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Lecture 10


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Simon Fraser University
PSYC 100
Sherri Atwood

1 Motivation and Emotions Motivation is a process that influences direction, persistence, and vigour of goal-directed behaviour Perspectives on Motivation: Evolutionary Perspective – innate instincts motivate our behaviour • Problem with Instinct Theory – Circular Reasoning – Why are people greedy? Greed is an instinct. How do we know greed is an instinct? Because people are greedy • Move towards how heredity motivates people; genetic adaptation account Instinct Theory – Do instincts direct human behaviour? • An instinct is a fixed pattern of behaviour that is not acquired by learning and is likely to be rooted in genes and the body ((eg. nesting – homes, bird’s nests)) • Has given way to genetic, hereditary accounts and evolutionary accounts Instincts + Evolutionary perspective – other species have genetically programmed instincts “motivating” their actions • Human babies show reflexes, but in general, our behaviour is less prescribed by genetics than other animals. We may, however, have general patterns of behaviour which can be explained through emerging natural selection Drive-Reduction Theory – Idea that humans are motivated to reduce their drives ((eg. “I eat to reduce hunger.” This restores homeostasis , a steady internal state)) • A drive is an aroused/tense state related to a physical need such as hunger or thirst • Problem – “Seeking Optimum Arousal – we often act in ways to increase arousal. eg. “I love horror movies!” Expectancy X Value Theory – How much you expect studying will lead to an “A,” and how much you value “A’s.” • Expectation that a behaviour will lead to a goal • Incentive value or the value the individual places on the goal Motivation = Expectancy X Incentive Value Incentive Theory – Drives “push” and incentives “pull” • Drives are based on inner needs and can be seen as a force “pushing” from inside us ◦ internal need or drive to have food, or money we can exchange for food • Incentives are external stimuli that either appeal to our needs or trigger our aversive feelings, and can be used to “pull” us in our actions ◦ employers can use the prospect of a raise or elimination of salary as an incentive for us to follow employer goals and policies • Problem – people responds differently to the same incentive Why do people respond differently to the same incentive? • Extrinsic Motivation – Perform activity to obtain external reward or avoid punishment • Intrinsic Motivation – Perform activity for its own sake, you enjoy it Incentives can decrease motivation – Over-justification Hypothesis • Extrinsic rewards for things once enjoyed for their own sake is now like doing work ◦ it’s hard to go back to just enjoying 2 Motivation and Emotions Hierarchy of Needs/Motives: Self Determination Theory – People are most satisfied when they can satisfy: • Competence – a need to master new challenges • Autonomy – a need to experience our actions as free choice • Relatedness – a need to be close to others HUNGER: Metabolism – body’s rate of energy use; 2/3 of energy we use goes to support basal metabolism, the continuous work of body cells To regulate energy – short-term signals (produce hunger and satiety) & long-term signals based on body fat. Signals adjust appetite and metabolism to compensate for overeating and eating too little Regulating Weight: • Set point – when a person’s weight drops or increases, the body responds by adjusting hunger and energy use to being weight back to its initial stable amount ◦ Idea is that most mammals, without consciously regulating, have a stable weight to which they keep returning ◦ a person’s set point might rise with age, or change with economic or cultural conditions ◦ more of a current but temporary “settling point” • In some cases, the set point of a person’s body weight drifts from a healthy weight ◦ Psychological disorders of eating (anorexia) can override this et point, ignore biological signals and lead to extreme weight loss ◦ In other cases, the set point seems to drift upward. Biological tendencies can lead to increased weight that is hard to lose, leading to obesity Is hunger produced by hunger pangs? – Feeling hungry causes stomach contractions, but the feeling can happen even if the stomach is removed or filled with a balloon 3 Motivation and Emotions Receptors throughout the digestive system monitor levels of glucose and send signals to the hypothalamus in the brain • The hypothalamus can send out appetite stimulating hormones, and later, after eating, appetite- suppressing hormones Stomach distention is a sign that you are full • The intestines release peptides that help terminate a meal ◦ CCK is released into bloodstream by small intestines • Brain receives this signal and we decrease eating • People who had stomachs removed still have satiety signals because of hormones Fat cells are regulating food intake and weight by