- Created by: George Mangham
- Created on: 08-06-13 15:57
Attitudes to Food
Attitudes are judgements and develop on the ABC model.
A-The affective response is an emotional response that expresses an individuals degree of preference for an entity.
B-The behavioural intention is a verbal indication or typical behavioural tendency of an individual.
C-The cognitive response is a cognitive evaluation of the entity (beliefs about the object).
How do attitudes develop?
Direct Experience- Related to taste and the physical and psychological consequences of eating certain foods.
Observational Learning- Depends on familiarity, parental example and cultural factors.
Theory of Reasoned Action
Ajzen & Fishbein (1980)- Theory of Reasoned Action
Social Cognition Model- Two factors influence intention; Attitude towards behaviour and Perceived social pressure. Place emphasis on attitude of individual.
A persons behaviour is determined by their intention to perform the behaviour. This intention is, in turn, a function of their attitude toward the behaviour and his/her subjective norm.
Evaluations of Theory of Reasoned Action:
Doesnt take into account perceived control over actions
Intentions dont always predict actions
Previous experience might influence attitude
Doesnt consider irrational decisions
Theory of Planned Behaviour
Ajzen (1985)- Percieved behavioural control influences intentions. General rule, the more favourable the attitude and the subjective norm, and the greater the percieved control then the stronger should the persons intention to perform the behaviour in question.
Povey et al (2000)- Found that the TPB explained 57% of the varience in intentions to eat 5 portions of fruit and veg. Participants were then assesed one month later on their actual behaviour and found that TPB accounted for 32% of the variance in fruit and veg consumption.
Health Belief Model
Aims to predict the liklihood that a person will carry out a health behaviour. The HBM is based on the understanding that a person will take a health related action eg a negative health condition can be avoided.
Depends on two assessments made:
Evaluating the threat; Percieved seriousness, percieved susceptability, cues to action and other variables.
Cost-benefit analysis; Do the percieved benefits of changing behaviour exceed barriers, Benefits include improved health, relief from anxiety etc, Barriers include cost, situational factors etc.
Socio-economic Factor Affecting Food Choice
It has been found that lower socio-economic groups consume less fruit and veg (Ministry of Agriculture 1999).
Cade et al (1999)- Found that in the UK the cost of a healthy diet was more expensive than a non-healthy one.
Mooney (1990)- Found that recomended foods following UK dietary guidlines were more expensive than alternative foods, particularly in deprived areas.
Leather (1995)- Low income families suffer more from dominant supermarkets (83% market share) because the ones without transport have to pay extra to travel to the supermarket therefore making it dearer to obtain food.
Anderson & Cox (2000)- The bulk of food purchased and experiences relating to transport were frequently mentioned factors in the UK.
Mood Affecting Food Choice
Comfort Foods are those that when consumed induce a psychologically comfortable and pleasurable state for the consumer.
Bellisle et al (1940)- Compared the amount and types of food eaten by a group of men on the morning before they were to undergo surgery, with a morning at a later date where they were not due to undergo surgery. They found that there was no link between stress and changed eating behaviours.
Tice et al (2001)- Found that people responded to distress by eating more fattening and unhealthy foods, however this tendency was reversed if the participants believed that eating unhealthy, fattening food would not change their mood.
Antelman et al (1975)- Found that by inducing stress in rats leads to an increase in gnawing, eating and licking food.
Culture Affecting Food Choice
Vegetarians, Religion etc
Eating at home- Most people eat at home and this has been suggested to be the healthier option of consumption. But in 1990 the percentage of people eating out ros from 34% to 47% and these increases have been linked to the increase in obesity within the population.
School- 78% of schools have easily accessable vending machiences therefore encouraging the children to eat unhealthy food at school.
Portion Size- The amount of food that an individual eats can influence their attitudes to food. In some cultures, large portions imply a greater biological build. Rolls et al (2000) found a positive linear relationship between larger portion size and intake in children between 4 and 5.
Parental Influence Affecting Food Choice
Children link eating food with the reward from parents. Birch et al showed that there was an increased preference towards foods which were associated with positive adult attention.
Anderson et al (1994)- Found Scottish participants had a strong preference for familiar veg and were wary of new varieties.
Brug et al (1995)- Found that habit was a strong determinant for consumption of boiled veg, salad and fruit.
Body disatisfaction leads to dieting. According to Ogden (2007) the reasons for people going on a diet are; Media Influence, Family, Ethnicity, Social Class and Peer groups and Social Learning.
