Stereotypes contribute to performance differences as negative stereotypes can be perceived as threatening, like the threat of being judged negatively or inadvertently confirming the stereotypes. When stereotypes are made salient, the stereotyped groups perform worse in many academic and non-academic domains. The primary goal of this study was to determine which cognitive processes underlie Stereotype Threat. 307 men and 305 women were asked to complete a series of trials, either a mean estimation task or an emotion recognition task. Half of the group was told that we were interested in their perceptual abilities. The other half was informed that we are testing their mathematical abilities or emotion recognition skills and that we were interested in gender differences. Additionally, they were asked to indicate their gender before performing the task. The manipulation in the second group revealed differences in reaction times but not in accuracy for women in mathematical tasks in the Stereotype Threat condition. A diffusion model analysis revealed higher thresholds for women in the Stereotype Threat condition but no substantial differences in drift rate. The results suggest that more liberal decision criteria and more cautions response patterns are induced by Stereotype Threat. The lack of difference in drift rates indicates no changes in working memory capacity, as many previous studies have suggested. This is an important step in explaining Stereotype Threat and preventing the impact of negative stereotypes on marginalized groups.