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PSY210H1 Lecture Notes - Prefrontal Cortex, Appeasement, Adipose Tissue

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Chapter 13: Motivation and Emotion
James Olds and Milner- 1954, discovered pleasure centre in brain of rats through
electrical stimulation lever
Motivation: a general term for a group of phenomena that affect the nature,
strength, or persistence of an individual behaviour
Common definition: driving force that moves us to a particular action
Stimuli that have become associated with pleasant or unpleasant events
motivate approach/avoidance behaviours
Deprivation of a reinforcer increases organisms preference for a particular
There are physiological, behavioural, cognitive and social approaches to motivation
People have motivation to gain a reinforcer or avoid a punisher
Regulatory Systems
Regulatory behaviours: tends to bring physiological conditions back to normal,
thus restoring the condition of homeostasis
Homeostasis: process which physiological characteristic (body temperature, blood
pressure) are regulated so that they remain at their optimum level
4 features of System
1. System variable: variable controlled by regulatory mechanism (temperature in a
2. Set point: optimum value for system variable (22.5 degrees C)
3. Detector: Mechanism that signals when system variable deviates from set point
4. Correctional mechanism: capable of restoring the system variable to set
point(heater turns on when temp goes below 22.5, or off when it goes above)
Negative Feedback: a process whereby the effect produced by an action serves to
diminish or terminate that action. Regulatory systems are characterized by negative
feedback loop.
Drive Reduction Hypothesis:
the hypothesis that a drive produces an unpleasant state that causes an
organism to engage in motivated behaviours (hunger is a drive that produces
an unpleasant state caused by going without food for a long time, cause one to
engage in behaviours that will lead to food)
reduction of drive is assumed to be reinforcing (Eating is a drive reducing act,
and is reinforcing)
biological needs, caused by deprivation of necessities of life are unpleasant
hypothesis is disfavoured b/c drive is impossible to measure, and b/c events we
experience as reinforcing are also exciting or drive increasing
in general: the experiences we really want to repeat are those that increase
our level of arousal
Physiology of Reinforcement
neural circuits stimulated by electricity are also responsible for the motivating
effects of natural reinforcers such as food, water, or sexual contact, and drugs
such as cocaine or alcohol.
Essential component of reinforcement system is neurons that release
dopamine as their transmitter substance
Optimum level theory
Optimum level hypothesis: organisms will perform behaviour that restores the
level of arousal to an optimum level
Attempt to explain positive and negative reinforcement
When arousal is too high, less stimulation is reinforcing and vice versa
Diversive exploration: response to understimulation (boredom) that increases the
diversity of the stimuli the organism prefers
Specific Exploration: response to overstimulation that leads to the needed item,
decreasing drive level
Hebb studied arousal’s affect on effectiveness of behaviour
Optimal arousal organized effective behaviour
Suboptimal ineffective due to insufficient motivation
Too much arousal disorganized therefore ineffective
Problem with theory is again that drive cannot be measured, so can’t say what
optimum level is
Perseverance: tendency to continue to perform a behaviour even when it is not
being reinforced, well motivated
Effect of intermittent punishment
behavior usually ceases when it is no longer reinforced
if previously reinforced every time, extinction is rapid, if intermittently
reinforced, behaviour persists (perseverance)
previous experience with various schedules of reinforcement affects
Effects of unnecessary reinforcement
Extrinsic rewards: those that originate outside oneself
Intrinsic rewards: originate inside oneself
Being paid to get good grades causes children to be motivated by extrinsic
rather than intrinsic rewards
Overjustification Hypothesis: superfluous application of extrinsic rewards to
intrinsically motivated behaviour will undermine intrinsic motivation loss in
intrinsic motivation
After shift from intrinsic to extrinsic reinforcement, and extrinsic rewards
disappear, the person will show what amounts to a loss of interest and
perseverance in the reinforced activity
Lepper Greene and Nisbett(1973)
Experiment confirming overjustification hypothesis
Children drawing during play time (intrinsically motivated activity) subject
to 3 conditions
1) Child asked to make drawing for a prize ( extrinsic reward)
2) Child asked to make drawing, and unexpectedly received prize
3) Child neither offered nor given prize for making drawing
After the study there was less intrinsic motivation to draw in children from 1st
group, compared to 2nd and 3rd groups, who were still intrinsically motivated
The fact that 2nd group was still intrinsically motivated shows that expectation
of a reward is what affects behaviour
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
organisms can learn that they have no control over their destiny
Maier and Seligmen(1976)
Experiments demonstrating that animals can learn that behaviour doesn’t
affect environmental events
Dog placed in apparatus where it received electric shocks that could not be
avoided, then placed the dog in an apparatus where electric shock was
preceded by warning (shock could be avoided by stepping over barrier to other
Dogs in control group learned to avoid the shock, but if dog previously received
inescapable shocks it failed to learnlearned to be helpless
Implications: when people have experiences leading to helplessness lowered
expectation that trying will lead to success
Learned helplessness has characteristics of personality traitpeople with
history of learned helplessness will stop trying in other aspects of life
Need to eat shaped evolutionary development of our species
Causes of hunger
Physiological factors body needs nourishment
Canon and Washburn(1912)
ohunger results from empty stomach, thirst from dry mouth (spit and
rumble theory), but people without stomachs still feel hunger
Depletion of nutrients is more likely cause glucose and fatty acids
Short-term reservoirin liver and muscles
When glucose is eaten, some is used for fuel, and rest is converted to glycogen
and stored in liver