Play
Play is behavior that is self-motivated, intrinsically rewarding, and structurally distinct from functional behavior directed at immediate survival goals. It is most conspicuous in young mammals but persists throughout the lifespan in various forms.
In the active inference framework, play is understood as safe exploration: the agent engages with the world in contexts where the pragmatic costs of failure are low, allowing the epistemic value term to dominate. Play reduces expected free energy not by achieving practical goals but by refining the generative model in low-stakes environments.
This explains why play is most prevalent in juveniles: the pragmatic costs of exploration are lowest when parental care buffers survival risks. It also explains why adult play persists in forms that maintain low stakes: games, arts, intellectual puzzles, and social banter all provide epistemic value without pragmatic risk.