Adaptation is a decrease in or change in sensitivity to a given stimulus as a result of continued exposure to that stimulus or a similar one. In sensory testing, this effect is an important unwanted source of variability of thresholds and intensity ratings.
In the following example of "cross-adaptation" (O'Mahony 1986), the observer in con dition B is likely to perceive Jess sweetness in the test sample because the tasting of sucrose reduces his sensitivity to sweetness: