 This study examined how different background colors can affect the gender categorization of faces. When shown upright, a red background tended to lead to more females being identified than those seen on a green or gray background. However, when the same faces were inverted, the red background had no effect on the number of males identified. This suggests that the red background may have been influencing the participant's decisions based on their prior knowledge of the color's association with feminine qualities. This article was authored by NHN, Koyonokamura, and Katsumi Watanabe.