To shed light on the perceptual basis of the color white, we measured settings of unique white in a dark surround. We find that settings reliably show more variability in an oblique (blue-yellow) direction in color space than along the cardinal axes of the cone-opponent mechanisms. This is against the idea that white perception arises at the null point of the cone-opponent mechanisms, but one alternative possibility is that it occurs through calibration to the visual environment. We found that the locus of maximum variability in settings lies close to the locus of natural daylights, suggesting that variability may result from uncertainty about the color of the illuminant. We tested this by manipulating uncertainty. First, we altered the extent to which the task was absolute (requiring knowledge of the illumination), or relative. We found no clear effect of this factor on the reduction in sensitivity in the blue-yellow direction. Second, we provided a white surround as a cue to the illumination, or left the surround dark. Sensitivity was selectively worse in the blue-yellow direction when the surround was black than when it was white. Our results can be functionally related to the statistics of natural images, where a greater blue-yellow dispersion is characteristic of both reflectances (where anisotropy is weak) and illuminants (where it is very pronounced). Mechanistically, the results could suggest a neural signal responsive to deviations from the blue-yellow locus, or an adaptively matched range of contrast response functions for signals that encode different directions in color space.

History

Publication status

  • Published

File Version

  • Published version

Journal

Journal of Vision

ISSN

1534-7362

Publisher

Association for Research in Vision and Ophthalmology (ARVO)

Issue

16

Volume

15

Page range

1-19

Article number

a5

Department affiliated with

  • Psychology Publications

Full text available

  • No

Peer reviewed?

  • Yes

Legacy Posted Date

2015-10-08

First Compliant Deposit (FCD) Date

2015-10-08

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