While 4-year olds provided help when it did not cost them, their inclination to do so was significantly diminished when it incurred a personal cost

The cost of helping: An exploration of compassionate responding in children. Mitchell Green, James N. Kirby, Mark Nielsen. British Journal of Developmental Psychology, https://doi.org/10.1111/bjdp.12252

Abstract: Children engage in prosocial behaviour from an early age. Whether children will reliably provide compassionate help to a suffering individual is unclear. To investigate this, 73 4‐years‐olds were presented with three novel tasks in which they and a puppet had opportunity to win stickers by completing respective versions of the same tasks. In all cases, the puppets were unable to complete their tasks. The puppets ‘reacted’ by being either upset or not upset. While children provided help when it did not cost them, their inclination to do so was significantly diminished when it incurred a personal cost.