When candidates in primary elections are ideologically differentiated (e.g., conservatives and moderates in the Republican party), then candidates with similar positions affect each others' vote shares more strongly than candidates with different ideological positions. We measure this effect in...

Previous research has shown that opportunities for two-sided partner choice in finitely repeated social dilemma games can promote cooperation through a combination of sorting and opportunistic signaling, with late period defections by selfish players causing an end-game decline. How such...