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AQA A2 Psychology Eating Behaviour

Terms in this set (25)

Evolutionary explanations of food preferences
Evolutionary theory proposes the idea that there is genetic variability within humans, just as there is in any animal species. By the process of natural selection, those possessing genes best suited for the environmental conditions they live in, will allow them to survive, reproduce and pass on this genes to their offspring. Such examples may include, better at finding food sources, better at reproducing quickly. It sees that the eating behaviour of humans begun developing in the Pleistocene era, a time of nomadic hunter-gatherers who lived in small, tightly knit, closely-related groups facing battle everyday to find enough food to survive. This era ended when food begun to be cultivated through agricultural practices and methods of detecting toxic food were being introduced. These preferences are still apparent today; we originally seeked to eat as much calorie-rich food as possible and store it as fat for when there were periods of famine, now food scarcity is not a problem, our diets aren't developing to eliminate the calories we do not need.
Sweet taste preferences
Sweetness was associated with high-energy and non-toxic content that aided survival. Desor et al and Steiner both found that neonates prefer sweet foods to bitter ones, by evaluating their facial expressions. Implying that there preference is innate. To support this, Logue found that humans have specific receptors on our tongues for detecting sweetness, other tastes have non-specific receptors and there are far fewer of them.
Although Desor et al and Steiner found an evolutionary link between sweet tasting foods and human beings, the interpretation of neonates' facial expressions is somewhat subjective and may not produce reliable results, this weakens the evolutionary link.

However, Steffanson reported that Copper Inuits were disgusted at their first taste of sugar and thus these findings go against the notion of sweetness being a universal preference.
Salty taste preferences
Salt is necessary for the body to function properly, being essential for maintaining neural and muscular activity and water balance. Salt deprivation can cause intense cravings causing animals to travel great distances in the hopes of discovering salt deposits.
Beauchamp found those with a sodium deficiency have an innate response to ingest salt and find it more palatable in order to regulate its balance within the human body, an adaptation that has evolved in order for humans to survive. Yet salt now causes problems as we consume too much, without being aware of it. The EEA argues that food companies exploit our evolutionary inheritance and causing serious health implications in the long-term. We now have the inability to control or salt intake by our diet, this intake is predetermined for us and social factors now have much more of a greater influence than our evolved characteristics.
Bitter and sour taste preferences
The ability to detect these tastes makes evolutionary sense as bitter tastes indicate the presence of toxins, this explains why humans possess around 30 genes that code for bitter taste receptors in order to avoid these foods and therefore survive.
Go et al looked at the prevalence of the bitter taste receptor T2R in humans to test for an evolutionary ability to detect bitter tastes. It was found that humans had accumulated more dead genes than other primates and so suggesting that our tasting capability deteriorates more rapidly, which is why species to species food preferences differ so widely. As our environment intercepts with innate adaptations natural selection is acting to reduce humans' ability to detect and stay away from bitter tastes, even though, some are in fact beneficial for our survival. To prevent this, a practical application is the use of sweetened medicines for children so that the bitter, yet valuable medicine can be ingested and swallowed .
Meat taste preferences
The advantage of being able to digest meat it beneficial to humans' survival. Rich in fat and thus high in energy, available all year round to have an advantage over seasonal plant foods. But Dunn shows that humans did not begin as carnivores as our dental structures and digestive systems are more similar to herbivores than carnivores, suggesting that consuming plants is more natural for human bodies and that humans do not have an innate preference for meat. On the other hand, Foley and Lee found meat eating led directly to an increase in human intelligence to suggest that meat eating was indeed evolutionarily favoured.
General evolution AO2/3/IDA
It is difficult to come to a conclusion upon whether evolution was to work in our favour or whether we worked against it since much research into this area is controversial. The basic evolutionary idea is that we should eat foods that aid survival and reproduction, and avoid those that do not, however in modern day society we do not need to depend greatly and solely on food for survival, we have medical care for example and thus overwriting our evolutionary instincts to fit in with modern day scenarios. This helps to explain the binge-eating phenomena observed in some humans today that eventually leads to obesity as we no longer face the threat of food scarcity, yet we continue to eat calorie-rich food anyway. Evolutionary drives are moderated and modified by social drives leaving the question of whether it is nature that is more important, or if it is nurture.
