Attention

Attention is the brain's triage mechanism for sensory and cognitive input, deciding in real time which signals get routed to conscious processing and which get filtered out before reaching working memory. It is a finite resource allocated based on perceived relevance: material the brain tags as personally meaningful gets through, material that doesn't is dropped before encoding can begin. Attention is the first gate in the learning pipeline and the constraint that governs how much of a session ever enters the participant's memory in the first place.