Dynamic social impact in electronic juries: The emergence of subgroup clustering through small group communication

Testing a new theory of dynamic social influence, 39 mock juries in two studies deliberated student honor court cases by electronic mail. After reading about each case, participants sent and received messages to a spatially coherent or random subset of jurors on each of five sessions. Individuals appeared to take their role of juror seriously and were responsive to each others' arguments; one-third changed their verdicts after receiving two out of two opposing messages and just over half changed in the face of four of four opposing messages. Polarization toward the majority verdict was common in both studies; however, consistent with a key prediction of dynamic social impact theory, unanimity was suppressed among the spatial compared to random juries by the emergence of spatially distinct subgroups. Clustering and polarization were prevalent even among juries passing as few as two messages per juror each round, providing strong evidence that DSIT applies even to important issues.