Neural mechanisms in eating behaviour
The biological model focuses on hunger, satiety and the role of neuro-chemicals in determining when and how much we eat. Hunger is regarded as a motivation to eat whilst satiety is the opposite, the feeling of fullness which activates us to stop eating, this is similar to the way in which we control glucose levels in homeostasis, via negative feedback. It revolves around the idea that each person has a set point and our weight is regulated around this, thus, if we feel hungry, we increase food intake, when we feel full food intake will decrease and a balance will be restored once again.
The Lateral Hypothalamus
Early studies proposed that the hypothalamus was central to food intake. The medial hypothalamus is the 'satiety centre' and the lateral hypothalamus being the 'feeding centre'. But more recently other brain regions have been closely linked to feeding; the paraventricular hypothalamus and the perfornical area.
A neurotransmitter in the hypothalamus called neuropeptide Y was found to be particularly important in turning on eating, when this was injected into mice it made them begin eating even if they were already satiated (Wickens) and resulted in obesity over just a few days (Stanley et al.). This however, is not an accurate representation of normal brain functioning as such behaviour was only caused by excessive amounts of artificially injected NPY. In humans, Yang et al has shown that NPY is also produced by abdominal fat which creates a vicious cycle of eating, making more fat cells and thus releasing more NPY. By treating individuals using drugs that turn off the production of NPY will obesity is prevented.
The Ventromedial Hypothalamus
Researchers discovered that damage to our 'satiety centre' caused rats to overeat, this is called hyperphagia and so concluded this under normal conditions it works to inhibit feeding. Contradictory evidence from Gold, who found that animals with VMH lesions ate substantially more and gained substantially more weight than those with lesions to other areas of the brain for example, the paraventricular nucleus. Yet those with lesions in other areas also overate, but not to the same extent. This suggests that perhaps the VHM does not have such a large role as we first thought in inducing a feeling of satiety and that more research must be carried out in order to justify the idea of the VMH being the sole 'satiety centre'.
IDA/Ethics
However an ethical issue is that nearly all of this research is conducted on animals such as rats. We cannot assume that the rules found in rats can be applied to humans as well so we can't be certain this link between the hypothalamus and eating behaviour exists in humans as well thus the research findings must be generalised with caution.
To focus solely on neural mechanisms as responsible for eating behaviour is deterministic, as it disregards the element of free will that individuals have over their eating behaviour.
Factors influencing attitudes to food and eating behaviour
As humans we have evolved to make sure that we take in the right nutrients in order for our body to function efficiently, but if more food is put in than is needed or expelled, it is converted into fat stores. There are many factors that influence our attitudes towards food and eating, like mood, cultural influences, health concerns and socio-economic factors that interact with our innate sources to shape our eating behaviour.
Mood
Depending on our individual differences, some find that when they are stressed, they tend to eat more 'comfort food' yet others do not feel the need to eat. Tice et al found that participants responded to distress by eating more fattening, unhealthy snacks and Wansink et al offered popcorn and grapes to participants, those watching a sad film were found to eat more popcorn to cheer themselves up whereas those watching a comedy ate the grapes in order to prolong their mood.
Evaluation
Although this evidence does support the notion that people consume more when they are stressed, it does not identify the relative influences of acute and chronic stress some people undergo at certain points in their life, thus evidence is limited and low in ecological validity and can only be applied to mildly stressful situations rather than life-changing circumstances.
Culture
Cultural practices vary world-wide, such as families eating together, eating pancakes on Shrove Tuesday, poor income and so a poor quality diet and the restriction of certain foods such as pork. Lawrance et al noted that in collectivist non-western cultures females learned their cooking skills from their mothers and grandmas and took time to prepare family meals. As opposed to the Western society where food is based around a short preparation time and the desire to be thin. Underneath all this, all women valued healthy eating, but did not necessarily practise it due to other factors, availability, cost and time that differ across the world.
