The current thesis investigates the operational sex ratio of the environment and its effects on people’s accuracy in evaluating the sex and commitment intent of others. We conducted a speed meeting experiment in Ihsan Doğramacı Bilkent University’s Psychology Laboratory (N=260), where both men and women evaluated their partner’s sexual intent towards them. Results showed a difference between sexes in the error types they made when they evaluated sexual intent. We did not observe any effect of operational sex ratio between experimental groups. We discuss possible reasons for the absence of this effect and directions for future research.