Download doc Chapter 6 Notes

How did the Behavioral Study of Learning Develop? 237
• learning: an enduring change in behaviour resulting from experience
• essence of learning is understanding how events are related (dentist and pain)
• associations develop through conditioning: a process in which environment
stimuli and behavioral responses become connected. 2 types:
• classical conditioning (pavlovian conditioning): a type of learned response
that occurs when a neutral object comes to elicit a reflexive response when
it is associated with a stimulus that already produces that response (a song
in a scary movie makes our hearts beat faster)
• operant conditioning (instrumental conditioning): a learning process in
which the consequences of an action determine the likelihood that it will be
performed in the future (studying leads to better grades)
• freud used report techniques (ie. dream analysis) to assess mental processes that
believed were behaviours primary determinant
• John B. Watson
• believed that things that could not be observed directly (people’s mental
experiences) were not a valid indicator for psychological activity
• founded Behaviorism: a school of thought based on the belief that animals
and humans are born with the potential to learn just about anything
• *states that the environment and its associated effects on animals were
the sole determinants of learning
• based on John Locke’s idea of tabula rasa (blank slate) - states that infants
are born knowing nothing at all and that all knowledge is acquired through
sensory experiences
Behavioral Responses are Conditioned
• Pavlov’s Experiment
• Ivan Pavlov, nobel prize, work on the digestive system > salivary reflex
• salivation at the sight of a person or bowl is not automatic and therefore must have
been acquired through experience
•
•
•
•
neutral stimulus: unrelated to the salivary reflect (ringing bell)
presented with stimulus that reliably produces the stimulus (food)
this pairing, conditioning trial, repeated a number of times
critical trial bell sound is presented alone and reflex is measured
• (UR) Unconditioned Response: a response that does not have to be
learned/reflex - salivation elicited by food
• (US) Unconditioned Stimulus: a stimulus that elicits a response, such as a reflex,
without any prior learning. unlearned and automatic behaviour - food
• (CS) Conditioned Stimulus: a stimulus that elicits a response only after learning
has taken place - ringing bell produces salivation
• (CR) Conditioned Response: a response that has be learned - salivation at
sound of only bell
• the condition and unconditioned responses are salivation but not identical
• conditioned response is usually weaker
• bell produced less saliva that food did
• Acquisition, Extinction, and Spontaneous Recovery
• Pavlov believed that conditioning is the basis for how animals learn to adapt to
their environment
• each time it rained, a delicious and nutritious plant blooms - animals that learn this
association will seek the plant out every time it rains
• acquisition: the gradual formation of an association between stimuli, one
conditioned (rain) and one unconditioned (plant bloom)
• once a behaviour is acquired, how long does it persist?
• animals sometimes have to learn when associations are no longer adaptive
• if bell is presented many times and food does not arrive, animal learns that the
bell is no longer a god predictor of food - salivary responses disappear
• *NOTE: the strongest association occurs when the CS is presented slightly
before the US, because it acts as a predictor. the CS “warns you” of an
upcoming Us
extinction:
a process in which the conditioned response is weakened when the
•
conditioned stimulus is repeated without the unconditioned stimulus
• spontaneous recovery: a process in which a previously extinguished response
reemerges following presentation of the conditioned stimulus
• if the delicious plant blooms during a certain season, the adaptive response is
to check back once in a while to see if it blooms after the rain
• extinction reduces the strength of the associated bond but does not eliminate it
• Generalization, Discrimination, and Second-Order Conditioning
• stimulus generalization: occurs when stimuli that are similar but not identical to
the conditioned stimulus produce the conditioned response
• generalization is adaptive because in the nature of CS is seldom experienced
repeatedly in an identical fashion therefore animals learn to respond to the
variations in the CS
• slight difference in background noise, temperature, lighting etc
• it is also important for animals to distinguish among similar stimuli - 2 plants might
look the same but one is poisonous
• stimulus discrimination: a differentiation between 2 similar stimuli when only one
of them is consistently associated with the unconditioned stimulus
• second-order conditioning: sometimes a conditioned stimulus becomes directly
associated with other stimuli associated with the US
• black square was shown every time bell was rung and soon the black square also
caused salivation
• money > purchasing power > associated with a rewarding feeling
• even though second-order conditioning powerfully influences many of our beliefs
and attitudes, most of it occurs implicitly, without awareness or intention
Phobias and Addictions Have Learned Components
• Phobias and their Treatment
• phobia: an acquired fear that is out of proportion to the real threat of an object or