Reasons as to why diets fail:
Restraint Theory (Ogden 2003)
Cognitive Shifts (Herman & Polivy 1984)
Mood (Ogden 2003)
Denial (Wegner 1994)
Biological-Role of Leptin
Restraint and Overeating
Herman & Mack 1975- Pre-load/Taste test- Compare restraint of dieters and non-dieters.
Participants were give either a high calorie or low calorie pre-load. Participants told it was a taste test and that they could eat as much as they like.
The results suggested that restrained eating is associated with eating more at certain times. They found that dieters who had the high calorie pre-load ate more.
Concluding that periods of restraint actually lead to binging on food.
Wardle & Beales (1988)
They did a lab test assesing food intake at 4 and 6 weeks. The participants were randomly assigned to a diet, exercise or control group.
Found that the participants in the diet group ate more than those in the exercise and control group.
Supporting the idea of restraint theory.
Why Do Dieters Overeat?
Counter-regulation- People eat more after a high calorie intake.
Disinhibition- People eat more because the restraints have been loosened.
"What the hell" effect- A small lapse is percieved as a diet failure-> binge with the intention to start again.
Boundary Model (1984) Herman & Polivy
Hunger keeps food intake above minimum level. Satiation works to keep food intake below max. Betwen the two is the 'diet boundary'.
Dieters set a boundary and try to stay within it. But on occastions they cross this boundary and this leads to a food binge.
Dieters have a large boundary between hunger and satiation, therefore the impact on food intake is larger especially if the boundary is breached.
Evaluations of Restraint Theory
If restraint leads to overeating and obesity is treated with restrain diets then obese people will be left depressed at failure, therefore overeating may be a consequence of obesity. (+)
Cannot explain the prolonged restricting behaviours of anorexics. (-)
Studys done with small samples (-)
Mood on Dieting
Dieters may overeat due to lowered mood.
"Masking Hypothesis" Ogden 2003
Polivy & Herman
Told participants they had passed or failed a cognitive task. They then presented them with unlimited amounts of food or food in controlled amounts. The dieters who were given unlimited amounts of food attributed their distress to eating rather than the task failure. Concluding that dieters may overeat in order to shift responsibility away from other areas and onto their eating.
Wansink et al
Recorded the food choices of 38 participants who were offered popcorn or grapes as they watched a comedy or a sad film. They found that those who watched the sad film ate 36% more popcorn while the comedy group consumed more grapes. Concluded people in sad moods try to jolt themselves out of gloom by eating unhealthy comfort foods. While those in a good mood wanted to maintain their good mood by eating nutritional comfort food.
Cognitive Shifts and Denial
Overeating often involves a breakdown of self control or 'motivational collapse'.
Wegner et al (1987)- White Bear Study
Asked participants to not think about a white bear and ring a bell when they do. They also asked other participants to think about the bear. Found that those who were told not to think about the bear rang their bells more often.
Denial- The theory of ironic process of mental control.
Denial backfires as soon as food is denied becasue it becomes attractive.
Biological Reasons Diets Fail
Mark (2006)- Suggests that diets are always likely to fail as they do not address the undelying biological problems such as those to do with the leptin hormone.
Harvel (2000)- Higher leptin levels decrease hunger and eating.
Humans who are eating low-calorie diets have low levels of leptin meaning they feel increased levels of hunger, perhaps explaining why it is difficult to maintain weight loss.
Laposky et al (2007)- Suggests that obesity is linked genetically to leptin resistance.
When Do Diets Succeed?
Kirkley et al (1988)- Found restrained eaters consumed less.
Diets that involve strategies are effective in changing eating behaviour.
Rodin et al (1977)- Role of individuals beliefs and motivation.
Healthy Eating Programmes.
Kiernan et al (1998)- People who are more dissatisfied with their body shape at baseline are more likely to succeed in dieting.
Media Affects on Attitudes to Eating
MacIntyre et al (1998)- Media had a big impact for people on what they eat and their attitudes to certain foods. However, personal circumstances play a role in what they eat. But the media can play a significant role.
Jamie Oliver Ministry of Food use of shock tactics.
Jamie Oliver School Dinners- Educating parents and the government about poor diets.
Dixon (2007)- Found that heavier Tv use with more Tv commercial viewing were associated with more positive attitudes towards junk food and heavier Tv use was also associated with higher junk food consumption. Also found that ads for nutritional foods promoted positive attitudes and beliefs in children.
