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Laura Renninger, Preeti Verghese; Orientation discrimination in the periphery depends on the context. Journal of Vision 2007;7(9):585. doi: 10.1167/7.9.585.
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© ARVO (1962-2015); The Authors (2016-present)
PURPOSE How the visual system processes complex contours in a scene is still largely unknown. We seek to better understand the interaction of discrete orientations in the periphery during contour processing. As a first step, we examine how the orientation of a target line element is perceived as a function of surrounding orientation information. METHODS A target line was presented briefly in the periphery and observers were asked to judge its orientation from one of eight possible orientations, in steps of 22.5deg. The target element was surrounded by a half circle of oriented lines with different organizations: randomly oriented (random), tangent to the half circle (co-circular) and normal to the half circle (sun ray). The distance between the target and surround was varied. In the control condition, no surround was present. RESULTS The influence of the surround on target judgment depended on the distance between target and surround and began to affect performance at a distance of 1/10 the eccentricity. Orientation labeling of the target was impeded most when the surround was disorganized (random) and improved when the surround was organized (co-circular and sun ray). Errors in the organized conditions were restricted to neighboring orientations (22.5deg) while errors in the random condition were distributed to non-neighboring orientations. CONCLUSIONS The judgment of an orientation target is easiest if the surround is organized. When the surround is disorganized, the target orientation is more difficult to label and observers are more prone to guessing. The crowding literature demonstrates that the content of the surround is important for target perception. In this work, we've shown that the organization of that content is also important.
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