Increases in prosociality across adulthood: The pure-altruism hypothesis.

A growing body of research suggests that prosocial behavior increases across adulthood. Yet, whether these age differences reflect "pure altruistic" or selfish motives, or the developmental mechanisms that underlie them, are largely unknown. Within a value-based decision framework, pure altruistic tendencies can be measured and distinguished from impure altruistic motives through neural-level information. Indeed, age differences in donations appear to be driven by a genuine concern for the well-being of others. Candidate mechanisms behind such pure altruistic changes need to show documented age differences and evidence of causal links to prosocial behavior. As examples, we discuss how three factors that meet these criteria--social norms, mood, and cognitive functioning--might explain age differences in pure altruistic tendencies.