Human Food Rejections

Doctoral thesis by Henry Potts


This thesis covers human food rejections in non-clinical situations.

Section 1 considers the list heuristic: a list of foods, with individuals answering some sort of question(s) about each food. The number of foods which elicit a particular response gives a measure of eating behaviour, usually 'pickiness'. Lists were used with a sample of 72 men and another of 116 women. Results concur with previous studies in showing an inverse relationship between pickiness and sensation-seeking; but differ as a relationship with anxiety is not apparent.

Section 2 uses the method of Rozin & Fallon (1980) to consider multiple facets of rejection behaviour. Past work suggests a division of rejection behaviour into 'distaste'/'disgust'/'danger'. Results from 43 subjects replicate the tripartite division and suggest a further substructure among 'distaste' items.

Section 3 covers the nature of the aversion in Learned Food Aversions (LFAs) whereby a food followed by nausea is subsequently avoided. LFAs are important for our understanding of learning behaviours and have clinical implications as a cause of cancer anorexia and possibly other learned nausea phenomena, like anticipatory nausea and vomiting in chemotherapy. The orthodoxy is that LFAs produce a hedonic shift in palatability. Anecdotal reports suggest there is a learned nausea: the target food becomes nauseating.

Previous human experiments have shown that LFAs can be produced, but have not asked about the nature of the aversion. In two experiments, subjects tasted a novel food and then had nausea induced by motion sickness or underwent a control procedure. Their reaction to the target food was later assessed. The first experiment failed to produce any aversion. The second, involving 47 subjects, did and there was a significant change in ratings of how nauseating the target food was in those subjects who had been made nauseous previously, demonstrating a learned nausea.

Title page

Section 0 Introduction

Section 1 The List Heuristic
    1.0 Introduction
    1.1 The Problem: Learning About Food Rejections
    1.2 Methodological Approaches
    1.3 Neophobia
    1.4 Literature Review
        1.4.1 Methods of Earlier Studies
        1.4.2 Psychometric Measures
        1.4.3 Relationships with Other Variables
    1.5 Two New Studies
        1.5.1 South Bank Sample
        1.5.2 Family Diet Study Sample
        1.6 A Synthesis?

Section 2 Food Rejection Taxonomy
    2.0 Introduction
    2.1 The Need for a Taxonomy
    2.2 The Method of Rozin & Fallon (1980)
    2.3 The Importance of Nausea
    2.4 Methodology
        2.4.1 The Food Rejection Indices and its Design
        2.4.2 Procedure
    2.5 Basic Results
        2.5.1 Description of Subjects
        2.5.2 Results: FRIs
    2.6 Multidimensional Scaling Results
        2.6.1 Preliminary Data Processing
        2.6.2 Overall Solution
        2.6.3 Bootstrapping
    2.7 Prototypes for the Four Rejection Categories
        2.7.1 'Distaste'
        2.7.2 'Disgust'
        2.7.3 'Danger'
        2.7.4 'Inappropriate'
        2.7.5 Conclusion
    2.8 Neophobia
        2.8.1 MDS Results (see statistics project )
        2.8.2 Suggested Ethology
        2.8.3 Relationship with Anxiety
    2.9 Food scaresóBSE and Salmonella(see Potts, 1994 )
        2.9.1 Introduction
   History and Description of BSE
   History and Description of Salmonella
   Comparison Between BSE and Salmonella
        2.9.2 'Danger' or 'disgust'?
        2.9.3 Uncertainty
        2.10 Unusual Variants
            2.10.1 Sullivan & Birch (1990)
            2.10.2 Results
            2.10.3 Suggested Ethology (see Potts, 1993 )
        2.11 Smoking
            2.11.1 MDS Results
            2.11.2 Use of FRI in a Different Context
        2.12 Conclusion

Section 3 Learned Food Aversions
    3.0 Introduction
    3.1 Literature Review
        3.1.1 Experimental Psychology
        3.1.2 Clinical (Human) Phenomena
   Emetic Aversion Therapy
   Anticipatory Nausea and Vomiting (ANV)
   "Cancer Anorexia"
    3.2 The Nature of the Response Produced
        3.2.1 Literature Review
    3.3 Clinical Perspectives
    3.4 Methodological Issues to do with Nausea in Humans
        3.4.1 Generating Nausea in an Ethically Acceptable Way
        3.4.2 Measurement of Nausea
    3.5 Two Studies
        3.5.1 Study 1
       Symptom Ratings
       Responses to Kúrrta
        3.5.2 Study 2
       Symptom Ratings
       Responses to Kúrrta
       Physiological Measures
    3.6 Conclusion

Section 4 Conclusion

Section 5 Appendices
        5.1.1 Food Lists
        5.1.2 Anglicized Version of the Food Neophobia Scale
        5.1.3 Modern Equivalents for 'Neuroses' in the Early List Heuristic Studies
        5.2.1 Example FRI
        5.2.2 FRI Items Chosen by Subjects
   'Distaste' Items
   'Disgust' Items
        5.2.3 FRI Results in Full
        5.3.1 Modified Cincinnati Neophobia Scale
        5.3.2 Electrogastrography

Section 6 References

Section 1 has been published in an abridged form as Potts & Wardle (1998). The second study in Section 3 (3.5.2) was presented at conference: Potts, Wardle & Gresty (1997). Small parts of Section 2 have also been presented at conference: 2.10.3 as Potts (1993) and 2.9 as Potts (1994). In addition, Potts (1995) also used the data collected in Section 2, but its content is not included in this thesis.

The data collected in Section 2 were used as example data in a thesis submitted in partial fulfillment of an MSc in Applied Statistics (Potts, 1996). Potts (1996) developed the statistical procedures subsequently used in 2.6.3 seq., although the analyses presented here are new to this work. Material from both theses has been used for a later presentation (Potts, 1998).

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Last updated: 19 Jan 2004