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Chapter 13

Midterm Notes Chapter 13.docx

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University of Toronto Scarborough
Steve Joordens

Midterm Notes Chapter 13 – Motivation and Emotion Motivation: general term for a group of phenomena that affect the nature of strength, and persistence of an individual’s behaviour This chapter focuses on eating, sexual behaviour and aggression as these are important to survival of individual and species WHAT IS MOTIVATION Motivation is proactive and reactive Biological Needs Complex organisms possess physiological mechanisms that detect deficits or imbalances associated with these needs and related Regulatory behaviours: behaviour that tends to bring physiological conditions back to normal, thus restoring the condition of homeostasis Homeostasis: process by which important physiological characteristics are regulated so that they remain at their optimum level Regulatory system has 4 essential features: System variable: variable controlled by a regulatory mechanism for example temperature in a heating system Set point: optimum value of the system variable in a regulatory mechanism Detector: In a regulatory process, a mechanism that signals when the system variable deviates from its set point Correctional Mechanism: the mechanism that is capable of restoring the system variable to the set point Negative Feedback: process where the effect produced by an action serves to diminish or terminate that action. Regulatory systems are characterized by negative feedback loops Earliest systematic attempt to explain nature of motivation and reinforcement was: Drive reduction hypothesis: hypothesis that a drive (resulting from physiological need or deprivation) produces an unpleasant state that causes an organism to engage in motivated behaviours. Reduction of drive is assumed to be reinforcing. Example: Hunger, Hunger serves as a drive: condition caused by physiological changes or homeostatic disequilibrium that energizes an organism’s behaviour The act of eating reduces hunger and this drive reduction is reinforcing Not all dives are based on homeostasis; example o sex drive, we can survive without sex but the drive is certainly motivating, and is reinforcing Also, organisms in a featureless environment will be motivated to seek for something new This hypothesis falls in disfavor for two primary reasons: drive is almost impossible to measure & if we examine our own behaviour we find many events we experience are also exciting or drive increasing; roller coasters is fun not because it reduces drive Generally experiences we want to repeat, increase, not decrease our level of arousal/drive Physiology of Reinforcement Olds and Milner – showed electrical stimulation of brain can be reinforcing to rats, found that it is reinforcing because it activates same system that is activated by natural reinforcers. Essential part of reinforcement system consists of neurons that release dopamine as transmitter substance Optimum-Level Theory In some cases, motivation can be avoidance of exciting stimuli Some psychologists proposed optimum-level hypothesis of reinforcement and punishment: hypothesis that all organisms will perform behaviour that restores the level of arousal to an optimum level Berlyne proposed two forms of exploration related to arousal – Diversive exploration [ response to under stimulation] and Specific Exploration [response to over stimulation] Problem – since we cannot measure someone’s drive we cannot determine what the optimum level is Perseverance Perseverance: the tendency to continue to perform a behaviour even when it is not being reinforced. Effects of Intermittent Reinforcement Studied in various ways: withholding of reinforcers, reinforcement of competing behaviour and so on Behaviour acquired with intermittent reinforcement more resistant to extinction Succeeding after several failures can cause the learner to resist the effects of subsequent failures Discovered in studies of extinction that environmental stimuli present during extinction become aversive Motivational effects of extinction are called frustration, and if another animal or human is present during the extinction they may be attacked -this s called extinction-induced aggression Example: quiet office worker who pounds on the vending machine when it doesn’t give him his candy bar In society; large scale example would be scapegoating Overjustification Hypothesis Some psychologists suggest providing extrinsic rewards for behaviour that is already maintained by intrinsic rewards may weaken target behaviour Overjustification hypothesis: superfluous application of extrinsic rewards to intrinsically motivated behaviour will undermine the intrinsic motivation Lepper, Greene, Nisbett – carefully documented free-play activities of kids in daycare, among favorites was drawing on paper. Two weeks after, randomly assigned children one of three conditions: draw to win a prize, no extrinsic reward offered but received same prize, and