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Published November 2006 | Published
Journal Article Open

The relation of phase noise and luminance contrast to overt attention in complex visual stimuli

Abstract

Models of attention are typically based on difference maps in low-level features but neglect higher order stimulus structure. To what extent does higher order statistics affect human attention in natural stimuli? We recorded eye movements while observers viewed unmodified and modified images of natural scenes. Modifications included contrast modulations (resulting in changes to first- and second-order statistics), as well as the addition of noise to the Fourier phase (resulting in changes to higher order statistics). We have the following findings: (1) Subjects' interpretation of a stimulus as a "natural" depiction of an outdoor scene depends on higher order statistics in a highly nonlinear, categorical fashion. (2) Confirming previous findings, contrast is elevated at fixated locations for a variety of stimulus categories. In addition, we find that the size of this elevation depends on higher order statistics and reduces with increasing phase noise. (3) Global modulations of contrast bias eye position toward high contrasts, consistent with a linear effect of contrast on fixation probability. This bias is independent of phase noise. (4) Small patches of locally decreased contrast repel eye position less than large patches of the same aggregate area, irrespective of phase noise. Our findings provide evidence that deviations from surrounding statistics, rather than contrast per se, underlie the well-established relation of contrast to fixation.

Additional Information

©2006 AVRO. Received September 2, 2005. Revision received September 5, 2006. Published October 9, 2006. This work was supported by the Swiss National Science Foundation (W.E., Grant Nos. PBEZ2-107367 and PA00A-111447), NIMH, NGA, NSF, and Caltech's "SURF" program. We thank A. Acik and H.-P. Frey for technical assistance and C. Quigley for editorial assistance.

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September 14, 2023
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