Fig. 1.

Visual stimulation. (Top) Stimuli used (upright, inverted, and scrambled faces). (Bottom) Illustration of one cycle of visual presentation with upright faces. Stimuli were presented dynamically with sinusoidal contrast modulation (0 to 100%) at a rate of 0.8 Hz (1 cycle = 1.25 s), overlapped onto a weakly contrasted background. Stimuli of the same type were presented continuously in blocks of 40 cycles (50 s) or until the subject stopped fixating.