Figure 5. Visual stimuli (A) and delayed nonmatching-to-sample (DMNS) task (B) used in the present study, and three task phases for an analysis (C).

(A) Sixteen photos of four categories of the stimuli including snakes, monkey faces, monkey hands, and simple geometrical patterns. (B) Stimulus sequence in the DMNS task in which stimuli were sequentially presented with a delay. (C) Three phases during which gamma oscillation was analyzed. Illustrations are original drawings by Q. V. Le and H. Nishijo; snakes were photographed by Mr. I. Hoshino and Mr. D. Hillman.