The sexual overperception bias is a tendency for men to over-infer the sexual intent of women. Studies have documented the existence of this bias and explained it in terms of socialization, decreased thresholds of sexual intent perception, detection of nonverbal cues, and as an adaptation that increases reproductive success. Since missed sexual opportunities incur a heavy cost upon a man’s reproductive success, we propose that the sexual overperception bias evolved due to the greater cost of under-perceiving rather than over-perceiving a woman’s sexual intent (Haselton, 2003). A vignette method will be used to analyze the context-specificity of this bias. We will test the reproducibility of findings that this bias is blocked when evaluating the sexual intent of individuals that do not present viable sexual opportunities, such as opposite-sex siblings. Further, we will control for limitations in previous research, such as effects of familiarity, by evaluating perceptions of sexual intention on the part of opposite-sex friends in addition to opposite-sex siblings.