The sources of the communication gap

Face-to-face communication drastically increases cooperation rates in social dilemmas. We test which factors are the most important drivers of this communication gap. We distinguish three main categories. First, communication may decrease social distance. Second, communication may enable subjects to assess their opponent’s cooperativeness ("type recognition") and condition their own action on that information. Third, communication allows subjects to make promises, which create commitment for subjects who do not want to break a promise. We find that communication increases cooperation by 56 percentage points. Roughly 74% of this effect can be attributed to type recognition, the remaining 26% to a commitment value. We do not find evidence that social distance plays a role.