Abstract
Shape adaptation studies have suggested that contour-shape and texture-shape are processed by different mechanisms and surround-textures inhibit the processing of the shape of contours (Gheorghiu, Kingdom & Petkov, 2014). Here we examine the event-related potential (ERP) signature and time-course of neural processes involved in coding the shape of contours and textures before and after adaptation to assimilations and segregations of contours into or from surround textures. Stimuli were contours made of strings of Gabors oriented parallel to the path of the contour or textures made of a series of contours arranged in parallel. Texture-surround adaptors consisted of a central contour flanked by a surround made of parallel contours those Gabors orientations were either parallel or orthogonal to the path of the contours. Participants adapted to either pairs of sinusoidal-shaped textures or single contours that differed in shape frequency and the resulting shift in the apparent shape-frequencies of texture-test and contour-test pairs were measured together with the ERP responses from posterior brain regions. We found that (a) in the absence of adaptation, the negative amplitude of the ERP response peaked at around 150 ms for texture-tests and 225 ms for contour-tests. For post-adaptation: (b) contour-tests produced similar ERPs following adaptation to different types of adaptors from around 100 ms but with the ERP amplitude being more negative for single contour-adaptors than parallel and orthogonal texture-surrounds; (c) ERP responses to texture-tests were also dependent on the adaptor type, with amplitudes being larger when the adaptor was a contour than a texture. We conclude that the ERP responses to contour-tests and texture-tests are differentially modulated by contour and texture-adaptors. While ERP response to contour-tests is slightly modulated by both contours and surround-textures, the ERP response to texture-tests is only modulated by contour-adaptors.
Meeting abstract presented at VSS 2018