Disaggregating deliberation's effects: an experiment within a deliberative poll

Using data from a randomized field experiment within a Deliberative Poll, we examine deliberation’s effects on both policy attitudes and the extent to which ordinal rankings of policy options approach single-peakedness (a help in avoiding cyclical majorities). The issues were airport expansion and revenue-sharing in New Haven, Connecticut and its surrounding towns. Half the participants deliberated revenue-sharing, then the airport, the other half the reverse. This split-half design enables us to distinguish the effects of the formal on-site deliberations from those of other aspects of the Deliberative Polling treatment. We find that the formal on-site deliberations accounted for much of the Deliberative Polling effect on one issue, though not the other—thus both confirming deliberation’s capacity to shape attitudes and preferences and raising the question of how its effects may depend on the kind of issue being deliberated. We suggest that deliberation’s effects are larger for less salient issues.