Neural Mechanisms in Eating
Hypothalamus- Controls homeostatis in the body. The hypothalamus is the the hunger centre (the area of the brain that controls hunger). The dual-centre theory of feeding behaviour- The body has two seperate areas of the hypothalamus that are involved in eating.
1) Turns eating 'on'- Low glucose levels=activates the lateral hypothalamus=hunger feelings.
2) Turns eating 'off'- Increased glucose levels=activates the ventromedial hypothalamus=satiation.
Lateral Hypothalamus (LH)- Initiates eating and responds to decreased blood glucose, Increase in ghrelin.
Brobeck & Anand found that leisions in the LH in rats caused decreased eating and subsequent weight loss.
Ventromedial Hypothalamus (VMH)- Inhibits eating when we are full and responds to an increase in blood glucose, decrease in ghrelin and increase in leptin.
Lashley- Leisions in rats brain if cut in VMH causes them to continue to eat and consequently overeat.
Role of Ghrelin
Ghrelin is a hormone produced in the stomach and tells the body to start eating.
Cummings et al (2004)
Monitored 6 participants ghrelin levels every 5 minutes and asked participants to assess their levels of hunger every 30mins.
Found that in 5 of the 6 participants there was a significant correlation between ghrelin levels, emptiness of the stomach and hunger. Therefore supporting the role of ghrelin in eating behaviour.
Ghrelin injections result in increased food intake in animals.
Gastric bands used in treating obesity reduce ghrelin.
Role of Leptin
Leptin is a fat hormone that signals that caloric storage is high. The more fat a person has the more leptin they have.
Zhang et al (1994)- Gave some mice two copies of the obesity gene (ob). ob/ob mice had a tendency to overeat foods high in fat and sugar. Have defective genes for the protein leptin so leptin is not produced. Injecting the ob/ob mice with leptin caused them to dramatically loose weight, showing leptin is associated with over eating.
London and Baicy (2007)- Gave a leptin replacement to 3 adults with the 'ob' gene mutation and found that it normalised body weight and eating behaviour.
Evaluations of Neural Mechanisms
Could lead to medical treatments (+)
Very scientific and objective (+)
Use of animals (unethical) (-)
Lack of ecological validity (-)
Physiological drives can be overridden (-)
Role of Neurotransmitters
Three types that influence appetitie; Catecholamines (dopamine)- fight or flight hormones, Serotonin- activates muscles used for feeding and Peptides- short polymers formed from the linking of amino acids.
Neurotransmitters that increase food intake:
Neuropeptide Y- Rats injected with this neurotransmitter continue eating large amounts of food even when full. It also seems to cause a preference for carbohydrates.
Galanin- Injections of this neurotransmitter cause an increase in food intake and preference for fats rather than carbohydrates in rats.
Neurotransmitters that decrease food intake:
Serotonin- Decreases food intake.
CCK- Causes reduction in appetite and satiation. And supresses weight gain.
There are Five tastes:
Sweet- Identify food rich in carbs to provide energy and ripe, edible food.
Sour- Associated with food that has gone off and therefore should be avoided.
Bitter- Associated with poisonous plants, should be avoided.
Salty- Critical for functioning of the cells.
And Umami (meaty taste) discovered in the 90's- Highly savoury, lots of energy from fat in the meat.
Evolutionary Theory of Food Preference
Humans behave to maximise survival of their genes. Survival depends on things such as maintaining health by obtaining sufficient nutrients to meet the bodys demands.
In todays world people find it hard to escape evolutionary pressures on them for particular food preferences (Stevens and Price, 2000)
Hence, nowadays people have a problem with overeating and gaining weight.
The evolutionary hangover is to conserve energy.
Preference For High Fat Foods
It is adaptive for animals to learn whih foods have high nutritional value. And fats contain twice as many calories as protein or carbs.
Humans needed the high fat foods in order to have more energy for hunting but also for heat during the cold winter months.
However humans do not now need to worry about staying warm during cold months so we do not burn of the excess calories.
This is an evolutionary hangover because we have not adapted to the current environment and we still are adapted to the environments in which we evolved.
Preference For High Calorie Foods
Gibson & Wardle- Found that when given children the choice to pick and fruit and veg, the children chose potatoes and bananaswhich are very high in calories. The reason why they chose these fruits and veg wasnt becasue they were sweet it was because they had the most calories.
Shows evolutionary preference.
Evolutionary Preference For Sweet Foods
Preference for sweet things would have been advantageous for our ancestort (Rozin 1982). The reason for this is because sweet foods are generally not poisonous and are usually edible.
