Final answer:
Mario's act of giving Eric money for lunch and Eric's subsequent feeling of owing Mario a favor is an example of the reciprocity norm, which is the expected give and take in relationships.
Step-by-step explanation:
Mario giving his friend Eric money for lunch and Eric feeling that he owes Mario a favor is an example of the reciprocity norm. This concept describes the unspoken agreement where there is an expectation of the exchange of favors or services among individuals. Not to be confused with the social-responsibility norm, which is the expectation that people will help those in need without expecting something in return, or social exchange theory, which suggests individuals engage in relationships by weighing the costs and benefits. Generalized reciprocity is more commonly found among close relationships like families and good friends, where assistance is provided without the immediate expectation of repayment, but over time it may balance out. The feeling that one should respond in kind to someone else's actions is deeply rooted in social interactions and can be seen cross-culturally, as mentioned in Confucius' teachings.