Caffeine reinforces flavor preference and behavior in moderate users but not in low caffeine users

The study examined the role of caffeine consumption in caffeine reinforcement. Previous findings have shown that caffeine reinforced flavor preference in moderate caffeine consumers who are caffeine deprived. However, most of these studies have employed rating procedures only, and have not shown the effectiveness of caffeine to reinforce behaviors other than through subjective ratings. Twenty-five participants (15 low caffeine consumers, and 10 moderate caffeine consumers) were each given three exposures to a caffeinated drink, and three exposures to a non-caffeinated drink. Each drink was associated with a particular color. At each session, they were asked to rate the pleasantness of the drink, and choose from distinctively colored sweets. The results showed an increase in the rating of pleasantness for the caffeinated drink in moderate caffeine consumers, but a decrease in rated pleasantness for low caffeine consumers. The opposite effect was seen for the non-caffeinated drink. There was an increase in consumption of the number of sweets with the same color as that of the caffeine-paired drink in the moderate caffeine consumers. These findings suggest that caffeine may serve as a negative reinforcer, and that the alleviation of withdrawal symptoms may be associated with the flavor and appearance of the caffeinated drink.