Fig. 4

a Time–frequency map of averaged Stereo-VEP at Oz electrode upon visual stimuli with various disparities. Upper row in from left to right: TF-Analysis images upon stimuli with ‘S1’ (2D image) and ‘S2’ (3D image with both uncrossed and crossed disparities); Bottom row from left to right: TF-Analysis image upon stimuli with ‘S3’ (3D image with large crossed disparity) and ‘S4’ (3D image with large uncrossed disparity); b dominant frequency distributions of VEPs at P270 under stimulation with four different types of disparities