. the presence of other bystanders ??? ??? ??? According to the text, the _______ of altruism propose(s) two types of prosocial behavior: a tit-for-tat reciprocal exchange and a more unconditional, intrinsic helpfulness. social norms, social-exchange, and evolutionary theories ??? ??? ??? The motive to increase another's welfare without conscious regard for one's self-interests defines altruism ??