Dezecache G., Conty L., Philip L., Chadwick M., Soussignan R., Sperber D. & Grèzes J. (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…