Orientation anisotropies in visual search revealed by noise

Tavassoli, Abtine and Van Der Linde, Ian and Bovik, Alan C. and Cormack, Lawrence K. (2007) Orientation anisotropies in visual search revealed by noise. Journal of Vision. ISSN 1534-7362

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Abstract

The human visual system is remarkably adept at finding objects of interest in cluttered visual environments, a task termed visual search. Because the human eye is highly foveated, it accomplishes this by making many discrete fixations linked by rapid eye movements called saccades. In such naturalistic tasks, we know very little about how the brain selects saccadic targets (the fixation loci). In this paper, we use a novel technique akin to psychophysical reverse correlation and stimuli that emulate the natural visual environment to measure observers' ability to locate a low-contrast target of unknown orientation. We present three main discoveries. First, we provide strong evidence for saccadic selectivity for spatial frequencies close to the target's central frequency. Second, we demonstrate that observers have distinct, idiosyncratic biases to certain orientations in saccadic programming, although there were no priors imposed on the target's orientation. These orientation biases cover a subset of the near-cardinal (horizontal/vertical) and near-oblique orientations, with orientations near vertical being the most common across observers. Further, these idiosyncratic biases were stable across time. Third, within observers, very similar biases exist for foveal target detection accuracy. These results suggest that saccadic targeting is tuned for known stimulus dimensions (here, spatial frequency) and also has some preference or default tuning for uncertain stimulus dimensions (here, orientation).

Item Type: Journal Article
Additional Information: Citation: Tavassoli, A., Van Der Linde, I., Bovik, A.C. and Cormack, L.K., 2007. Orientation anisotropies in visual search revealed by noise. Journal of Vision, 7(12)..
Faculty: Faculty of Science & Technology
Depositing User: Repository Admin
Date Deposited: 06 Feb 2014 12:36
Last Modified: 07 Jul 2016 12:51
URI: http://arro.anglia.ac.uk/id/eprint/312305

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