June 2017
Volume 17, Issue 7
Open Access
OSA Fall Vision Meeting Abstract  |   June 2017
Individual differences in lightness judgments explained by variable spatial extents of contextual influence
Journal of Vision June 2017, Vol.17, 45. doi:10.1167/17.7.45
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      Michael E. Rudd; Individual differences in lightness judgments explained by variable spatial extents of contextual influence. Journal of Vision 2017;17(7):45. doi: 10.1167/17.7.45.

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      © ARVO (1962-2015); The Authors (2016-present)

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In simple disk-annulus lightness displays, assimilation can influence the disk lightness over one range of annulus luminances, while contrast influences it over another range of annulus luminances (Rudd, 2010). To account for this pattern, I proposed a computational lightness model involving three neural processing stages: i) encoding of local oriented edge contrast; ii) contrast gain control between neurons responding to nearby edges; and iii) spatial integration of oriented contrast to compute lightness (Rudd, 2014, 2016). Previous experiments demonstrated that a luminance edge can be voluntarily included in this computation—or not—depending on the observer's interpretation of the edge as a reflectance edge or an illumination edge (Rudd, 2010). Here I present evidence for a second, distinct, type of top-down influence that controls the size of the spatial window over which spatial context influences the disk lightness. To explain quantitative lightness matching data with my model, the first type of top-down influence (edge classification) must occur early (i.e. pre-contrast gain control), while the second type (window size) must occur late (i.e. post-contrast gain control).

Meeting abstract presented at the 2016 OSA Fall Vision Meeting

Rudd, M. E. 2010. How attention and contrast gain control interact to regulate lightness contrast and assimilation Journal of Vision 10(14): 40– doi:10.1167/10.14.40 [CrossRef] [PubMed]
Rudd, M. E. 2014. A cortical edge-integration model of object-based lightness computation that explains effects of spatial context and individual differences Frontiers in Human Neuroscience 8640– 1–14 doi:10.3389/fnhum.2014.00640 [CrossRef] [PubMed]
Rudd, M. E 2016. Retinex-like computations in human lightness perception and their possible realization in visual cortexProceedings of the Imaging Science and Technology International Symposium on Electronic Imaging2016

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