Prosocial acts-those that are costly to ourselves but benefit others-are a central component of human coexistence(1-3). While the financial and moral costs of prosocial behaviours are well understood(4-6), everyday prosocial acts do not typically come at such costs. Instead, they require effort. Here, using computational modelling of an effort-based task, we show that people are prosocially apathetic. They are less willing to choose to initiate highly effortful acts that benefit others compared with those benefitting themselves. Moreover, even when choosing to initiate effortful prosocial acts, people exhibit superficiality, exerting less force into the actions that benefit others than those that benefit themselves. These findings were replicated, and were present whether the other person was anonymous or not, and when choices were made to earn rewards or avoid losses. Importantly, the least prosocially motivated people had higher subclinical levels of psychopathy and social apathy. Thus, although people sometimes 'help out', they are less willing to benefit others and are sometimes 'superficially prosocial', which may characterize everyday prosociality and its disruption in social disorders.