Researchers and lay people alike have long held an interest in understanding the antecedents, mechanisms, and consequences of prosocial behaviours: Acts people behave in ways that benefit others, such as cooperation, altruism, care-giving, empathy, sympathy, and compassion. Numerous lines of inquiry have now documented that acting prosocially carries many benefits for not only the recipient, but also the actor. For instance, acting prosocially attracts social capital, social support, and boosts interpersonal relationships; prosociality also increases one’s well-being, happiness, and has long-term physical and mental health benefits. While much of the past work has focused on the main effects of prosociality on various positive outcomes, one area that has received limited attention is understanding the contextual factors and individual differences that moderate these relationships. In the present thesis, I focus on understanding how socioeconomic status (SES) acts as a moderator of the link between prosociality and numerous positive outcomes. In particular, I examined how prosociality is related to building social networks through weak ties, coping with daily stress, and building interpersonal skills. Across these relationships, I examined how SES moderates the link between prosociality and each outcome.

My research was guided by the SES-prosociality paradox: That while the rich have access to far greater resources – and thus the ability to act prosocially – it is the poor that tend to act most generously. I theorized that one reason for this paradox is that people across different SES strata benefit differently from acting prosocially. In particular, I reasoned that the people from lower SES backgrounds will tend to have stronger relationship between prosociality and various positive outcomes than people from higher SES backgrounds.

To test this hypothesis, I conducted numerous empirical studies using multiple methods – analysing data from subjective reports via surveys and existing data from social media, running natural experiments, and conducting lab experiments using genetic and pharmacological challenge methods. In Chapters 2 and 3, I found that people who act prosocially tend to attract more weak social ties – this is only true for the relatively poor. In Chapter 4, I tested how empathic traits relate to better coping strategies for both lower and higher SES individuals, and found a complex pattern of differing benefits. Finally, in Chapter 5, I found that intranasal oxytocin improves emotional theory of mind, but only for the low SES individuals.