Acquisition and extinction of flavour preferences conditioned by caffeine in humans

Previous research has shown that moderate caffeine users develop a liking f or the flavour of a novel caffeinated drink only if they experience this dr ink in a caffeine-deprived state. This study tested how sensitive these con ditioned-flavour preferences are to subsequent changes in deprivation state and the continued presence or absence of caffeine. Thirty-six moderate caf feine consumers were given 4 training days during which they evaluated a no vel flavoured caffeinated drink consumed mid-morning after 12 h caffeine de privation. Subjects were then divided into four groups depending on whether or not they remained caffeine-deprived and whether the test drink continue d to contain caffeine. They then re-evaluated the novel drink over a furthe r 4 test days. As expected, liking for the test drink increased across the 4 training days, and this increased liking was maintained across the 4 test days in the up who continued to receive the caffeinated version of the dri nk in a caffeine-deprived stare. Liking decreased in test phase in the caff eine-deprived group who no longer received caffeine (extinction). It is sur prising that both groups who were tested in a non-deprived state showed a m arked decrease in liking on all 4 test days relative to the last training d ay. This implies that conditioned-flavour preferences may not be expressed in the absence of the relevant motivational state (caffeine deprivation). T ogether, these data suggest that flavour preferences conditioned by caffein e are very sensitive to changes in the contingent relationship between depr ivation state and caffeine content of the drink. (C) 2000 Academic Press.