When Does Increasing Mobilization Effort Increase Turnout? Evidence from a Field Experiment on Reminder Calls

When does increasing mobilization effort increase turnout? Recent experiments find second calls containing a reminder to vote increase turnout beyond an initial contact. We argue existing studies cannot explain why reminder calls are effective because they test bundled treatments including a late mobilization attempt, a late mobilization attempt given earlier contact, and potentially activating reciprocity established in earlier contact. We report results from a two-round voter mobilization field experiment that allows us to isolate these different mechanisms. We find that reminder calls increase turnout by 1.2% points among subjects contacted in an earlier attempt, but that enhancing reciprocity by providing a reminder call offer during an early call does not increase turnout beyond a second call. Additionally, we fail to find heterogeneous effects of reminder calls by stated preference for a reminder or by stated vote intention, suggesting certain mechanisms do not explain the effects of reminder calls.