No evidence for latent learning of liking for flavours conditioned by caffeine

Abstract

Rationale: The ability of caffeine to condition liking for flavours depends on the caffeine deprivation status of subjects; however, it is not known if a latent liking for a flavour can be acquired in an undeprived state, which subsequently emerges when consumers are caffeine deprived.

Objectives: To determine if exposure of undeprived caffeine consumers to a novel drink containing caffeine leads to increased liking for this drink when they are subsequently tested when caffeine-deprived.

Methods: In a double-blind placebo controlled study, four groups of 13 moderate caffeine consumers evaluated a novel flavoured drink on 5 days. The test group consumed this drink with 100 mg caffeine when undeprived on days 1-4, and in a deprived state on day 5. Three control groups had the same conditions on all 5 days, with an undeprived group receiving the caffeinated drink, and two deprived groups receiving the drink with caffeine or placebo.

Results: The pleasantness of the drink did not change over the 4 training days in the test group, and did not alter when this group was tested when caffeine-deprived. At no stage did these ratings differ between the test and undeprived control groups. Pleasantness increased significantly over the 5 days in the deprived group who received caffeine, and decreased in the deprived group who received placebo.

Conclusions: These results suggest that repeated pairing of a novel flavour with the effects of caffeine in subjects who are not caffeine deprived does not lead to an emergent liking for that flavour when subsequently tested caffeine-deprived. However, the pleasantness of the same caffeinated drink increased if it was consumed when caffeine deprived.