Wealth or generosity? People choose partners based on whichever is more variable

Organisms benefit from choosing partners who are willing and able to provide them with benefits (e.g., choose based on warmth, competence, wealth). But which should they prefer in a partner – willingness or abilities? We tested the hypothesis that people will focus on whichever trait is more variable in others: the more variance there is in a trait, the greater the difference there is between the “best” and “worst”, so the more that trait will impact the chooser (all else equal). In two studies, participants saw a range of partners for a hypothetical money distribution task who either varied more in the amount of money they had to distribute (Unequal Wealth condition) or in the percent of their money they gave away (Unequal Generosity condition). Participants had a default preference to know about others' generosity rather than their wealth; this preference was strengthened when others varied more in generosity and weakened when others varied more in wealth. Thus, our study shows that people are sensitive to the amount of population variance on a trait, and flexibly adjust their partner preferences to focus on traits which vary more among others.