The experimental literature on social dilemmas has long documented the positive effect of communication on cooperation. Sally (1995), in a meta-analysis spanning thirty-five years of Prisoner's Dilemma experiments, shows that the possibility of communicating significantly increases cooperation. Social psychologists have explained such a finding by hypothesizing that the act of communicating contributes to promoting trust by creating empathy among participants (see Loomis (1959), Desforges et al. (1991), Davis and Perkowitz (1979)). Bicchieri (2002, 2006), in a different perspective, puts forward a focusing function of communication hypothesis, according to which communication can focus agents on shared rules of behavior and – when it does focus them on pro-social ones – generates a normative environment which is conducive to cooperation. More specifically, when individuals face an unfamiliar situation, they need cues to understand how best to act and, for this reason, they check whether some behavioral rule they are aware of applies to the specific interaction. The effect of communication is to make a behavioral rule situationally salient, that is, communication causes a shift in an individual's focus towards the strategies dictated by the now-salient rule. In doing so, communication also coordinates players' mutual expectations about which strategies will be chosen by the parties. In other words, (under some conditions) communication elicits social norms.
While a large proportion of studies on the effect of pre-play communication focuses on Prisoner's Dilemma games, Bicchieri, Lev-On, and Chavez (2010) examine behavior in sequential trust games. In what follows we shall look at those findings, discuss an interpretation based on the above hypothesis, and suggest a theoretical application that can account for it. Given that our analysis equally applies to the Prisoner's Dilemma, this essay contributes to the broad literature on social dilemmas by proposing an application for dynamic interactions.
Bicchieri (2002) provides the basis for the focusing function of communication argument: when a rule of behavior becomes situationally salient, it causes a shift in an individual's focus, thereby generating empirical and normative expectations that direct one's actions.