Extrinsic information influences taste and flavor perception: a review from psychological and neuroimaging perspectives.

The perception of taste and flavor can be greatly biased by extrinsic cues, or the information about a food that comes from outside of the food itself, such as package designs, brands, prices, and so on. In order to understand taste/flavor experiences in a broader context, it is necessary to consider factors other than the food/tastants themselves. This review aims to summarize some of the relevant findings from psychological and neuroimaging studies, focusing on depicting how extrinsic cues exert their effect on taste and flavor. Currently, the most frequently considered psychological mediator for the effects of extrinsic cues is expectation. Depending on the gap between expectation and taste/flavor experience, four major models predict outcomes of expectation effects: (1) assimilation, (2) generalized-negativity, (3) contrast, and (4) assimilation-contrast. Among them, the most influential is the assimilation model proposing that taste/flavor experiences are modified toward what one expects. Thus far, all the neuroimaging studies examining the influence of extrinsic cues have dealt with assimilation effects. They suggest that when extrinsic cues influence taste/flavor perception, cortical representations of taste/flavor are also modulated. Collectively neuroimaging findings partly answer questions arising from psychological aspects: the influence of extrinsic cues is not due to superficial response bias but to truly changed perception. These findings, albeit limited to assimilation effects, suggest that combined understanding from both psychological and neuroimaging studies would help deepen our understanding of the taste experience.