De Araujo (2007) Tested the motion that a preference for sugary foods is based on the ability to taste sweetness.
Genetically Modified (GM) mice that lacked sweetness taste were given a sygar solutionand an sucralose solution (non-calorific). 'Sweet blind' mice had a preference for the sugar solution rather than sucralose solution, showing it is based on calorie content.
Suggests that a preference for calorie rich food is adaptive.
Preference For Bitter and Sour Foods
Evolutionary theory suggests bitter and sour foods are indicative of poison so should be avoided.
Mennella (2008)- Children reject medicine due to basic biology. Found that children are more sensitive to bitter tastes than adults.
There are 27 taste receptors for bitter and only 2 for sweet, showing that our body is designed to avoid bitter foods.
Simmen & Hladik (1998) Suggests that this shows the evolutionary importance of identifying harmful foodstuffs in our diet.
Preference For Salty Foods
Salt is essential for our body to function properly-concentration of salt must be kept at a specific level.
It has become adaptive for humans and other species to develop an innate preference for salt (Denton 1982)
Preference for salt seems to be universal.
At two years old children reject food that food that does not contain the expected amount of saltiness (Beauchamp 1987)
Fessler (2003)- High salt intake prevents against sudden dehydration. An adaptive mechanism calculates salt preferences as a function of the risk of dehydration as indicated by past experience of dehydration and maternal salt intake.
Preference For Umami Foods
Smil (2003) argues that it is the presence of animal fat that makes meat palatable and provides satiation, rather than the protein content.
Goudsblom (1992) Suggests the use of controlled fires increased meat consumption due to the benefits of roasting and smoking.
Standford (1992) Origins of human intelligence are due to meat eating. The development of intellect required for the social sharing of meat lead to the expansion of the human brain.
Umami taste allows humans to grow in social and language skills, therefore meat consumption has drove human evolution to where it is now.
Why We Cook and Use Spice
Introduced half a million years ago
An evolutionary advantage over other animals
Makes meat tender
Our molars have decreased in size during evolution
Kills bacteria in meat.
Kills bacteria in food
Spices are used more in hot countries-to preserve the food.
Food Neophobia and Taste Aversion
Food neophobia is an avoidance of unfamiliar foods.
Knaapila et al (2007)- Conducted a twin study and found there is a genetic basis to food neophobia.
Adaptive for us to learn which foods will lead to ill health.
Garcia and Koelling (1966) studied taste aversion in the lab using rats.
Rats more easily learned to avoid drinking flavoured when was followed by illness than when the drink was followed with electric shocks.
Morning Sickness often results in the avoidance of certain foods.
Morning Sickness is an adaption that could protect a vulnerable foetus from natural toxins.
By avoiding certain foods during the pregnancy women might improve their chances of having healthy children.
Taxman and Sherman (2000) looked at the results of 56 morning sickness studies covering 79,000 pregnancies in 16 countries. Found that the most likely foods to lead to morning sickness were meat, fish, poultry and eggs.
When food storage was not available, meat was most likely to carry parasites and pathogens that could harm a foetus, as well as putting the mother at risk.
Clinical Characteristics of Anorexia
Weight loss that is conseidered abnormal and drops below 85% of what was previouslly considered normal control of weight through unusual eating habits.
Anxiety about being overweight-this is an excessive fear. Not only obsessed with weight but fearful of weight gain.
Body image distortion-They do not see their own thinness and deny the seriousness of their low body weight. Continue to see themselves as fat despite the fact that bones can bee seen. Thinness is vital to their self esteem.
Cessation of menstrual periods (Amenorrhea)- Absence of periods for more than 3 months. Lack of menstrual cycle caused by inadequate nutrition.
Anorexic people have very child like features.
Biological Expalnations of Anorexia
States there is a physical cause for the disease.
Increase in seretonin levels linked to anorexia. Bailer et al (2007) found high levels of serotonin in anorexic people with binge/purge patients compared to healthy people.
Also highest levels in those with anxiety. Suggests persistant disruption of serotonin may lead to increased anxiety that may trigger AN. Kaye et al (2001) found drugs were effective in preventing relapse in recovering patients.
Increased dopamine levels is linked to AN. Kaye et al (2001) found there was an overactivity of dopamine in the basal ganglia of AN sample. Concluding that those with AN find it difficult to associate good feelings with things usually pleasurable.
Castro-Forniels (2006)- Adolescences with AN had higher levels of H acid (waste product of dopamine).
