persistence

Whether a change survives the thing that made it — whether a gain measured today still stands tomorrow, or quietly sinks back toward where it began.

A trait shift at 6 months is not a trait shift at 14 months, and neither is a trait shift for life. Persistence is the question that turns a state into a trait: a chemical that lifts openness while it is in the body may produce a gain that decays when the drug leaves; a mystical experience that restructures the self-model may produce a gain that endures without maintenance. The hard part is that persistence is always measured at a specific follow-up point, and "persisted at 14 months" is not "persisted forever" — the window between measurement and permanence is where the consolidation's possible value lives, untested.