Greater than the sum of their parts? When combinations of institutions improve citizens’ decisions

Many scholars show that institutions help citizens with their political decisions. However, real-world contexts contain multiple institutions that are imposed together. Thus, I develop a theory and experimental test of the conditions under which combinations of two institutions induce citizens to trust a speaker’s statements and make better decisions than when only one institution is present. The theoretical model demonstrates that a second institution typically should not alter a speaker’s propensity to make truthful statements, nor subjects’ decisions to trust those statements. The experimental results reveal important departures from such rational behavior. Specifically, a second institution makes subjects more willing to trust the already mostly truthful statements they receive, which enables them to make better decisions than when only one institution is imposed upon the speaker. These findings suggest lessons about the conditions under which institutions can increase trust and improve decision making in political, legal, and economic contexts.