neither offer nor given the prize Children offered the prize 2 weeks later when alone were less inclined to draw, while the other groups were just as likely as before to draw Learned Helplessness Learned Helplessness: response to exposure to an inescapable aversive stimulus, characterized by reduced ability to learn a solvable avoidance task; thought to play a role in development of some psychological disturbances Overmier and Seligman – dogs with shock-floor experiment Human Applications – when humans are in an experience which they are powerless to control the events that happen to them, they may become depressed and their motivational level may decrease EATING Regulation and expression of eating is one of most complex motivated behaviours What Starts a Meal Physiological Factors Reasons for starting a meal must somehow be related to the fact that the body needs nourishment Cannon and Washburn – proposed eating begins with an empty stomach (walls of stomach can rub together to create hunger pangs) but even with removal of stomach, patients still felt hungry Depletion of body’s store of nutrients is more likely cause of hunger [primary fuels are glucose, and fatty acids] There are two reservoirs that keep our body nourished when our gut is empty (like when we wake up in morning), short term reservoir [stores carbs] and long term reservoir [stores fats] Short term – located in cells of muscles and liver, filled with glycogen: insoluble carb that can be synthesized from glucose or converted to it; used to store nutrients Long Term – the adipose tissue beneath skin in various locations of abdomen – consists of cells capable of absorbing nutrients from blood and converting them to triglycerides (fat) and storing them Long term reservoir keeps us alive during prolonged fasting; once glycogen is depleted, fat cells release fatty acids and carb called glycerol brain cells metabolize glucose and other cells metabolize fat, so brain is nourished even after the short term reservoir is depleted Mayer – Glucostatic Hypothesis: hypothesis that hunger is created by a low level of availability of glucose, a condition that is monitored by sensory neurons. Further research shows this is too simple, eating can be instigated in different ways: -empty stomach causes hormone ghrelin to be secreted which is a potent stimulator of eating -liver contains two nutrient receptors one that detects glucose and another that detects fatty acids, both activate pathways to the brain which initiate eating -brain itself also has similar receptors to initiate eating Cultural and Social Factors For most of us, eating not initiated by just biological means, but by habit such as 3 meals a day/time of day and other environmental stimuli We are also more likely to eat when we are with friends who are eating What Stops a Meal If we were to continue to eat until nutrients entered our blood stream, we would burst, takes about an hour for nutrients to take effect Primary immediate cause of satiety is stimulation of receptors by distended stomach, in experiments with rats, eating doesn’t occur if food is directly into the stomach, and if food is removed from stomach, eating continues unabated Rats were allowed to eat their fill, and once stomach contents were taken out and they were allowed to eat, they ate as much as was removed. Stomach can sense to when it is full Stomach can also sense chemical contents, if food is very nutritious, eating stops relatively soon, but if not, it won’t Rat experiment – injected either milk or salt water into their stomachs, the rats with milk had eaten less after than salt water, so therefore receptors can sense nutrients Duodenum - portion of intestines in which stomach empties secrets hormone called CCK that suppresses eating Liver also detects nutrients, once nutrients enter in blood stream they stimulate liver-receptors Researchers found genetic basis for obesity in rats; mutation in gene called OB that normally produces protein known as leptin, which is secreted by fat cells that have absorbed a large amount of triglyceride and acts on receptors to inhibit hunger, however, the mutant makes it unable to synthesize leptin -Leptin has strong effects on metabolism and eating, if injected their metabolic rates increase, their body temperature rises and they become more active and eat less Maffei – found leptin in human’s blood is correlated with obesity Obesity 14.9% of Canadians between 20-64 are obese (having BMI of 30 or greater) BMI is calculated by weight divided by square of height Mortality rate increases by about 30% for those with a high BMI rate, 40% when really high Wadden and Brownell, Foster, - reported weight reduction of 7 units of BMI combined with 150min of exercise a week reduces likelihood of developing diabetes by 58% Many psychological variables of causes of obesity: relatively low impulses, inability to delay gratification, and maladaptive eating styles (eating too fast) Rodin and colleagues found depression
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