Chapter 10 Flashcards
Drive Theories
Internal state of tension that motivates an organism to engage in activities to reduce this tension. When you experience a drive, you are motivated to reduce it (ex: hunger and eating)
Incentive Theories
External goal with capacity to motivate behaviour-Environmental
Expectancy Value Models
2 factors of ones motivation. 1) Expectancy about one’s chances of obtaining the incentive. 2) Value of desired incentive.
Evolutionary Theories of Motivation
Natural selection favours behaviour that maximizes reproductive success. Motivations of affiliation, dominance, sex drive, etc.
Biological Factors and Hunger-Stomach Contractions
Association between stomach contractions and hunger- Walter Cannon theorized that stomach contractions cause hunger, but people continue to experience hunger even after their stomachs have been removed.
Brain Regulation of Hunger
Hypothalamus-Lateral and ventromedial nucleus of the hypothalamus were brains on-off switches for hunger (Theory was disproven).
Arcuate and Paraventricular Nucleus
Important in hunger regulation-Arcuate is especially important as it contains nerves that are sensitive to oncoming hunger signals and another group for satiety signals.
Contemporary Theories of Hunger
Focuses more on neural circuits than anatomical centres.
Digestive and Hormonal Regulation
Stomach sends signals to the brain to inhibit further eating. (vagus nerve- indicates how stretched stomach walls are).
Ghrelin
Causes stomach contractions and promotes hunger when body is without food for awhile.
CCK
Released from upper intestine after food is consumed which delivers satiety signals to the brain and stops hunger.
Leptin
Contains information about bodies fat stores. High leptin=less hunger. Low leptin= more hunger. Communicates to hypothalamus.
Environmental Factors of Hunger
1) Availability of food, 2) Learned preferences and habits, 3) Stress.
Palatability
The better a food tastes, the more of it people and animals will consume.
Quantity
People tend to consume what’s put in front of them (bin model or bin heuristic).
Variety
People increase their food consumption when there is a variety available Value of food declines as you eat a specific food.
Presence of Others
Individuals eat 44% more when they eat with others. More people makes for more eating. Women eat aless in the presence of opposite sex whom they don’t know well.
Stress
Roughly 40-50% of people increase food intake while stressed, and also eat less healthy foods.
Herman and Polivy
Social norms around eating-exposure to pictures and written descriptions of attractive foods can cause an increase in food intake. Presence of others generally inhibits eating, but under specific conditions may increase it.
Learned Preferences
Preference for sweet tastes is present at birth. Preference for high fat foods may be genetic. Taste preferences are partly a function of learned associations and exposure.
Body Mass Index
Weight in kilograms/height in metres. BMI of 25.0-29.9 is considered overweight, 30+ is obese.
Obesity Stats in Canada
20.2% of Canadians over 18 were reported as obese in 2015. 40% of men and 27.5% of women were classified as overweight. Provinces with the lowest levels of obesity were Quebec and BC.
Theories of Obesity
Historically, humans lived in competitive environments and competed for limitiedd, unreliable food sources. This caused people to overreat when they could to store excess calories for future food shortages.
Genetic Predisposition
Twin Study-Identical twis reared apart had more similar BMI’s than fraternal twins reared together. Genetic factors account for 61%of variation in weight among men, 73% among women.
Eating and Exercise
Unhealthy foods are being consumed more and people also aren’t exercising as much. Children are not meeting current Canadian physical activity guidelines , especially vulnerable to this are girls aaged 12-17.
Set point
Body moniters fat cell levels to keep them and weight stable. Set point is each individuals natural point of stability for weight.
Why is it hard to lose weight and keep it lost?
People burn calories slower, reduced fat stores result in reduced leptin which increases hunger. Body has also been sculpted by evolution to defend against weight loss.