Most decisions in daily life are not made alone but together with others, requiring us to determine when to trust another person's judgment over our own. To do so, we can use the other's confidence as a helpful indicator of accuracy. While verbal communication about confidence has indeed been shown to enhance collective decision accuracy, little is known about whether and how confidence can be transmitted nonverbally—through the observation of others' movements. In this study, we investigate how confidence information conveyed via movement shapes real-time social decision dynamics. Specifically, we test whether two individuals infer confidence information from each other's movements and then use this information to achieve a collective benefit in perceptual decision-making. Our results show that (1) dyads make better perceptual decisions than individuals, (2) confidence information is 'encoded' in movement patterns, and (3) individuals infer and use this information to guide their collective decisions. Moreover, our experimentally inspired modeling demonstrates that integrating a partner's encoded confidence with one's own improves collective decision accuracy compared to when the partner's confidence is not considered. These findings highlight the importance of bodily motion for the social transmission of confidence information in collective decision-making.