Political deliberation is the exchange of opinions and information that takes place among citizens with similar or different viewpoints. In contemporary democracies, this process has mostly occurred through three important mechanisms of political intermediation: interpersonal discussion, diverse exposure to media information, and new mechanisms of deliberation in Internet and social media (Twitter, Facebook, and more). Contributions on this area of political behavior and political psychology have increased exponentially during the last decade and a half, but they also present important limitations and contradictory findings.