Distaste is a primitive rejection impulse triggered by the ingestion of unpleasant tasting substances, many of which are toxic. Theoretical work has suggested that distaste may be the evolutionary precursor for both physical disgust, which serves to defend against disease and other threats to biological fitness, and moral disgust, which defends against threats to the social order. Consistent with this proposal, recent work has found that the facial expression of distaste may be similar to that of disgust. Specifically, raising of the upper lip has been reported in distaste, physical disgust, and moral disgust. However, competing evidence suggests that distaste and disgust expressions may differ, and the facial expressions of adult humans in response to distasteful stimuli remain poorly specified. To address this issue, we conducted a preliminary experiment to investigate the upper lip raise in adult volunteers (N = 15) as they tasted unpleasant, pleasant, and neutral liquids. We found increased raising of the upper lip for bitter and salty tastes relative to water and sweet, suggesting that the upper lip raise is indeed part of the distaste expression. Given evidence that the upper lip raise is also present in physical and moral disgust, these results are consistent with the proposed origins of disgust in distaste.
Keywords: disgust; distaste; emotion; facial expression; taste.
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