What is second-order vision for? Discriminating illumination versus material changes


The human visual system is sensitive to second-order modulations of the local contrast (CM) or amplitude (AM) of a carrier signal. Second-order cues are detected independently of first-order luminance signals; however, it is not clear why vision should benet from second-order sensitivity. Analysis of the first-and second-order contents of natural images suggests that these cues tend to occur together, but their phase relationship varies. We have shown that in-phase combinations of LM and AM are perceived as a shaded corrugated surface whereas the anti-phase combination can be seen as corrugated when presented alone or as a flat material change when presented in a plaid containing the in-phase cue. We now extend these findings using new stimulus types and a novel haptic matching task. We also introduce a computational model based on initially separate first-and second-order channels that are combined within orientation and subsequently across orientation to produce a shading signal. Contrast gain control allows the LM + AM cue to suppress responses to the LM-AM when presented in a plaid. Thus, the model sees LM -AM as flat in these circumstances. We conclude that second-order vision plays a key role in disambiguating the origin of luminance changes within an image. © ARVO.

Publication DOI: https://doi.org/10.1167/10.9.2
Divisions: College of Health & Life Sciences > School of Optometry > Optometry
College of Health & Life Sciences
Additional Information: Creative Commons Attribution Non-Commercial No Derivatives License
Uncontrolled Keywords: 3D surface and shape perception,computational modeling,shading,spatial vision,Ophthalmology,Sensory Systems
Publication ISSN: 1534-7362
Last Modified: 16 Jul 2024 07:03
Date Deposited: 23 Apr 2012 11:29
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Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
http://www.jour ... 10/9/2.abstract (Publisher URL)
PURE Output Type: Article
Published Date: 2010-07-16
Authors: Schofield, Andrew (ORCID Profile 0000-0002-0589-4678)
Rock, Paul B.
Sun, Peng
Jiang, Xiaoyue
Georgeson, Mark A. (ORCID Profile 0000-0002-8173-9522)

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