Slides

PsychExchange.co.uk Shared Resource

Description
1. Biological explanations of eating behaviour <ul><li>Neural mechanisms in eating and satiation </li></ul><ul><li>Evolutionary…
Categories
Published
of 20
All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.
Related Documents
Share
Transcript
  • 1. Biological explanations of eating behaviour <ul><li>Neural mechanisms in eating and satiation </li></ul><ul><li>Evolutionary explanations for food preferences </li></ul>
  • 2. To begin with... <ul><li>Hunger is activated by many different cues, both biological and environmental </li></ul><ul><li>All animals have a motivation to eat and this motivation increases as energy level decrease </li></ul><ul><li>An imbalance occurs when the energy expended exceeds the energy consumed; this imbalance is signalled to the brain in a number of different ways... </li></ul>Dieting
  • 3. neural mechanisms <ul><li>‘ Hunger pangs’ lead to eating, so does the motivation to eat come from a peripheral signal in the stomach? (Walter Cannon, 1927) </li></ul><ul><ul><li>Cannon and Washburn – a balloon experiment... </li></ul></ul><ul><li>No , the stomach mediates, but more importantly, neural mechanisms are involved in making the decision when and when not to eat (Karl Lashley, 1938) </li></ul><ul><ul><li>Main hunger centre – the lateral hypothalamus </li></ul></ul><ul><ul><li>Main ‘satiety centre – the ventromedial hypothalamus </li></ul></ul>Dieting
  • 4. Physiological Research: <ul><li>Cannon and Washburn (1912) found that stomach </li></ul><ul><li>contractions (pangs of an empty stomach) apparently do happen when we are hungry. </li></ul>But, patients without stomachs still get hungry. So hunger actually comes from the brain and not the stomach
  • 5. Hunger, Eating and Satiation: the process Eating stops Blood glucose levels drop Lateral hypothalamus activated Hunger develops Satiety reached Ventromedial hypothalamus activated Increase in blood glucose Eating
  • 6. Make and fill this table (AO1) notes: p82 <ul><li>Neural control of Cognitive Factors </li></ul><ul><li>The Lateral Hypothalamus </li></ul><ul><li>The Ventromedial Hypothalamus </li></ul><ul><li>Homeostasis </li></ul>
  • 7. Make and fill this table (AO2/3) notes: p83 <ul><li>Real World Application </li></ul><ul><li>Stress & Hunger </li></ul>The Role of the Ventromedial Hypothalamus The Role of the Lateral Hypothalamus Neural Control of Cognitive Factors The Role of Neuropeptide Y Limitation Homeostatic Explanation
  • 8. Assignment 2 <ul><li>2. Discuss/evaluate ways in which eating/satiation are controlled by neural mechanisms(25 marks) </li></ul><ul><li>Instructions: </li></ul><ul><li>The essay style answer should have an Introduction (introduce/define). Then AO1 (9 marks) and AO2/3 (16 marks) as sub-headed sections followed by a short conclusion (summary). You WILL need to focus on AO2/3 (check ‘commentary’ and chapter summary pp 94-95 textbook). </li></ul><ul><li>Ideally word processed (1 to 1.5 A4 or 500/600 words). </li></ul><ul><li>Email to me on: [email_address] </li></ul>
  • 9. Next… <ul><li>Evolutionary explanations for food preferences </li></ul>
  • 10. <ul><li>The “ultimate explanation” </li></ul><ul><li>Eating behaviour that might not make sense today may have an evolutionary basis... </li></ul><ul><li>Our ancestors lived in an </li></ul><ul><li>Environment of Evolutionary </li></ul><ul><li> Adaptation (EEA) era </li></ul><ul><li>Natural selection favoured </li></ul><ul><li>adaptations geared </li></ul><ul><li>towards survival </li></ul>
  • 11. Evolutionary explanations of food preferences <ul><li>Evolutionary theory suggests that organisms should behave so as to maximise survival and successfully reproduce to pass on their genes (Barash, 1977). </li></ul><ul><li>Survival depends on number of things, one of which involves remaining healthy by managing to obtain sufficient nutrients to meet demands of the body </li></ul>
  • 12. Preference for high-calorie food <ul><li>It was adaptive for humans to learn which foods have high nutritional value (high-calorie), since calories are essential to provide energy for the body to function </li></ul><ul><li>Those humans who learnt quickest which foods would provide the most nutrition were the most likely to survive and reproduce . </li></ul>Evolutionary explanations
  • 13. <ul><li>Davis (1928,1939) observed choices of children living in a paediatric unit </li></ul><ul><li>Found that young children had an innate , regulatory mechanism and make healthy food choices </li></ul><ul><li>BUT they could only do so if healthy food was actually available!!! </li></ul><ul><li>So food choice changed over time based on the environment </li></ul>
  • 14. Preference for sweet foods <ul><li>A sweet taste is often associated with ripeness, a high concentration of sugar and a quick fix of calories </li></ul><ul><li>A preference for sweet food/drinks that would encourage consumption of ripe fruit was probably advantageous to our early ancestors (Rozin, 1982 ) </li></ul>Evolutionary explanations
  • 15. Preference for salty foods <ul><li>Salt is essential for the body to function properly </li></ul><ul><ul><li>Infants about four months old seem to show a marked preference for salty foods over non-salty </li></ul></ul><ul><ul><li>At the age of two years, children reject foods that do not contain the expected amount of saltiness (Beauchamp, 1987) </li></ul></ul>Evolutionary explanations
  • 16. <ul><li>Desor et al (1975) investigated babies food preferences based on facial expressions and sucking behaviour </li></ul><ul><li>Newborn babies demonstrate innate preference for sweet tasting food </li></ul><ul><li>Babies reject bitter tasting substances </li></ul>
  • 17. <ul><li>Sweet food = fruit = natural fructose content = energy </li></ul><ul><li>Bitter = poison </li></ul><ul><li>Neophobia = fear of new foods (unknown =>possibly dangerous) </li></ul>
  • 18. <ul><li>-Reductionist and determinist (eating is caused by events happened years ago) </li></ul><ul><li>+can explain innate food preferences </li></ul><ul><li>+gives an explanation that can account for both nature and nurture </li></ul><ul><li>-difficult to falsify, so questionable validity </li></ul><ul><li>+focus on ultimate rather than proximate causes could provide more effective intervention strategies </li></ul><ul><li>-has human evolution stopped or are we still adapting? </li></ul>
  • 19. Summary of explanations/commentary: <ul><li>Read and make notes p84 for explanations (AO1) </li></ul><ul><li>Read and make notes p85 for commentary analysis (AO2/3) </li></ul>
  • 20. Assignment 3 <ul><li>3. Discuss two or more evolutionary explanations of food preference (25 marks) </li></ul><ul><li>Instructions: </li></ul><ul><li>The essay style answer should have an Introduction (introduce/define). Then AO1 (9 marks) and AO2/3 (16 marks) as sub-headed sections followed by a short conclusion (summary). You WILL need to focus on AO2/3 (check ‘commentary’ and chapter summary pp 94-95 textbook). </li></ul><ul><li>Ideally word processed (1 to 1.5 A4 or 500/600 words). </li></ul><ul><li>Email to me on: [email_address] </li></ul>
  • We Need Your Support
    Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

    Thanks to everyone for your continued support.

    No, Thanks