Figure 1. Example of the stimuli.

(A) is a red symmetric target; (B), a red noise mask; and (C), a compound image in which a red symmetric target (A) is embedded in a red noise mask (B). (D) is a symmetric target composed of red and green dots; (E), a noise mask composed of red and green dots; (F), a compound image in which a red-green symmetric target (D) is embedded in a noise mask of the same colors (E). (G) is a symmetric target composed of red, green, blue and yellow; (H), a noise mask and (I) is a compound image with a symmetric target (G) embedded in a noise mask of the same colors (H).