Who's in an In-Group? Experimental Evidence from Regionalism in Mexico

Who we act pro-socially towards and want to redistribute to is at the heart of many economic and political questions, and a key piece is to understand who individuals consider is in their in-group. Through two complementary experiments on charitable giving, one with Mexican students and one in supermarkets across Mexico, I study how primes interact with group attachment to determine whether a subject's in-group includes the whole nation or a smaller region. The in-group includes the whole nation if subjects are attached more to the nation or if the nation is primed—otherwise the in-group only includes a smaller region. Those more attached to the region widen their in-group with the prime, but their in-group generosity diminishes. Thus, priming a broad group results in its members getting the watered-down pro-sociality of those attached to a smaller group