of a situation
• according to classical-conditioning, phobias develop through the generalization of
a fear experience (person stung by a wasp fears all flying insects)
• fear conditioning: process of becoming classically conditioned to fear an object
• child becomes fearful of rats when loud noise is made every time it is near one
• the classical conditioning was shown to be an effective method of inducing phobia
• counterconditioning: exposing people to a small dose of the feared stimulus
while having them engage in a pleasurable task in order to help people overcome
fear
• Joseph Wolpe’s treatment method of systematic desensitization
• Drug Addiction
• conditioned drug effects are common and demonstrate conditioning’s power
• heroine addicts can feel aroused by the sight of a needle
• can experience withdrawal when cravings can not be satisfied
• Shepard Siegel conducted research showing that drug tolerance effects are
specific to certain situations
• tolerance is a process by which addicts need more and more of a drug o
experience the same effect
• tolerance is greatest when drug is taken in the same location as previous drug use
> body has learned to expect the drug in that location and to compensate for the
drug (by altering neurochemistry of physiology to metabolize it) > addicts are more
likely to overdose when taking drugs in a new setting
Classical Conditioning Involves More Than Events Occurring at the Same Time
• Evolutionary Significance
• according to Pavlov, any object/phenomenon could be converted into a
conditioned stimulus during conditioning trials
• apparently however, not all stimuli are equally effective in producing learning
• certain pairings of stimuli are more likely to become associated than others
• taste and smell is more likely to relate to food than sound or light
• animals are genetically programmed to fear specific objects - biological
preparedness - explains why animals tend to fear potentially dangerous things
• people are more likely to associate negative stimuli with out-group members (ie.
race)
• nazi’s aimed to condition a national repulsion response to jews by creating films in
which jew’s faces were morphed into those of rats crawling in filth
• different types of stimuli cause different reactions even within a species
• Gender Differences in Learning
• behaviours we learn most easily are adaptive in an evolutionary sense
• difference of how men and women learn their way around an environment is
related to hunter-gatherer societies
• women will more-likely use landmarks and memorize a series of terms when
navigating through space
• men will more-likely keep track of cardinal directions (north, south)
• The Cognitive Perspective
• classical conditioning is a means by which animals come to predict occurence of
events
• for learning to take place, the conditioned stimulus must accurately predict the
unconditioned stimulus
• stimulus that occurs before the US is more easily conditioned that one that comes
after it
• Rescorla-Wagner Model: a cognitive model of classical conditioning; it states that
the strength of the CS-US association is determined by the extent to which the
unconditioned stimulus is unexpected
How Does Operant Differ From Classical Conditioning? 249
• many of our actions are instrumental - done for a purpose (buy food to eat it)
• we learn that behaving in certain ways can lead to reward or punishment
• these processes are called instrumental conditioning / operant conditioning
• operant: idea that animals operate on their environments to produce effects
• operant conditioning is the learning process in which an actions’ consequences
determine the likelihood that the action will be performed in the future
Reinforcement Increase Behaviour
• Shaping
• shaping: a process of operant conditioning; it involves reinforcing behaviours that
are increasingly similar to the desired behaviour
• you can not provide the reinforcer until the person or animal displays the
appropriate response
• shaping involves reinforcing behaviours that are increasingly similar to the desired
behaviours more selectively
• to teach a dog to roll over you initially reward any behaviour that is similar to
rolling over > once this behaviour is established you reinforce behaviours
more selectively
• reinforcing successive approximations eventually produces the desired
behaviour by teaching the animal to discriminate which behaviour is being
reinforced
• shaping has been used to teach autistic children language, mentally ill people
social skills
• Reinforcers Can Be Conditioned
• primary reinforcers: reinforcers that satisfy biological needs (necessary for
survival) - food, water
• from an evolutionary standpoint it is essential to learn primary reinforcers organisms that repeatedly perform behaviours reinforced by food and water
are more likely to survive and pass on their genes
• secondary reinforcers: events or objects that serve as reinforcers but so not
satisfy biological needs
• are established through classical conditioning
• money is associated with power
• Reinforcer Potency
• Theory of Reinforcement proposed by David Premack
• theorizes that a reinforcer’s value could be determined by the amount of time an
organism engages in a specific associated behaviour when free to do anything
• ie. ice cream is more reinforcing for children who choose to spend more
time eating ice cream than spinach
• his theory is useful because it can account for differences in individual’s
