Guillaume Dezecache, Laurence Conty, Michele Chadwick, Leonor Philip, Robert Soussignan, Dan Sperber, Julie Grèzes (2013) Evidence for unintentional emotional contagion beyond dyads. PLOS One 8(6), e67371

Abstract: Little is known about the spread of emotions beyond dyads. Yet, it is of importance for explaining the emergence of crowd behaviors. Here, we experimentally addressed whether emotional homogeneity within a crowd might result from a cascade of local emotional transmissions where the perception of another’s emotional expression produces, in the observer’s face and body, sufficient information to allow for the transmission of the emotion to a third party. … [Our] findings demonstrate that one is tuned to react to others’ emotional signals and to unintentionally produce subtle but sufficient emotional cues to induce emotional states in others…