secreting leptin, a hormone that decreases appetite • Gaining fat = more leptin secretion ◦ Tend to eat less because these mealtime satiety factors make us feel full sooner • Leptin signals influence neural pathways to decrease appetite and increase energy expenditure Mice with no OB (obesity) gene mutation lack leptin • Brain does not receive “reduce eating” signal and they get fat Other mice produce leptin by a mutation of dbgene makes their brains insensitive to leptin • The “curb your eating” signal is there but they can’t detect it and get fat Few links to human obesity except in rare cases Eating also depends in part on situational influences • Social facilitation – the presence of others accentuates our typical eating habits • Unit bias – we way eat only one serving/unit of food, but will eat more if the serving size is larger • Buffet effect – we eat more if more options are available Taste Preferences: • Some taste preferences are universal ((eg. carbohydrates – temporarily raise levels of serotonin, reducing stress and depression)) • Other tastes are acquired and become favourites through exposure, culture, and conditioning • Different cultures encourage different tastes Differences in taste preferences are not arbitrary. Personal and cultural experience, influenced by biology, play a role. • We can acquire a food aversion after just one incident of getting suck after tasting a food. • It is adaptive in warm climates to develop a taste for salt and spice, which preserve food • Disliking new tastes may have helped to protect our ancestors Influences on Eating Behaviour • Biological influences – hypothalamic centers in the brain monitoring appetite, appetite hormones, stomach pangs, weight set/settling point, attraction to sweet and salty tastes, adaptive wariness toward novel foods • Psychological influences – sights and smell of food, variety of foods available, memory of time elapsed since last meal, stress and mood, food unit size • Social-cultural influences – culturally learned taste preferences, responses to cultural preferences for appearance Obesity refers to an amount of body fat that increases the risk of health problems to the point that weight loss is a health priority • Obesity is linked to diabetes, heart problems, arthritis, and some cancers 4 Motivation and Emotions Having some body fat is normal and healthy; fat stores energy effectively for later use Body fat has been seen as a sign of affluence, and thus has been considered attractive Standards vary in different cultures, sometimes creating an unhealthy norm of being overweight or underweight Being mildly overweight is not considered a problem if the person is in good physical condition or exercising Heredity influences whether we tend to store energy as fat or lean tissue • Genetics may account for 40%-70% of variation in body mass amongst women and men • But genes are far from the whole story Social Psychology of Obesity • Discrimination based on weight has been found to be stronger than race and gender discrimination ◦ Actors were seen as less employable when made to look heavier ◦ Even children are prejudiced against the overweight • Perhaps as a result, people who are obese are more likely to be depressed or isolated Genetics and Obesity • Adopted siblings eating the same meals end up with BMI similar to biological parents • Identical twins have similar weights, even when raised apart with different food • There seem to be many genes with effects on weight Lifestyle Factors and Obesity • People who are restless and fidgeting burn off more calories and gain less weight than others • Inadequate sleep causes weight gain, despite increased active time, because of appetite hormones • Having an obese friend correlates with becoming obese • Sedentary lifestyles and fast food may be leading to increased body fat worldwide. Obesity and Weight Control • It was adaptive for our ancestors to crave energy-rich food when available ◦ Problem – energy-rich “junk” food is now easily available, and cheaper than healthy • It is adaptive to slow down our burning of fat when food is scarce ◦ Problem – in crash diets, our body can slow down weight loss Physiology of Obesity – Once a person is obese, losing weight is not so easy as “just eating less” • Fat has a lower metabolic rate than other tissue, so a person might gain weight when eating “normally” • Eating less to lose weight slows metabolism – this prevents weight loss, and ensures weight gain when returning to a normal diet • Even if weight loss succeeds, a formerly obese person will have to eat less than an average person just to prevent weight gain 5 Motivation and Emotions EMOTIONS: People can strive to succeed for 2 opposing reasons • Fear of Failure – have strong performance-avoidance goals; they perform well so not humiliated. Fear inhibits best performance, can’t think well • Motivation to Succeed – Focus on mastery of goals which require intrinsic motivation, thrill
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