A wine tasted twentieth is not judged on the same terms as a wine tasted second. Receptor adaptation and palate residue make sequence a real variable rather than a formality.
Receptors adapt to sustained input
Sensory systems respond to change rather than to absolute levels, and prolonged exposure to a stimulus steadily reduces the response to it. The effect is automatic and cannot be overridden by concentration.
After several tannic reds in succession, the drying sensation registers less strongly, and a genuinely astringent wine can seem moderate. The wine has not changed; the reference point has.
The same adaptation happens with acidity and with oak-derived aromatics. A palate recalibrates towards whatever it has been shown repeatedly, and judges the next glass against that adjusted baseline.
Residue carries forward between glasses
Tannin binds to proteins in the mouth and takes time to clear, so a heavily tannic wine measurably affects the one that follows it. Two or three glasses may pass before the mouth is genuinely neutral again.
Sweetness carries over even more persistently, which is why anything sweet sits at the end of a sequence. A dry wine tasted after a sweet one reads as thin and unripe.
Strongly oaked wines leave aromatic residue in the nose and throat that the next glass must overcome before it can be assessed fairly. Unoaked wines suffer most from being placed immediately afterwards.
The conventional order and its logic
The standard progression runs sparkling, light whites, fuller whites, light reds, structured reds and finally sweet wines.
Each step moves towards greater intensity, so no wine is asked to follow something that overwhelms it. The sequence protects the delicate rather than flattering the powerful.
Where a tasting focuses on one style, the order usually runs youngest to oldest, since older wines are more easily buried by primary fruit.
How competitions try to correct for it
Structured panels break flights into small groups with breaks between them, because fatigue accumulates within a flight far faster than across a day.
Wines are also re-tasted in a different order where scores diverge, which separates genuine disagreement from sequence effects.
Water and plain bread between flights are not ceremonial. They physically remove residue and give receptors a period without stimulus.
What this means for the amateur taster
A domestic tasting of more than eight or nine wines produces increasingly unreliable notes towards the end, regardless of how attentive the taster is.
Revisiting the first wines at the close is the cheapest correction available, and the gap between the two readings is often startling.
Writing notes as each wine is poured rather than at the end preserves the impression before the palate has moved on from it.