With the increase in world population mobility, developments in transport systems and modern food hygiene practices such as refrigeration eating behaviour are becoming for global and less based on individual cultural locations. Since we now have greenhouse technology to create certain controlled environments for growing plants out of their season so that they can be available all year round.
Health Concerns
Education plays a role, as higher-level education is associated with increased health awareness and health-based behaviour that ultimately creates the desire to eat and life a healthy lifestyle. De Almeida et al found that information disseminated from a source such as a school, was perceived as trustworthy, and the information provided was acted upon rather than from a confusing or conflicting form. McFarlane and Pliner found ply people who consider nutrition to be important have healthy food preferences. Which implies that information on its own is not sufficient to promote healthy eating practices but that there are also individual differences based on attitudes towards healthy eating.
IDA
Research into this topic area can help to construct beneficial practical applications to create eating programmes that shape and maintain healthy dietary practices in a variety of different age groups. Weight Watchers is an example of this, its ultimate goal is to help individuals to lose weight so that they become healthy and that this weight is then maintained for the future by using the taught eating practices. This programme highlights the importance of psychological principles into successful dieting as not only is the information source trustworthy, but social environments are created including positive role models, member support and vicarious reinforcement that urge people to gain confidence and motivation to continue their journey to achieve long-term success.
Explanations for the success and failure of dieting
It is said that dieting is most successful when using calorie-controlled meals, a reduction in choice over what and when they eat and a process of reinvention creating a new identity and no longer seeing themselves as overweight. Weight Watchers is an example of this, its ultimate goal is to help individuals to lose weight so that they become healthy and that this weight is then maintained for the future by using the taught eating practices. This programme highlights the importance of psychological principles into successful dieting as not only is the information source trustworthy, but social environments are created including positive role models, member support and vicarious reinforcement that urge people to gain confidence and motivation to continue their journey to achieve long-term success.
Success
Other than Weight Watchers, a helpful way of maintaining dietary practices is through setting achievable small targets that are more likely to be obtained and keep motivation high, as well as using operant conditioning, to rewarding themselves with new clothes for example, once they've hit a target weight (also helps relapse prevention). Lowe et al found that an average of 71.6% of Weight Watchers members maintained a body weight loss of at least 5% indicating that social support is not only important for weight loss, but maintenance also.
Initially, genes make is harder for some people to go through the dieting process and then maintain it. One gene codes for the enzyme lipoprotein lipase (LPL) which helps to store calories as fat, after weight loss levels of LPL were found to increase and so making it difficult to keep the weight off.
This demonstrates that there is complexity in achieving a successful diet involving behavioural, cognitive and biological understandings. But that such success can be measured in terms of peoples psychological well-being and reduced costs to health services.
Refuting and supportive evidence
Restraint Theory (Herman and Mack) was developed as an attempt to explain both causes and consequences associated with the cognitive restriction of food intake. Suggesting that attempting not to eat increases the probability of overeating. Yet the treatment of obesity commonly recommends restraint as a solution to excessive weight gain, however, failed attempts at restraining often leaves people feeling depressed and unable to control their weight. Although obesity may not necessarily be caused by overeating, overeating may be a consequence of obesity if restraint is recommended as a treatment (Ogden).
Keys et al found individuals given half their daily food intake for 12 weeks lost 25% of body weight and became so obsessed with food that they hoarded or stole it without thinking. Suggesting that restrained eating leads to alterations in cognitive state. From research findings, most of which is supporting, the Restraint Theory appears to be an effective explanation of why some people are unsuccessful at dieting and what causes them to be so in the first place.
IDA
Research into dieting is gender biased to a great extent, with most focus on females thus research findings cannot be generalised to males as they differ both biologically and cognitively. Anorexia nervosa, for example, is primarily female complaint, around 15% of males also suffer and so it is important to understand male dieting behaviour too.
