Leaving a bad taste

Some emotion researchers suggest there are only a very small number of universal emotions: fear, anger, happiness, sadness, surprise, and disgust (see Taste Topics, October, 2013: Feeling all emotional). All other emotion terms, in this view, reflect these basic emotions. But even if you are inclined to believe that there are dozens, if not hundreds, of distinct emotional states, there remains one common indivisible emotion, disgust. Disgust sits alone in the cathedral of emotions, shunned even by dislike, guilty and worried. When talking about emotions elicited by foods, the uniqueness of disgust is rather …. unique, in that it is the only emotion that specifically implies a relationship to our sense of taste.

But, of course, foods are not supposed to disgust us, and fortunately most of us seldom come across examples of foods that do. Moreover, although our potential experience and express disgust is innate, we need to learn what things should make us disgusted. It is a familiar enough scenario where a mother mimics the classic disgust face to a child about to eat something they have picked up from a footpath. With just a wrinkle of the nose, a baring of the upper teeth and a gaping mouth (and perhaps a “Yuk!”), the mother teaches the child a lesson about the potential dangers of otherwise edible items contaminated by …. who knows what, but certainly something that might cause disease. This common sense view is generally supported too by theoretical accounts of the evolutionary purpose of such a strong emotion which stress its role as disease-prevention mechanism [1].

Indeed, we could argue that disgust – despite the origins of the word – has little to do with taste or foods per se. Paul Rozin has characterized disgust as the emotional aspect of fear of contamination through, in the case of foods, consumption. Hence, food is just one of those things that we stick in out mouths that could potentially cause us harm via contamination. It is easy to show that food likes and dislikes show an inconsistent relationship to disgust. So, foods that are highly unpleasant, for example by being bitter, do not necessarily, or even often, induce feelings of disgust.  And, of course, it is possible for us to recognize that foods from other cultures could potentially taste great and be full of important nutrients, even if the idea of them caused a distinct shuddering of the spine.

We can see an illustration of this in the recent enthusiasm for insects as potential food sources in the future. A small, but growing, movement is examining how best to take advantage of the nutrients that insects can provide, and considering how best to deal with consumer responses to this [2]. Because of this interest, which is strong in Denmark, I was recently treated to a lunch provided by the Nordic Food Lab, in which the menu contained a dish labeled “Peas and Bees”. The label was perfectly descriptive, and I managed to overcome my urge to say “thank you, I’m already full”. Those expecting little yellow and black highlights against the green background would have been disappointed, however, as only bee larvae were used.

Disgust doesn’t always require extreme foods or obvious contamination. Perfectly clean, everyday foods in perfectly clean bedpans will do it, as will being offered a glass of water into which a plastic model of a cockroach has been briefly dipped. In an earlier posting, I noted the extreme reactions to a choc-mint flavoured potato crisp (Taste Topics, November, 2013: Colour me .... minty). In many respects, this response to violation of expectations is a co-opting of so-called core disgust (that is, associated with ingestion of a potential contaminant) to cover a situation in which the unpredictability of the flavour could be a signal for possible danger.

A broadening of the disgust emotion to include those situations where contamination in the physical sense is not a risk is also evident. We talk, for example, about being disgusted by violence or by someone’s behavior or their appearance or their table manners. At least some of these reactions can be included under the term moral disgust. Rozin [3] suggests that the disgust emotion began life as an extension of our in-built responses to bitterness to which we added a cognitive appraisal of other (whether bitter or not) substances that we did not want to consume. This allows us to learn what to be disgusted by as a function of culture or violated expectations. Similarly, strong violations of beliefs, values or rules have become ‘attached’ to disgust. While we might just be using disgust as a metaphor in such situations, there is evidence that it is something more fundamental. Thus, in the same way that the classic disgust facial expression shares common features with facial expressions to unpalatably bitter foods, it can be shown that both core disgust and the moral disgust at being treated unfairly in a game activate a very similar set of facial muscles [4]. So, at least the expression of disgust appears to be highly similar.

A later study looked at associations between bitterness sensitivity, reflected in PROP taster status (Taste Topics, May, 2013: Supertaste me!), and different questionnaire scales of disgust sensitivity [5]. By distinguishing between different types of disgust: visceral (related to disease, bodily fluids and sexual activity) and moral, the study was able to show that those most sensitive to the bitterness of PROP (supertasters) were also significantly more sensitive to visceral disgust - that is, involving the possibility of contamination through ingestion or otherwise - but not moral disgust. It is possible therefore that the link between core disgust and moral disgust is merely semantic or metaphorical. An alternative explanation, however, is that (as suggested above) that across the two stages or jumps from bitterness responses to core disgust to moral disgust, the link between taste reactivity and moral disgust is weakened or lost.

In either case, examining the origins of moral disgust provides further opportunities to consider the possibility – raised in the previous two postings – that the source of many of our more complex emotional or personality traits can be found in quite fundamental early taste experiences.
1. Oaten, M.J., R.J. Stevenson, and T.I. Case, Disgust as a Disease-Avoidance Mechanism. PSYCHOL. BULL., 2009. 135(2): p. 303-321.
2. Verbeke, W., Profiling consumers who are ready to adopt insects as a meat substitute in a Western society. Food Qual Pref, 2015. 39: p. 147-155.
3. Rozin, P., From Oral to Moral. Science, 2009. 323: p. 1179-1180.
4. Chapman, H.A., et al., In Bad Taste: Evidence for the Oral Origins of Moral Disgust. Science, 2009. 323: p. 1222-1226.
5. Herz, R.S., PROP Taste Sensitivity is Related to Visceral but Not Moral Disgust. Chem. Percept., 2011. 4: p. 72-79.