Eating Behaviour

Social Learning Theory-
-Parental modelling  may account for food preferences in children, as parents are in control of the food brought and served in the house. Brown and Ogden also found correlations between parents and children in terms of their snack-food intake, eating motivations and body dissatisfaction, showing that children develop similar attitudes to food as their parents.

-Media effects are also included within social learning theory, as the media can influence both what people eat and their attitudes to food. However, factors such as a person's age, income and family circumstances may limit their behaviour in response to the media. For example, children may not have the ability or money to buy a food they have seen in a magazine

Cultural influences can affect levels of body dissatisfaction, such as negative feelings and thoughts about the body which can influence people's eating behaviour. Two factors are ethnicity and social class. 
-Ethnicity Powell and Khan suggest that body dissatisfaction and related eating disorders may be more characteristic of white women than black or Asian women. Ball and Kenardy studied over 1400 women between the ages of 18 and 23 in Australia, For all ethnic groups, the longer time spent in Australia, the more women reported attitudes and eating behaviours similar to women born in Australia. This is called the 'acculturation effect'. 

Mood and eating behaviour- some explanations of eating behaviour see the behaviour as a temporary escape from negative moods such as sadness and anxiety. 
Binge-eating- Individuals with bulimia complain of anxiety prior to binge. Davis showed that one hour before a binge, bulimic individuals had more negative mood states than one hour before a normal snack or meal. This finding is also true of non-bulimic populations. Wegner had students record their eating patterns and mood states for two weeks. Binge days were characterised by low mood compared to non-binge days. 
Comfort eating- Garg observed the food choices of 38 participants as they watched either an upbeat, funnt movie or a sad depressing one. popcorn vs grapes.

Social learning theory
:) Research support- Meyer and Gast- who surveyed 10-12 y/o girls and boys and found a positive correlation between peer influence and disordered eating. The 'likeability' of peers was considered the most important factor in this relationship. Birch and Fisher also found that te best predictors of a daughter's eating behaviours were the mothers' dietary restraint.
:( IDA social learning theory is reductionist- eating behaviour cannot be explained solely by imitating fashion role models in the media. Evolutionary explanations of food preferences suggest that our preferences for sweet and fatty foods are the result of an evolved adaptation among our distant ancestors.
Cultural influences
:( contradictory research findings for ethnicity- Mumford found that the influence of bulimia was greater among Asian schoolgurks than among their white counterparts.
Mood and eating behaviour
:( Contradictory research findings for comfort eating- Parker challenges the view that chocolate is the ultimate comfort food, as it has been found that chocolate has a slight antidepressant effect for some people, and therefore can prolong a negative mood.
:( IDA Gender Bias Siever found that homosexuality is a risk factor for the development of eating disorders males.
:( AO3 pronlems generalising from studies
:( Cultural differences Rozin argues food functions differently for different cultures.

Three types of diet strategy have been identified: 1) restricting the total amount of food eaten, 2) restricting the types of food eaten, 3) avoiding eating for certain periods of time.

Restraint theory- Herman and Mack restraint theory explains the causes and consquences of restricting food intake. They suggest that trying not to eat actually increases the probability of overeating. 
Linked to this is the 'boundary model' (Herman and Polivy) which explains why dieting can lead to overeating. According to the boundary model, hunger keeps our intake of food above a certain minimal level and satiety keeps our intake below the maximum level. Dieters tend to have a larger range between hunger and satiety levels as it takes them longer to feel hungry and more food to satisfy them. Restrained eaters also have a self-imposed desired intake. Once they have gone over this boundary they continue to eat until they reach satiety.

The role of denial- Cognitive psychology has shown that trying to suppress or deny a thought often makes it more prominent. Wegner - white bear- 'theory of ironic processes of mental control'

Key is in the detail- Redden suggests that in order to be successful at dieting people need to pay attention to the details of what they are eating. Jelly bean experiment- gave 135 people 22 jellybeans each, those given details found the task more enjoyable. 

Restraint theory- 
:) Implications for obesity treatment Ogden suggests that overeating may be a consquence of obesity if restraint is recommended.
:( Limited relevance- restraint theory proposes an association between food restriction and overeating. However, Ogden points out that this is not the case with anorexics, who severly restrain their eating. 

Ironic processes of mental control- 
:) research support- Soetens participants were divided into restrained and unrestrained eaters. The groups were further subdivided into those who were either high or low on disinhibition. The disinhibited restrained group used moe thought suppression than the other groups and also showed a rebound effect after. This shows that trying to suppress thoughts of food can lead to thinking about it more and therefore overeating.
:( limited experimental effects- Wegner admits that the 'ironic effects' observed in research are not particularly significant. However, these effects may underlie more serious pathological forms of eating behaviour, so their influence could be considered important in terms of human costs if they can detect a chance of disordered eating developing. 

:) IDA real world application- anti-dieting programmes- Higgins and Gray found that participation in these programmes was associated with improvements in both eating behaviour and psychological wellbeing, and with weight stability rather than change.
:( IDA cultural bias in obesity research Misra asian adults are more prone to obesity than europeans, and asian children and adolescents have a greater central fat mass when compared with other ethnic groups.
IDA free will or determinism? Genes? lipoprotein lipase? 
:( AO3 limitations of anecdotal evidence- many studies rely on the personal accounts of individuals. 

Homeostasis- restores the body back to optimum state. but there is a significant time lag between mechanisms operating to restore equilibrium and the body registering their effect.

There are 2 separate systems in the body for turning eating on and off. Hunger increases and glucose levels decrease. A decline in glucose activates the Lateral Hypothalamus, resulting in feelings of hunger. The person then eats food, causing the glucose levels to rise again, and this activates the ventromedial hypothalamus leads to feelings of satiety.

Increase in glucose= Leptin
Decrease in glucose= Ghrelin

Damage to the Lateral hypothalamus can cause aphagia, which is where you don't feel hungry so you don't eat. (Wickens study of rats)

Damage to the ventromedial hypothalamus can cause hyperphagia which leads to over eating.

:( Limitations of a homeostatic explanation- It would be more adaptive if the system maintained bodily resources above optimal level, as this would act as a buffer against future lack of food availability. 

:( The role of the lateral hypothalamus- damage to the LH also causs deficits in other aspects of behaviour such as thirst and sex. It is not the brain's eating centre. 

:( Neuropeptide Y- recent research on NPY Marie genetically manipulated mice so that they didn't produce NPY. These mice did not show any subsequent decrease in their feeding behaviour. The researchers suggest that the hunger stimulared by NPY injections was caused by the experiment itself, as the NPY injections flood the body with greater amounts of NPY than would be produced normally. 

:( the role of VMH- Gold found that damge restricted to the VMH alone did not result in hyperphagia and only produced over eating when other areas were also damaged such as the PVN. However, subsequent research has not been able to replicate Golds findings. 

:( there nay be factors other than neural mechanisms that influence hunger- Lutter found that the body produces extra quantities of the hormone ghrelin in response to stress. (why people eat when stressed) 

:( IDA evolutionary approach- food has a positive incentive value, people eat because they develop a liking for particular tastes that are associated with foods which promote our survival. 

:) IDA real world application of research into NPY Yang has shown that NPY is also produced by abdominal fat, suggesting a vicious cycle where NPY is produced in the brain, leading to more eating, and the production of more fat cells, which produce more NPY. 

The environment of evolutionary adaptation (EEA)- means the environment in which a species first evolved. Humans first emerged as a separate species around two million years ago on the African savannah, and were a hunter-gatherer society. Early diets included plants and animals that were part of the natural environment. Fatty foods were desireable as well as foods rich in calories to enable survival, which reflects the tastes of humans today. 

Preference for meat-  Milton argues rhat without animals in their diet, it is unlikely that humans could have gained enough nutrition from vegetable sources to evolve into the active and intelligent creatures they became. Meat supplied early humans with all the essential amino acids, minerals and nutrients they required allowing them to supplement their diet with plant-based foods. 

Taste aversion- Garcia- rats

The medicine effects Garcia rats

:) the importance of calories in early diets Gibson and Wardle probide evidence to support the importance of calories in an ancestral diet- which fruit is preferred by children?

:) Early humans could not have been vegetarians Cordain argued that early humans consumed most of their calories from sources other than saturated animal fats.

:( Not all food preferences can be explained by evolution- Many things that were essential to our ancestors are now harmful to us so we avoid them to lead a healthy lifestyle (saturated animal fats)

:) Taste aversion can be explained in humans- Seligman claimed that different species have a biological preparedness to learn different aversions more easily than others. 

:) the ability to detect toxins is adaptive-Sandel and Breslin screened 35 adults for the bitter taste receptor gene. Pps rated the bitterness of various vegetables, some with toxin in and some with not. Those with a sensitive form of the gene rated the toxin veg as 60% more bitter than rhose with the insensitive form of the gene. The ability to detect these natural toxins would confer a selective advantage on our ancestors, which explains why the genes are so widespread today.

:) IDA cultural differences in food preferences

:)/:( testing evolutionary hypothesis- compared to animals, are we less worried about survival now and more worried about advertising and fast food?

1. Binge- secret binge-eating
2. Purge- compensation
3. Frequency- at least twice a week for 3 months
4. Body image- inappropriate perception of own body
5. Different from anorexia- usually normal weight range for their height, do not change weight.

Coopers cognitive model- Developmental factors, maintaining factors

The functional model (Polivy)- individuals enage in binge eating behaviours as a way of coping with identity problems. Wheeler proposed that negative self-image abd a desire to escape from difficult life issues could therefore predict the onset of bulimic behaviour, the consquence of which is a 'diffuse-avoidant identity style'. Individuals in this state feel externally controlled, and use emotion-focused coping strategies. 

Relationship processes
Anxious attachment in intimate relationships- Women attempt to change themselves in order to meet some perceived ideal held by men about what is considered attractive. Anxious attachment in adult relationships is characterised by a strong desire for closeness and a fear of abandonment (Hazan and Shaver) and people with this attachment style blame themselves for rejection. Evans and Wertheim found a relationship between anxious attachment style and BN. 

Coopers cognitive model
:) Supporting evidence - Leung found that a lack of parental bonding was linked to the development of dysfunctional core beliefs among bulimics, which have been linked to bingeing and vomiting symptoms. 
:) Implications for treatment- based on cognitive psychology, should be able to use CBT. Fairburn carried out a follow-up study of bulimic patients who had CBT and found that only 50% were symptom free and 37% still met the criteria.

The functional model
:) Supporting evidence Polivy found thatm compared to ordinary dieters, stress-induced dieters consumed larger quantities of food regardless of its taste.
:) Implications for treatment- a diffuse avoidant identity style has been shown to make individuals susceptible to a variety of health and social problems, including self-harm. Treting early symptoms can prevent BN and the development of an diffuse avoidant personality identity style. 

Relationship processes
:( Bulimia or depression?
:( IDA cultural bias in bulimia research- mainly in Western societies, Keel and Klump found that bulimia is a culture bound syndrome whereas anorexia is not. 
:( IDA a heterosexual bias in bulimia research

Neural explanations

Serotonin- The fact that depression and BN occur together suggests that they have a common cause and both have been linked to imbalances in serotonin. Controls anxiety levels as well as perceptions fo hunger and appetite. Kaye compared levels of neurotransmitters in recovered BNs and a control group of non BNs. The levels of serotonin were abnormal in recovered BNs but dopamine and adrenaline were the same in both groups. Low levels of serotonin result in depression and high levels lead to anxiety. Purging lowers serotonin levels, leading to bingeing, which increases serotonin levels, which causes purging etc.. 

Nitric oxide- is a neurotransmitter involved in regulating food intaje. NO is delivered by plasma nitrite where is causes the production of cGMP. Vannacci  compared plasma nitrite and cGMP levels of 31 female BN patients with a control group and found that both substances were higher in the BN group. 

Evolutionary explanations

The sexual competition hypothesis- Abed suggests BN is a direct consequence of the evolved need to compete with other females to attract a mate. There are two aspects-

The evolution of nubility, Sexual competition.

Neural explanations- 

:) Serotonin and SRRIs- must be possible to treat 
:) Tryptophan (used to make serotonin in the body)Smith recovered BNs some food had tryptophan in, those who ate those had symptoms showing serotonin has an affect. 

Evolutionary explanations-

:) The theory fits the statistics- older people want to stay attractive too, used to not be recognised, gynocentric. the incidence of BN in females is 33 times greater than in males. 

:) Bulimia and gay men

:) is BN universal?? different cultures have different ideas of attractiveness. 

:( Ageism in research- Mangweth-Matzek- analysed survery responses from 475 women aged 60-70 18 of those women met the criteria to be diagnosed for eating disorders.