Biological/neural/evolutionary explanations of obesity

Bio
According to evolutionary psychology body size appears to run in families, as it was found that if both parents were obese there was an 80% chance that there children will also be obese. Stunkard et al looked at the BMI of two groups, of identical twins living in different environments, and non-identical twins living in the same environment. Finding that genetic factors accounted for 66-70% of the variance in their body weight thus it is a strong explanation for obesity.
A single gene, the 'ob gene' which produces leptin has been found to be associated with obesity in humans, and humans that don't produce leptin are the ones that are obese. After Farooqi injected leptin into two overweight children it resulted in a decrease in food intake and weightless of 1-2kg per month. Although this study does support the notion of genetic influence, because Farooqi only used two children, an extremely limited sample, we are unable to generalise that all overweight people do not produce leptin.
Neural
Catecholamines are chemicals that influence satiety and trigger hunger, such drugs include Amphetamines and Amitryptiline so that excess amount of these in turn leads to a greater risk of obesity. This can be used to enhance our biological understanding of obesity but some aspects still remain unclear due to the interaction of social drives such as the desire to be thin, availability of food; non-western rural areas only eat what they grow and other peoples' behaviour surrounding you, whether they encourage you to eat, or help you to stop.
Evolution
Our past has been characterised as having a lack of food and so storing excess body fat would have been an adaptive advantage. In the past, those that burned off more energy were unsuccessful and less likely to survive. This idea is called the 'thrifty gene' hypothesis and having this gene was extremely useful thousands of years ago but nowadays, as food production is at its highest we no longer require this gene. So instead of it being advantageous, it is now disadvantageous leading to obesity and putting greater pressure on our National Health Service.

Evolutionary explanations seem to challenge the concept of free will as people are viewed as a product of their inheritance, even though we now have more choice over what we eat unlike in the past where are diet was mainly herbivorous until meat was later introduced. To the extent that which we are able to overwrite our genes as such and prevent obesity.
Psychological explanations of obesity
Are mainly based around the behaviourist approach on operant and classical conditioning. Operant being learning through reinforcement and classical is learning through association, both of which lead to repetition of the learnt behaviour. In this case it is the inappropriate use of operant conditioning, whether that is the type of food or the amount of food, that eventually leads to obesity and comfort eating later on in life.
Devlin found that treatments based on operant conditioning resulted in weight loss not being maintained and suggesting that the use of rewards and punishments as a method of obesity treatment may not be effective in the long-term but classical conditioning offers a better explanation. As the Emotionality Theory (Schachter) states thin people eat in response to hunger whereas obese people eat in response to their emotions. Verplankton offered support for this idea as he found that low self-esteem was linked to the impulse buying of unhealthy products. This suggests that unhealthy eating habits and behaviour are used as a coping mechanism for people with body dissatisfaction. By helping patients to identify cues triggering inappropriate eating and then learn new responses to them levels of obesity can be reduced.
Biological
According to evolutionary psychology body size appears to run in families, as it was found that if both parents were obese there was an 80% chance that there children will also be obese. Stunkard et al looked at the BMI of two groups, of identical twins living in different environments, and non-identical twins living in the same environment. Finding that genetic factors accounted for 66-70% of the variance in their body weight thus it is a strong explanation for obesity.
A single gene, the 'ob gene' which produces leptin has been found to be associated with obesity in humans, and humans that don't produce leptin are the ones that are obese. After Farooqi injected leptin into two overweight children it resulted in a decrease in food intake and weightless of 1-2kg per month. Although this study does support the notion of genetic influence, because Farooqi only used two children, an extremely limited sample, we are unable to generalise that all overweight people do not produce leptin.
Biological explanations of obesity are good as they are based on sound empirical data from rigorous scientific investigation and make use of objective methods such as gene testing and genetic screening. This is advantageous as it may in the future allow for the development of sound biological therapies implicated during early childhood to prevent pre-disposed obesity.
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