Statistical analysis.

Two-way between-subjects ANOVAs were performed to test for any main effects and interactions of luminance and contrast on BOLD response (experiments 1 and 2), as well as contrast-condition slope measurements and voxelwise median slope measurements (experiment 2 only). The median slope measurement was calculated for each distribution of voxelwise contrast-condition slope estimates across luminance and contrast conditions in experiment 2. Circular statistics (angular mean and Rayleigh z test) were performed using the CircStat MATLAB toolbox (Berens 2009) to investigate any topographic organization of luminance-based responses. A one-way ANOVA was performed to test for any systematic differences in functional signal-to-noise (SNR) measurements across visual area ROIs for both experiments 1 and 2.