title: The dependence of visual scanning performance on search direction and difficulty.
abstract: Phillips and Edelman [Phillips, M. H., & Edelman, J. A. (2008). The dependence of visual scanning performance on saccade, fixation, and perceptual metrics. Vision Research, 48(7), 926-936] presented evidence that performance variability in a visual scanning task depends on oculomotor variables related to saccade amplitude rather than fixation duration, and that saccade-related metrics reflects perceptual span. Here, we extend these results by showing that even for extremely difficult searches trial-to-trial performance variability still depends on saccade-related metrics and not fixation duration. We also show that scanning speed is faster for horizontal than for vertical searches, and that these differences derive again from differences in saccade-based metrics and not from differences in fixation duration. We find perceptual span to be larger for horizontal than vertical searches, and approximately symmetric about the line of gaze.
authors.affiliation: Department of Biology, The City College of New York, Convent Avenue at 138th Street, New York, NY 10031, USA. mp2570@columbia.edu
authors.forename: Matthew H
authors.initials: MH
authors.lastname: Phillips
authors.forename: Jay A
authors.initials: JA
authors.lastname: Edelman
mesh_terms: D001288:Attention / Q000502:physiology; D005403:Fixation, Ocular / Q000502:physiology; D006801:Humans; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011597:Psychomotor Performance / Q000502:physiology; D012438:Saccades / Q000502:physiology*; D013997:Time Factors