This paper proposes a model to explain the differences between outcomes of referenda and the voting trends suggested by polls. Two main effects are at stake. First, the evolution of the voters' attitudes is conditional on the public information made available to them. Second, the predisposition towards abstention among individuals within each voting group may be different. Our model describes how these two aspects of decision making may interact, showing how public available information may amplify the distinct tendency towards abstention between both groups and thus affect the outcome of the referendum.