People prefer to diversify across different types of prosocial behaviour.

People have multiple opportunities to act prosocial any given day but only limited resources to do so (e.g. time, effort and money they are willing to invest). We test whether people prefer to diversify their prosocial efforts across different types of help: casual help, direct help, indirect help and emotional support. In two daily diary studies (total N = 711), we examine whether previous prosocial behaviour affects subsequent prosocial behaviour for the same or other types of prosocial behaviour. We found that day-to-day prosocial behaviours reflected a diversified helping pattern. Participants were less likely to help the same way (i.e. the same type of prosocial behaviour) on subsequent days and more likely to help in different ways (i.e. a different type of prosocial behaviour). This tendency did not extend to casual help in Study 2, implying that the next day reduction in doing the same type of prosocial behaviour is limited to prosocial behaviours that are at least somewhat effortful or time consuming.