Fourteen Japanese undergraduate and gradu- ate students living in the Kanto region of Japan, 7 females and 7 males with an average age of 21.1 years (SD = 0.91) participated in this experiment. They were unaware of the experimental purpose, and were paid. Each participant had normal or corrected-to- normal visual acuity, and passed the Ishihara Color Test to screen out achromatopsy