Social categorization is the foundation of stereotype activation, and the process from social categorization to stereotype activation is rapid. However, the time from social categorization to stereotype activation is unknown. This study involves a real-time measurement of the time course of gender-stereotype activation beginning with gender categorization using event-related potential technology with a face as the priming stimulus. We found that 195 ms after a face stimulus was presented, brain waves stimulated by male or female gender categori...