Sharing emotions with other individuals is a widespread phenomenon. Previous research proposed that experiencing intense and similar emotions with other individuals reinforces social bonds. However, several aspects of this phenomenon remain unclear, notably whether social bonding requires the convergence and synchronization of emotions in the group, and whether these effects generalize across positively valenced and negatively valenced emotional contexts. To address these questions, we measured subjective emotional experiences, physiological activity (cardiac, respiratory, electrodermal) and social attitudes in dyads of unacquainted individuals who watched videos in the presence of each other. We manipulated the emotional content of the videos and the type of shared attention between participants, to test for the contribution of interpersonal influence. The results revealed that intense emotions indexed by physiological arousal were associated with the emergence of reciprocal prosocial attitudes within dyads, and that this effect depended on joint attention. We did not observe the convergence and synchronization of emotions within dyads, which suggests that experiencing similar emotions was not necessary for social bonding. We discuss implications of this study for research on collective effervescence and the social consequences of shared experiences.