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LESSON THREE – ALL YOU NEED TO KNOW EATING BEHAVIOUR Specification link: You will be able to outline and evaluate: Factors influencing attitudes to food and eating behaviour, for example cultural influences, mood, health concerns Outline and description of theory Research evidence and commentary The role of learning Babies are born with taste receptors for sweet, sour, salt, bitter, and umami taste qualities. They can identify and distinguish between different foods from an early age. They like sweet tastes. Benton (2002), found that sweet foods actually reduce distress in babies. This suggests that there may be an innate preference for certain food types which is genetically predisposed. Neophobia is widespread in the animal kingdom as a basic survival mechanism and is found in babies and children. Birch (1999) proposes that we are born with an innate ability to associate food tastes and smells with the consequences of eating that food (rather than an innate food preference). In this way we learn from experience the foods that are good for us and the foods that are not. Parental attitudes and food preferences Parents provide food for the child (usually the mother). Therefore, it is the mother’s attitude to food that affects the child’s preferences. If the mother is concerned over health aspects of food she will ensure that her child has a balanced diet. If the mother is less aware or less concerned about health issues such as obesity, she will take less care over the child’s diet. If early experiences are critical, parental eating habits will profoundly affect their child’s attitudes. Childhood preferences are thought to have a significant effect on adult preferences. However, food preference can be modified by experience and familiarity. Birch and Marlin (1982) found that exposure of twoyear-olds to a new food over six weeks increased preference for that food for that food. A minimum of 8 -10 exposures was necessary to bring about a changed from a dislike to a preference. The children learn that the food is safe. Birch’s proposal that we inherit an ability to make such associations suggests an interaction between nature and nurture. We learn through experience what is good for us (nurture), but that learning depends upon brain circuits that are innate (nature). As expected, there is a significant correlation between the diets of mothers and children (Ogden, 2007) Parents, especially the mother, provide key role models for the child. Nicklaus et al (2004) investigated the correlations between food preferences at age 2 and food preferences at age 22 in a longitudinal study of French children. Although there were only low correlations between overall diet at age 2 and adult diet, for about 50 % of dietary items there was a clear association between childhood and adult preferences especially for cheese and vegetables. Preference for meat decreased in females as they got older, possibly due to ethical and health Page | 1 Peers’ attitudes Once the child reaches school age, peers become important. Media Throughout childhood children are exposed to widespread food advertising on television using peer models, animations etc. to make the food seem more attractive. This can be effective in developing preferences, but unfortunately advertised food tends to be high in fat and carbohydrates probably contributing to problems such as childhood obesity. Mood Food has many other functions besides dietary ones. A key area concerns the emotional aspects of food and feeding behaviour. Studies which investigate the effect of mood and distress on eating often look for evidence of either hypophagia (i.e. excessive undereating) or hyperphagia (excessive overeating), as well as changes in patterns of consumption and food preferences. A sustained decrease or increase in appetite can be an important symptom of depression and other mood disorders (Ogden, 2007) suggests that dieters who overeat in response to low mood may be seeking to mask their negative mood (sometimes referred to as dysphoria) with a temporary heightened mood induced by eating (she calls this the ‘masking hypothesis’). Hunger is associated with increased arousal, vigilance and irritability, while after a meal we feel calm and sleepy and have generally concerns. There were clear links between childhood food preferences and adult diet, but there were also changes, showing that childhood experiences are important, but not the only factors involved. Methodological issues Adult preferences were assessed through questionnaires and Page | 2 interviews which raises the problems of social desirability bias as participants may give ‘healthier answers’ in order to look better in the eyes of the researchers. Lowe, Dowey and Horne, 1998 found that modelling using admired peers can increase consumption of fruit and vegetables. This (along with parents, peers etc) is an example of how social learning theory can be used to explain food preferences. Children observe role models (either in their social environment, peers, teachers, parents etc. or in the media, TV and magazines etc). Due to vicarious reinforcement, they are motivated to imitate this behaviour (could Homer Simpson be a role model?). Advertisements are very powerful in shaping food preferences. Studies have shown that people who are stressed or depressed increase the carbohydrate (especially sugar) and fat content of their meals. Studies indicate that dieters eat more than non-dieters when anxious regardless of the quality of the food (Polivy et al, 1994). pleasurable feelings. Two mechanisms have been proposed to account for this: The serotonin hypothesis: carbohydrates such as chocolate contain the amino acid tryptophan. This is used by the brain in the manufacture of the neurotransmitter serotonin. Low levels of serotonin are associated with depression. It has been proposed that people with stress or depression take in more carbohydrates because it leads to increased levels of serotonin in the brain which reduces their depression (Gibson, 2006). The opiate hypothesis: opiate (or opioid) neurotransmitters such as enkaphlin and betaendorphin are released from neurons and act at synapses with opiate receptors. Opiates (also referred to as endorphins) produce pleasurable feelings and euphoria. It seems likely that the brain’s opiate pathways are part of our reward system, a network of pathways that control our feelings of pleasure and reward. This reward system is activated by natural rewards such as food and drink. Research has found an interaction between opiates and feeding behaviour. Because food is so vital we are very