Research on pedestrian dynamics has generally dealt with temporary gatherings of people who do not know each other personally. These gatherings are often framed as highly individualized encounters in which social interactions play no or only a marginal role. However, recent research based on self-categorization theory showed the relevance of salient social identity for crowd dynamics. Drawing on the interactionist approach of social identity theory and the work of Erving Goffman and Alfred Schütz, this paper aims to show that anonymous encounters are carefully concerted social phenomena. The authors present the results of an exploratory social psychological experiment (N= 83), in which groups of participants were asked to wait for 5 min in a designated area with different communicative conditions and then to walk to a narrow exit. Based on the assumption that communication and conformity to expectations influences the behaviour of those present, we introduced four modifications during the waiting time and analysed questionnaire data and video recordings in a mixed-methods design. The results show that direct communication correlates with higher speed, cell phone use with greater distance to the nearest neighbour, and unexpected behaviour with slower movement.