- Created by: Catriona Stobie
- Created on: 20-05-14 12:51
Psychological Explanations for Food Preference
Learning theories help to explain how our food preferences develop. Firstly classical conditioning can be linked to our food preference. This involves associating foods with particular events or emotions which then leads to either a preference or disliking of particular foods. For example if you were to eat jelly and ice cream at a birthday party where you were having fun then you are likely to associate jelly and ice cream to positive feelings and therefore will develop preference for this food, however if you were to throw up after eating jelly and ice cream then it would be associated to negative feelings and so a disliking would develop instead. Secondly is operant conditioning in which the eating of certain foods is either positively reinforced or negatively reinforced, leading to the development of preference. For example if a child is eating their vegetables this is often supported by the parent with praise. This praise acts as positive reinforcement and so leads to the child being more likely to repeat the behaviour and develop a preference for vegetables. Thirdly is social learning theory which suggests that children develop their food preferences based on observing and imitating others, for example if they viewed somebody else enjoying a particular food they will then eat this food with the expectation that they too will enjoy it. This leads to the development of preference for certain foods. Health concerns are also viewed as an explanation for our food preferences and the way we view our health is mostly down to what we see on advertisements and health campaigns which encourage the eating of foods such as fruit and vegetables as well as foods with high sources of protein. It is suggested that health acts as a motivation for food preference and as a result we tend to prefer the foods that are advertised as being healthy.
Success & Failure of Dieting
The success and failure of dieting can be contributed to several various explanations. The first explanation for the success of dieting is restraint theory which suggests that conciously restraining our food intake can result in successful dieting but only if we have a high level of internal control, meaning that we are not influenced by external factors such as being surrounded by nice smelling foods or being pressured by friends to eat certain things. The second explanation for successful dieting is body dissatisfaction which suggests that if a person is highly motivated to lose weight in order to achieve a certain body size and shape then they will be more successful in their dieting attempts. The first explanation for the failure of dieting is the boundary model which looks at the disinhibition of restraint effect. This is also known as the what-the-hell effect and occurs when a dieter crosses their restraint boundary and then chooses to overeat to an extortionate level. Crossing this boundary can be a result of pre-loading as well as stress or anxiety and represents dieting failure.The second explanation for failure of dieting is theory of ironic mental processing which suggests that the more we try not to think about something the more we do. In terms of dieting we often try not to think about food in order to avoid eating it however this theory suggests that the more we try not to think about food the more we become preoccupied by it and the more we become likely to overeat. This would result in the failure of dieting.
Neural Mechanisms for Eating Behaviour
One neural mechanism involved in controlling our eating behaviour is the dual centre model of feeding which involves the lateral hypothalamus (LH) and the ventromedial hypothalamus (VMH). Glucoreceptors in the body detect when glucose levels fall past a specific level and send an impulse to the LH. The LH is said to be involved in turning on eating and in response to this impulse will produce feelings of hunger in the body. We are then stimulated to search for and consume food which then raises our blood glucose levels again. Glucoreceptors also then detect when glucose levels rise past a specific level and will send an impulse to the VMH when this happens. The VMH, which is said to turn off eating, responds by producing feelings of satiety. This causes us to stop eating so that our glucose levels do not continue to rise. This dual centre model is very important in maintaining homeostasis as it ensures our glucose levels are always at a particular set level and therefore is a huge influence on our eating behaviour. Another neural mechanism involved in controlling our eating behaviour is neuropeptide Y which is a neurotransmitter secreted in the hypothalamus that is believed to turn on eating by producing feelings of hunger. Leptin, a hormone, inhibits neuropeptide Y and this turns eating off by preventing feelings of hunger. Both the neuropeptide Y neurotransmitter and the leptin hormone combine to maintain homeostasis in order to prevent undereating and overeating.
