May 2008
Volume 8, Issue 6
Vision Sciences Society Annual Meeting Abstract  |   May 2008
Selectivity for multiple orientations in visual search
Author Affiliations
  • Abtine Tavassoli
    Department of Electrical and Computer Engineering, University of Texas at Austin, USA
  • Ian van der Linde
    Department of Computing, Anglia Ruskin University, UK
  • Alan Bovik
    Department of Electrical and Computer Engineering, University of Texas at Austin, USA
  • Lawrence Cormack
    Department of Psychology, University of Texas at Austin, USA
Journal of Vision May 2008, Vol.8, 1078. doi:
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      Abtine Tavassoli, Ian van der Linde, Alan Bovik, Lawrence Cormack; Selectivity for multiple orientations in visual search. Journal of Vision 2008;8(6):1078.

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

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Observer strategies in visual search for targets containing multiple orientations were considered in the study. We used our efficient search framework (Tavassoli et al., 2007), a reverse-correlation based technique distinguishing between non-foveal and foveal processes, to examine how observers search for low-contrast targets created from sums (Experiment 1) and mosaics (Experiment 2) of Gabors. Eye movements were recorded while observers searched for one target randomly embedded in one tile of a grid of 1/f noise tiles. Fixated noise-only tiles (non-foveal false alarms) and a subset of these noise tiles selected by the observer as target candidate (foveal false alarm category) were analyzed off-line. We present several key findings. First, we show a strong presence of visual guidance in saccadic targeting in search for our composite targets, demonstrated by selectivity for spatial frequencies and (in some cases) orientations close to the characteristics of each target. Second, we show that, in most cases, the multiple orientations composing the targets were represented in both saccadic programming and target selection, but were not always equally weighted. Third, different mosaic configurations produced different tunings in orientation, but visibly idiosyncratic to each observer (Experiment 2). A local spectral analysis on sub-regions of noise tiles was performed to examine the use of phase. Fourth, a curious presence of close-to-vertical structures is observed in the results, although the search targets did not contain vertically-oriented structures (Experiment 2).

Tavassoli, A. van der Linde, I. Bovik, A. Cormack, L. (2008). Selectivity for multiple orientations in visual search [Abstract]. Journal of Vision, 8(6):1078, 1078a,, doi:10.1167/8.6.1078. [CrossRef]
 This research was funded by NSF grants ECS-022545 and ITR-0427372.

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