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PSYC 2020 Lecture Notes - Motivation, Human Body Temperature, Reinforcement

Course Code
PSYC 2020

of 7
Chapter 13- Motivation & Emotion
Motivation - a general term for a group of phenomena that affect the nature, strength, or persistence of an
individual’s behaviour
oa driving force that moves us to a particular action
includes two types of phenomena,
ostimuli that have become associated with pleasant or unpleasant events motivate approach or
avoidance behaviours
many approaches to motivation: physiological, behavioural, cognitive, and social
three important categories of motivated behaviours: eating, sexual behaviour, and aggression
oimportant to the survival of the individual & of the species
situations that motivate our behaviour also provoke emotions
What is Motivation?
We are motivated to perform a behaviour to gain a reinforcer or to avoid a punisher
Biological Needs:
Regulatory Behaviours - a behaviour that tends to bring physiological conditions back to normal, thus
restoring the condition of homeostasis (eg. Eating, drinking, hunting, shivering, etc)
oComplex organisms possess physiological mechanisms that detect deficits or imbalances and restore
the organism to its full potential
Homeostasis - process by which important physiological characteristics (such as body temperature and blood
pressure) are regulated so that they remain at their optimum level
Deficits or imbalances motivate us because they cause us to perform appropriate regulatory behaviours
Regulatory system has FOUR essential features: system variable, set point, detector, and correctional
oSystem Variable - variable controlled by a regulatory mechanism; for example, temperature in a
heating system
oSet Point - optimum value of the system variable in a regulatory mechanism; set point for human body
temperature, recorded orally, is approximately 37 degrees Celsius
oDetector - in regulatory process, a mechanisms that signals when the system variable deviates from its
set point
oCorrectional Mechanism - a regulatory process, the mechanisms that is capable of restoring the
system variable to the set point
Negative Feedback - process whereby the effect produced by an action serves to diminish or terminate that
action; Regulatory systems are characterized by negative feedback loops
ois an essential characteristic of all regulatory systems
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
Drive - a condition, often caused by physiological changes or homeostatic disequilibrium, that energizes an
organism’s behaviour
oAct of eating reduces hunger, and this drive reduction is reinforcing
An individual can survive without sexual behaviour; but sex drive is certainly motivating, and sexual contact is
certainly reinforcing
Many events that we experience as reinforcing are also exciting or drive increasing
Experiences that we really want to repeat are those that increase, rather than decrease our level of arousal
Physiology of Reinforcement:
Electrical stimulation of parts of the brain can reinforce an animal’s behaviour
Electrical stimulation of the brain is reinforcing because it activates the same system that is activated by
natural reinforcers & by drugs that people commonly abuse
oFunction is to strengthen the connections between neurons that detect discriminative stimulus and the
neurons that produce operant response
Optimum-Level Theory:
Removal or avoidance of an aversive stimulus produces negative reinforcement
Optimum-Level Hypothesis - hypothesis that organisms will perform behaviour that restores the level of
arousal to an optimum level
When an individual’s arousal level is too high, less stimulation is reinforcing, when it is too low, more
stimulation is desired
Two forms of exploration related to arousal: Diversive Exploration & Specific Exploration
oDiversive Exploration- is a response to understimulation (boredom) that increases the diversity of the
stimuli the organism tries to come in contact with
oSpecific Exploration- is a response to overstimulation (usually because of a specific need, such as lack of
food or water) that leads to the needed item, thereby decreasing the organism’s drive level
At optimum level of arousal: mid-range behaviour is organized and effective
oIncreasing arousal will produce increasingly effective behvaiour
Too little arousal in the suboptimal range: leads to ineffective behaviour because the person is not sufficiently
Too much arousal outside optimal range: leads to disorganized & ineffective behaviour
Perseverance - the tendency to continue to perform a behaviour even when it is not being reinforced
oThey continue to perform even though their work is not regularly reinforced
When an organism’s behaviour is no longer reinforced, behaviour eventually ceases, or extinguishes
If behaviour is previously reinforced every time it occurred, extinction is very rapid
However, if it was previously reinforced only intermittently, behaviour persists for a long time
oIntermittent reinforcement leads to perseverance, even when the behaviour is no longer reinforced
Extrinsic rewards - those that originate outside oneself
Intrinsic rewards - those that originate inside oneself
Overjustification Hypothesis - the superfluous application of extrinsic rewards to intrinsically motivated
behaviour will undermine intrinsic motivation
oNet result is a loss of intrinsic motivation
oEx: if a person has become motivated by extrinsic rewards and those rewards are no longer available,
the person will no longer be motivated and we will witness a decrease in perseverance
Learned Helplessness - a response to exposure to an inescapable aversive stimulus, characterized by
reduced ability to learn a solvable avoidance task; thought to play a role in the development of some