Evolutionary Explanations for Food Preference
The evolutionary explanation for food preference suggests that our food preferences are an innate behaviour as a result of such preferences being adaptive in the EEA. This would have meant that those with these preferences would have been better able to survive and reproduce to pass on their genes and therefore would have fixed these food preferences into our gene pool. Preference for meat is one preference that is viewed as being a result of evolution. Meat is high in protein and offers high energy content. Protein aids healthy growth and high energy content allows for high activity levels. These features would have been adaptive in the EEA as healthy growth would increases survival chances and high activity levels would have allowed for successful hunting and gathering as well as successful reproductive efforts. Preference for sweet foods is also viewed as an evolutionary development. Sweet foods are often have high calorific content and signal when food is ripe or non-poisonous. These features would have been adaptive in the EEA as high intake of calories would have provided energy for high activity levels and being able to recognise when foods were poisonous would prevent death by poison and so would increase survival chances in order to reach reproductive age. Preference for salt is also a preference that is viewed as being a result of evolution. Salt is key for healthy bodily functioning for example it helps to maintain correct blood pressure and the correct concentrations of substances in cells such as water. Salt in the EEA would have been a scarce resource and so preference for it would be advantageous as our ancestors would have sought after foods with high salt content and this would have been adaptive as it would led to consumption of salt which was key to remaining healthy and surviving to reproductive age.
Psychological Explanations for Anorexia Nervosa
One psychological explanation for anorexia nervosa is the psychodynamic approach. Bruch suggests that anorexia nervosa is a result of ineffective parenting. By this he describes ineffective parents as incorrectly identifying their child's needs, for example feeding them when they actually desire affection. This leads to the child growing up and being overly reliant on their parents for defining their needs. As these children reach adolescence they begin to seek independence however due to being over-reliant on their parents they find it hard to be autonomous. In order to feel they are autonomous they will take extreme control over the body shape and size through controlling and fiercely restraining their eating. This results in the development of anorexia nervosa. The family systems theory on the other hand, which is also part of the psychodynamic approach, suggests that anorexia is a result of being part of an enmeshed family. An enmeshed family is a family described as having members that have no real identifiable role and they do everything together as a unit. As children in enmeshed families get older they look to develop an identifiable role as they try to become independent and because of this they may take excessive control over their eating habits and look to alter their body shape and size. Often parents in an enmeshed family will avoid conflict and look to focus on their ill child.
Biological Explanations for Anorexia Nervosa
One biological explanation for anorexia nervosa is a chemical imbalance in the brain. These chemicals are known as neurotransmitters and are involved in creating nerve impulses. One neurotransmitter involved in anorexia is serotonin. It is suggested that people with anorexia have abnormally high levels of serotonin in comparison to what their body feels is correct. Food contains an amino acid known as tryptophan. Tryptophan is involved in the production of serotonin and so reducing food intake leads to reduction in tryptophan and therefore serotonin levels. This leads to the person's serotonin levels returning to natural levels. This may also explain why anorexia sufferers say that not eating eases their anxiety as high levels of serotonin are linked to high levels of anxiety. High dopamine has also been associated with anorexia nervosa. It has been found that anorexics often have high levels of dopamine in their basal ganglia. Dopamine is related to interpreting harm and pleasure and abnormal levels of dopamine lead to this interpretation becoming flawed. This results in anorexics viewing activities that are seen as pleasurable by others as not at all pleasurable. This includes eating and therefore explains why anorexics will eat very little as they do not find pleasure in eating.
Evolutionary Explanations for Anorexia Nervosa
There are two evolutionary explanations for anorexia nervosa, both of which suggest that the development of anorexia nervosa in the EEA was an adaptive behaviour as it boosted survival and reproductive chances. The first explanation is the adapted to flee hypothesis. This hypothesis suggests that because our ancestors were hunter-gatherers they were nomadic and often had to move whenever resources were depleted. If resources were depleted then our ancestors would have been lacking food and in usual circumstances the response to extreme hunger is often fatigue and depression. In anorexia nervosa sufferers though they tend to be very energetic and restless. Developing such a disorder would allow our ancestors to successfully move to another more habitable place where more resources were available. This would have increased survival chances and therefore would have helped our ancestors to reach reproductive age and pass on their genes to offspring, including the anorexia nervosa characteristic. The second explanation is the reproductive suppression hypothesis. Many anorexia sufferers are known to be infertile as they do not eat enough food to gain enough energy for the oestrus cycle to take place each month. In the EEA this may have been an adaptive behaviour as it would have prevented reproduction in temporarily unfavourable conditions. Such conditions could have included high female competition or lack of favourable mates. Stimulating infertility would lead to the women being unable to reproduce whilst these temporarily unfavourable conditions existed. When conditions improved the women would then be able to become fertile again. This allows for the females to be able to pass on the best genes available on to their offspring and is therefore adaptive.