Attentional narrowing describes how attention shrinks as arousal increases. A moderate narrowing can be helpful — it filters out irrelevant distractions and focuses you on the task. But when arousal climbs too high under pressure, attention narrows excessively, and athletes begin to miss relevant cues and options they would normally perceive.
A point guard under intense pressure might miss the open teammate they'd usually spot; a quarterback might lock onto one receiver and miss the field; a tennis player might lose awareness of court positioning. The information is there, but the over-narrowed attention can't take it in.
This phenomenon is one reason arousal regulation matters so much: keeping arousal in the optimal zone preserves an appropriately wide field of attention. It also relates to choking, since excessive narrowing is one way pressure degrades performance. Training attentional control — including the ability to shift between broad and narrow focus on demand — helps athletes counteract unwanted narrowing.