psychological disturbances
oHelplessness training lowers their expectation that trying to perform a task will bring success
need to eat shaped the evolutionary development of our species
motivation to eat is aroused when there is a deficit in the blood's supply of nutrients and is satisfied by a meal
that replenishes this supply
people who exercise more, use up stored nutrient faster and so must eat more
What Starts a Meal? - Physiological Factors
physiological factors are responsible for eating
Cannon and Washburn suggested that hunger results from an empty stomach
the walls of an empty stomach rub against each other producing hunger pangs
thirst was produced by a dry mouth - “spit and rumble theory”
removal of stomach does not abolish hunger pangs
patients were interviewed whose stomachs were removed and their esophagi were attached directly
to their small intestines
these patients still felt hunger
depletion of a body's store of nutrients is a more likely cause of hunger
glucose is primary fuel for cell
short-term reservoir stores carbohydrates (glucose is converted to glycogen and then stored) – located in the
cells of the muscles and the liver
long-term reservoir stores fats – consists of adipose tissue – found beneath the skin and in various locations
adipose tissue consists of cells capable of absorbing nutrients from the blood, converting them to
triglyceride (fats) and storing them
keeps us alive during prolonged fasts
once glycogen level is low in short-term reservoir, fat cells break down fats and release fatty acids
and a carbohydrate called glycerol
brain lives on glucose and body lives on fatty acid
glycerol is converted to glucose so brain continues to be nourished
difference between obese and normal weight person is the size of their triglycerides
Glucostatic hypothesis – hunger occurs when the level of glucose in the blood becomes low
decrease in blood sugar is detected by glucose-sensitive neurons in the brain called “glucostats”
these detectors activate neural circuits that make a person hungry
there are 2 types of nutrient detectors in the liver that measure the blood level of 2 primary nutrients, glucose
and fatty acids
only activated in extreme cases when blood nutrient levels are severely depleted
Cultural and Social Factors
hunger can wax and wane according to a learned schedule
environment affects hunger (ie. If we are with people who are eating then we will eat)
What Stops a Meal?
an hour passes before nutrients are absorbed from the intestines into the bloodstream
primary cause of satiety is a full stomach
satiety is caused by entry of a sufficient quantity of nourishing food into the stomach
stomach must contain detectors that sense the presence of food and the chemical nature of its contents
rats were allowed to eat until they were filled, some food was taken out of their stomach and were fed again,
the rats ate approximately the same amount of food that was taken out
chemical nature of food is important because if the food is nutritious eating will stop sooner
some rats were ingested with milk while some where ingested with water, the ones ingested with milk
ate a lot less when fed 30minutes later
direct infusion of glucose to hepatic portal reduced reduced how much and how long rat ate
ob mouse has a low metabolism, overeats and gets really fat
ob gene, produces a protein called leptin
Leptin - secreted by fat cells that have absorbed a large amount of triglyceride; acts on hypothalamus
to inhibit hunger
ob mice are unable to secrete leptin
if ob mice are given daily injections of leptin (even to the brain), their metabolism, body temperature
and activity increase and so regain normal weight
14.9% of adults between 20 and 64 are obese
4-5 years after participating in a 15-week weight-loss program, fewer than 3% managed to maintain the weight
loss they achieved during the program
repeated bouts of weight loss and weight gain make future weight loss more difficult
metabolic factors play an important role in obesity
Metabolism – the physiological processes that take place in an organism
people with an efficient metabolism have calories eft over to deposit in long-term reservoir making them more
vulnerable to become obese
people with inefficient metabolism can eat a lot without getting fat
obese people secrete leptin but have efficient metabolisms and overeat
in order for leptin to reduce weight, brain must contain functioning leptin receptors
some people do not respond normally to the presence of leptin in blood
overgrown fat cells secrete high levels of leptin, but the effect the hormone produces in the brain is less intense
than normal, so people overeat
Anorexia Nervosa and Bulimia Nervosa
Anorexia nervosa – disorder characterized by a severe decrease in eating
have an intense fear of becoming obese
exercise constantly
a lot due to media
suffer from osteoporosis, stop menstruating
loss of brain tissue
Bulimia nervosa – disorder characterized by a loss of control of food intake
gorge themselves with food
then induce vomiting or use laxatives
Effects of Sex Hormones on Behaviour
sex hormones, secreted by testes and ovaries have effects on cells all over the body that promote reproduction
these hormones cause production of sperm, build up lining of uterus, trigger ovulation, and stimulate
production of milk
also effect nerve cells in brain, affecting behaviour
sex hormones DON’T CAUSE behaviours
sex hormones affect people’s motivation to act in reproductive way
Effects of Androgens
androgens such as testosterone important for male sexual development
testosterone causes male sex organs and brain to develop
prenatal effects of sex hormones aka organizational effects because they alter organization of sex organs