Understanding the incentives of politicians requires understanding the nature of voting behavior. I conduct a laboratory experiment to investigate whether voters focus on the problem of electoral selection or if they instead focus on electoral sanctioning. If voters are forward-looking but uncertain about politicians’ unobservable characteristics, then it is rational to focus on selection. But doing so undermines democratic accountability because selection renders sanctioning an empty threat. In contrast to rational choice predictions, the experimental results indicate a strong behavioral tendency to use a retrospective voting rule. Additional experiments support the interpretation that retrospective voting is a simple heuristic that voters use to cope with a cognitively difficult inference and decision problem and, in addition, suggest that voters have a preference for accountability. The results pose a challenge for theories of electoral selection and voter learning and suggest new interpretations of empirical studies of economic and retrospective voting.