efficient at learning associations between taste and consequences, e.g. taste aversion. This applies to positive effects as well - we learn to associate the mood-improving effects of carbohydrates especially sugars with the sweet taste so when we taste the food, we have expectations about the consequences. Unfortunately, this increase in serotonin levels only occurs when we take in pure carbohydrates, which is extremely rare. The presence of even a small amount of protein, as in chocolate, prevents the tryptophan entering the brain, and so serotonin levels will not changes (Benton, 2002). The serotonin hypothesis is unlikely to explain the antidepressant effects of high carbohydrate diets. Grigson, 2002; Gibson, 2006 found that opiate drugs (e.g. heroin) increase food intake and increase the perceived tastiness of food. Blocking the endorphin system with the drug naloxone reduces food intake, especially sweet foods, and suppresses thoughts about food. This shows that the system is involved in feeding regulation. Sweet foods increase the release of endorphins in the brain. So we feel better after eating sweet carbohydrates as these foods in particular activate our natural reward pathways. This effect would be more obvious in people with depression or with high stress levels, but even in normal circumstances sweet food can improve mood. This applies to physiological systems as well – glucose reliably improves performance on cognitive tasks. However, if people are given a glucose drink but told it is a placebo then the effect disappears. Expectations override the actual intake of glucose. The sweet taste of a glucose solution immediately produces a release of insulin from the pancreas gland, anticipating a rise in blood glucose levels. This happens even with drinks sweetened with saccharine, a compound that is not processed by the body. However, we have learnt that sweet tastes usually mean glucose, so our body prepares itself. Anticipation and expectation on the basis of learning and Page | 3 experience affect our response to it (Gibson, 2006). Culture There are significant differences in diet across cultures. This is often because of the availability of certain foods, e.g. Eskimos live largely on seal meat because that is what is available. Globalisation of the food market means that even in remote communities food choice is increasing – fast food is now available worldwide. However, differences are still found. Leshem (2009) compared Bedouin Arab women living in desert encampments with those now living in urban environments, and also with a group of urban Jewish women. In urban settings, there is access to a far greater range of foodstuffs. The diet of urban Beduoins was very similar to that of desert-living Bedouins, a much higher intake of carbohydrates and proteins and salt than the Jewish group. In a later study, Leshem found that the diet of a Muslim community living in the same urban setting as a Christian group was much higher in carbohydrates, protein and salt than the Christian community, although body mass was the same. Wardle et al, 1997 surveyed the diets of 16,000 young adults across 21 European countries and found that in general the number eating a basic and healthy diet was low, with females doing better than males. There were differences between the countries: People in Meditarranean countries eat more fruit and vegetables than people in England and Scotland People in Scandanavian countries eat the most fibre and people in Portugal, Spain and Italy eat the least. These differences are usually due to availability of particular foodstuffs but also reflect cultural influences. Conclusion Even with equal access to a range of foods, different ethnic groups have different diets, demonstrating the influence of culture and dietary history on food preferences. Page | 4 Previous exam questions January 2011 Discuss the role of one or more factors that influence attitudes to food. (4 marks + 8 marks) Mark scheme AO1 = 4 marks Outline of the role of one or more factors that influence attitudes to food There are many factors shown to influence our attitudes to food. These include innate/evolutionary influences, early learning experience and familiarity, neophobia, parental attitudes, weight concern, cultural factors, the food industry etc. The key to effective answers will be appropriate selection and accurate description of the role of such factors in influencing attitudes to food. Candidates are often tempted to describe brain mechanisms involved in eating behaviour. This can only receive credit in this question part if explicitly linked to the issue of attitudes. Examiners should be sensitive to depth-breadth trade-offs in this question part. AO2/AO3 = 8 marks Commentary on the role of one or more factors that influence attitudes to food For each of the factors mentioned above research studies can provide an effective source of commentary and evaluation on their role in attitudes to food. More general commentary could include the relative role of different factors in, for instance, childhood food preferences, or the change in relevant factors with age. Examiners should be sensitive to the wide range of potential material that would be creditworthy on this question. This includes methodological evaluation of relevant research evidence, analysis and interpretation of data, application and implications and use of scientific findings in society’s decision making (e.g. factors contributing to obesity, the increasing awareness of healthy diets etc). Indicative issues/debates/approaches in the context of the role of one or more factors that influence attitudes to food: approaches – biological/evolutionary, social learning, behavioural, cognitive, psychodynamic: gender and cultural issues, nature/nurture, reductionism, free will/determinism. Such material must be used effectively to move into the top band. Examiners’ report There was a range of answers to this question, varying greatly in quality. Weaker answers were virtually anecdotal, with mention of parents, peers, mood and media influence but with little or no psychological content eg in terms of social learning theory. Better answers explained how these factors, or others, might influence attitudes to food. Research studies were the key to effective commentary, but again some candidates were inclined to provide too much methodological evaluation without bringing out the impact on findings and their implications. Effective IDA included cultural and gender issues, and free will/determinism. Some candidates discussed eating disorders, and these earned credit insofar as they were shaped to the question. Page | 5