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Abstract:
The detection of visual targets against their background is critical for shape perception. The human lateral occipital complex (LOC) has been implicated in the processing of shapes. We tested whether the LOC processes information about the context (background) of shapes. We addressed this question by using event-related fMRI adaptation in which lower neural responses are observed for two identical than for two different consecutively presented stimuli. The stimuli consisted of displays with a closed target contour of collinear Gabor elements embedded into a background of randomly oriented Gabors. There were four different conditions: (i) identical image, where the two stimuli in a trial were the same; (ii) different shape, where the target shape was different; (iii) different context, where the target shape was the same but the background was different; (iv) completely different, where both the target shape and the background were different. We observed adaptation in the LOC when the target shapes were presented in the same background, but no adaptation when they were presented in different backgrounds. These findings suggest that neural populations in the LOC process information about the context of visual shapes.