Lower dopamine levels in obese people (Wang, 2001)
During Pregnancy and Birth
Significant association between premature birth and development of anorexia (Lindberg & Hjem, 2003)
Birth complications lead to brain damage caused by hypoxia.
If the mother is AN during pregnancy they expose their offspring to a 'double-disadvantage' (genetic vulnerability and inadequate nutrition)
Season of Birth
Eagles et al (2005)- AN individuals are later in birth order compared to healthy controls. The more ellder siblings a child has whilst in the womb the more likely the mother will be exposed to common infections. The critical period for brain development is the 2nd trimester.
Willoughby et al (2005) found no seasonality effect in the development of AN where it is hot all year.
Neurodevelopmental Explanations Continued...
Holland et al (1984)- Found concordance rates for anorexia; 55% MZ twins, 7% DZ twins. Suggests genetic contribution but not cause. Other factors are needed as 45% of MZ twins do not develop AN.
Kortegoard et al (2001)- Found that identicle twins were more likely to share disorders than non identicle twins. Showing there is a genetic link.
Evaluations of Neurodevelopmental:
Cant pinpoint causality (-)
Two evolutionary theories: Reproductive Suppression Hypothesis (Surbuy, 1987) and 'Adapted to Flee' Hypothesis (Guisinger, 2003)
Reproductive Suppression Hypothesis
Low weight delays the onset of sexual maturation in response to cues in the environment about the probability of poor reproductive success.
It enables the female to avoid giving birth at times when conditions are not conductive to the survival of her offspring.
Anorexia is a 'disordered variant' of the adaptive ability-when we feel unable to cope with biological, emotional and social responsibility of womanhood.
Doesnt explain anorexia in men (-) Doesnt explain anorexia in the modern world (-) Doesnt explain why AN occurs in teenage years (-) How are AN symptoms passed on because this behaviour will decrease fertility and can kill (-) Face validity (Periods are delayed) (+)
Evolutionary Explanation Continued...
Adapted to Flee Hypothesis
Symptoms reflect adaptive mechanisms that caused migration when local famines occured.
Food restriction is a common feature when competition for food and migration behaviour.
Therefore for moder-day individuals, those with a genetic pre-disposition to Anorexia, loosing too much weight may trigger ancestral mechanisms.
'Holy Anorexia' in Middle Ages were saints that were recognised for miraculous ability to live without food.
Treatment implication-Guisinger claims awareness for this causal influence can help treat and encourage parents to be more compassionate to children (+)
Doesnt explain low recovery rates (-)
How have the symptoms been passed on (-)
Behavioural Explanation of Anorexia
Anorexia is learned from the environment. Classical Conditioning- Association between eating and anxiety, Operant Conditioning- Reinforcement of dieting/weight loss (Bullying-neg reinforcement, compliments-pos reinforcement), Social Learning Theory- Observation of slim models being admired or overweight people being pnished.
Barlow & Durand (1995) found that over half of contestants in Miss.America contest were 15% or more below the expected body weight for their height.
Fearn (1999) Case study on Fijian women, who didnt recieve Western Tv till 1995. But by 1998 74% of young women on the island said they were too big etc, and eating disorders previously unknown on the island begun to appear.
Eysenck & Flanagan (2000) point out that whilst virtually all young women in the West are exposed to the media only 3-4% of them develop an eating disorder.
Groesz et al (2001) Reviewed studies and found that the ideal portrayed in the mass media causes body dissatisfaction and contributes to the development of an eating disorder.
Psychodynamic Explanation of Anorexia
Disorders are a manifestation of repressed emotional problems. The symptoms of eating disorders symbolise repressed conflicts and motives in the unconscious mind.
Wonderlich et al (1996) Surveyed 1099 American women and found women with a history of sexual abuse had elevated risks of eating disorder symptoms.
Romans et al (2001) Found early maturation and parental over-control were risk factors in AN, and that these factors are a specific concern after the experience of childhood sexual abuse.
Cognitive Explanation of Anorexia
Cognitive errors in Eating Disorders- All or nothing thinking, Overgeneralising, Magnifying/Minimising and Magical Thinking.
Fallon & Rozin (1985)- Male and female students rated themselves on current and ideal body shape. Compared to males, females rated themselves as heavier than what was attractive, and much heavier than ideal.
McKenzie et al (1993)- Female ED patients overestimated their own body size in relation to other women. They judged their ideal weight to be lower than comparable to non-ED patients. Following a sugary snack they judged their body size to have increased whereas controls didnt.