Abstract
Aim: Contour-shape processing is selective to motion direction [Gheorghiu, Kingdom & Varshney, 2010, Journal of Vision, 10(3):18, 1-19), and surround textures prevent the shape of a contour from being processed as a contour but instead as part of a texture, a phenomenon we term here ‘texture-surround capture of contour-shape’ [Gheorghiu & Kingdom, 2011, Journal of Vision 11(11), 1038; Kingdom & Prins, 2009, Neuroreport, 20(1), 5-8]. This raises the question as to whether the effect of texture surrounds on contour shape processing is selective to motion direction and temporal frequency. Methods: Subjects adapted to pairs of sinusoidal-shaped textures or to single contours that differed in shape-frequency, and the resulting shifts in the apparent shape-frequency of single-contour test pairs was measured. The texture adaptors consisted of a central contour, and a non-overlapping surround made of a series of contours arranged in parallel. Contours drifted within a fixed stimulus window in one or other direction of their axis of shape modulation. We varied (i) motion direction and (ii) the temporal frequencies of both central contour and texture surround. Results: We found that (i) the shape after-effect was strongly reduced by surround textures moving in the same but not opposite directions to the central contour; (ii) the reduction in shape after-effect caused by the surround texture increased in magnitude with the temporal frequency of the central contour, and (iii) the reduction in shape after-effect was selective for same center-surround temporal frequency. Conclusion: Texture-surround capture of contour shape is tuned to both motion direction and temporal frequency.
Meeting abstract presented at VSS 2012