Give users realistic primary tasks while controlled posture changes occur in the HUD. Observe whether they notice the right changes, ignore low-priority updates appropriately, and preserve their original task context after an interruption. Ask them to explain each indicator's meaning, source, and required response. Include color-vision differences, keyboard navigation, assistive technology, small screens, long labels, and simultaneous updates.
Useful measures can include detection of material conditions, false interruption rate, time to resume the primary task, correct identification of owner, and number of unnecessary view changes. Guardrails include alert fatigue, habitual dismissal, action from the wrong scope, inaccessible status changes, and persistent exposure of sensitive context. Results describe the tested roles and scenarios, not a universal productivity or safety improvement.