In this thesis, I have considered a number of aspects of human food rejection behaviour. Section 1 considered personality correlates of pickiness, a tendency to reject food items. Section 2 sought to confirm and explore a tripartite taxonomy of food rejection forms. Finally, Section 3 focused on one particular food rejection response, the Learned Food Aversion (LFA), and the precise nature of the aversion produced. As often in psychology, methodologies designed to answer simple problems throw up more questions. Methodological approaches in all three sections posed their own issues.
In Section 1, a psychometric approach to human food rejections, through the list heuristic or specially designed indices like the FNS, gave inconclusive results. The samples presented here and in past work are somewhat discordant. The reason for differing results is unclear. Are there methodological differences undetected by the approach taken in this thesis that lead different questionnaires to measure rather different things; or are there important societal differences between the populations studied here and previously? The one consistent explanatory variable of interpersonal differences is the inverse relationship between pickiness and sensation-seeking.
This section does suggest that neophobia is very important to most everyday food rejection choices, although in retrospect this is unsurprising given how we define ‘food’. More consistent studies replicated in various populations around the world would be useful, but my main conclusion is that the list heuristic is more complicated than one at first would imagine and that it may be too simple an approach, confounding a range of disparate behaviours.
Section 2 recognises the need to consider the nature of food rejections and an important place to start is in constructing a taxonomy. Rozin & Fallon’s (1980) tripartite division—‘distaste’, ‘disgust’ and ‘danger’—has proven to be sound, but there is also some evidence for a more complex pattern.
The principle of asking multiple questions about the different aspects of a food rejection is worthwhile, but methodologies remain too arbitrary in design. Do variations in the questions asked about each food rejection matter and can they be chosen in a more systematic way?
Dissemination of the taxonomy and its application in other areas is now required. Pliner & Pelchat’s (1991) discovery that neophobia towards animal-based foods involves ‘disgust’ is an important result, replicated here. On the other hand, no results were forthcoming to suggest that a similar role exists for ‘disgust’ in certain food scares (BSE and Salmonella).
Work in Section 3 proves the value of the ideas of the previous section. We do see a learned nausea response in LFAs, despite the assumption that a hedonic shift in palatability underlies LFAs in most of the literature. That result has considerable implications as it changes our perception of a learning archetype and supports relationships with certain clinical phenomena. This work also illustrates the importance of selecting appropriate animal models (rats cannot vomit) and for interdisciplinary communication.
Where should research on LFAs go next? At a practical level, we need to consider the extinction of LFAs in order to be able to treat idiosyncratic LFAs, cancer anorexia and ANV. More generally, there needs to be a transfer of knowledge from theoretical work into a clinical setting.
Food rejection behaviour is multi-faceted. Food rejections can be divided into three categories, ‘distaste’, ‘disgust’ and ‘danger’, and the first of these may warrant further subdivision.
The rejection produced in a learned food aversion (LFA) involves a learned nausea. This suggests there may be important links to other learned nausea phenomena.