Image segmentation and VEP topography

VEP scalp fields were measured for four pattern onset-offset stimuli identical except for the single contrast attribute that allowed a square-wave grating to be seen. The contrast attribute used for each stimulus was either texture, binocular disparity, luminance, or color. All stimuli were presented as dynamic random dot displays. Scalp potentials were sampled at 1.5 cm intervals by 66 electrodes over the posterior scalp. Customized rigid helmets were constructed for each subject to ensure reproducible electrode placement. The scalp fields due to the four stimuli were significantly different in all cross-comparisons. This implies that in the human visual cortex there exists regional selectivity for the processing of the four different contrast attributes.