values
• Premack Principle
• more valued activity can be used to reinforce the performance of a less
valued activity
• eat your spinach and then you’ll get dessert
Both Reinforcement and Punishment Can Be Positive or Negative
• reinforcement and punishment have opposite effects on behaviour
• reinforcement increases behaviour’s probability
• punishment decreases behaviour’s probability
• Positive and Negative Reinforcement
• positive reinforcement: increase in the probability of a behaviour’s being
repeated following the administration stimulus
• sometimes involved reward
• people work harder to get a raise in pay
• negative reinforcement: the increase in the probability of a behaviour’s being
repeated through the removal of stimulus
• rat is negatively reinforced when required to press a lever to turn off an
electric shock
• negative reinforcement differs from punishment
• if being punished, you would receive a shock for pressing the lever
• reinforcement increases the likelihood of behaviour
• punishment decreases the likelihood of behaviour
• ie. close your door to shut out noise, change channel to avoid watching a bad
show
• Positive and Negative Punishment
• punishment reduces the probability that behaviour will recur
• positive punishment: punishment that occurs with the administration of a
stimulus and thus decreases the probability of a behaviour’s recurring
• a rats getting shocked for pressing a lever
• negative punishment: punishment that occurs with the removal of a stimulus and
thus decreases the probability of a behaviour’s recurring
• teens whose driving privileges are revoked for speeding may be less likely
to speed the next time they get behind the wheel
• Effectiveness of Parental Punishment
• for punishment to be effective; it must be reasonable, unpleasant, and applied
immediately so that the relationship between the unwanted behaviour and the
punishment is clear
• physical punishment is ineffective
Operant Conditioning Is Influenced By Schedules of Reinforcement
• continuous reinforcement: a type of learning in which the desired behaviour is
reinforced each time it occurs
• for faster learning
partial
reinforcement: a type of learning in which behaviour is reinforced
•
intermittently
• more common in the real world
• Ratio and Interval Schedules
• partial reinforcement can be administered according to either:
• ratio schedule: a schedule in which reinforcement is based on the number
of times behaviour occurs
• leads to greater responding
• paid by item sold (commission)
• interval schedule: a schedule in which reinforcement is available after a
specific unit of time
• paid by the hour
• Fixed and Variable Schedules
• partial reinforcement can also be given a fixed or variable schedule
• fixed schedule: a schedule in which reinforcement is consistently provided
upon each occurrence
• rate of reinforcement is predictable
• whether factory workers are paid by the hour or by the item, earning
for each item or hour is consistent
• variable schedule: a schedule in which reinforcement is applied at different
rates or at different times
• responder does not know how many behaviours need to be
performed or how much time needs to pass before reinforcement will
occur
• Behavioural Persistence
• continuous reinforcement is effective for teaching a behaviour but if reinforcement
is stopped, behaviour extinguished quickly
• people continue to put money into slot machines at casinos because
sometimes it provides reward > effect is called variable-ratio schedule
• partial-reinforcement extinction effect: the greater persistence of behaviour
under partial reinforcement that under continuous reinforcement
• during continuous reinforcement learner can easily detect when
reinforcement has stopped
• when behaviour is only reinforced sometimes, learner needs to repeat
behaviour to detect absence of reinforcement
• therefore the less frequent the reinforcement during training, the greater the
resistance to extinction
• Behavioural Modification
• behavioural modification: the us of operant-conditioning techniques to eliminate
unwanted behaviours and replace them with desirable ones
• rationale behind this is that most unwanted behaviours are learned therefore can
be unlearned
• be more productive at work, drive more safely
• token economics: gain tokens if your are good, lose them if you are bad
• chimpanzees perform tasks in exchange for tokens that they can use for
food
Biology and Cognition Influence Operant Conditioning
• Biological Constraint
• although behaviourists believed that any behaviour could be shaped through
reinforcement, we now know that animals have a hard time learning behaviours
that run counter to their evolutionary adaptations
• raccoon stopped putting the money into the piggy bank, instead began to treat
it like food and held it and rubbed it
• conditioning is most effective when the association between the behavioral
response and the reinforcement is similar to the animal’s built-in predisposition
• Acquisition / Performance Distinction
• another challenge to the idea that reinforcement is responsible for all behaviour is
that learning can take place without reinforcement
• Edward Tolman argued that reinforcement has more impact on performance than
on learning
• Tolman’s term ***latent learning: learning that takes place without
reinforcement
• takes place in the absence of reward
• just because there is no visible sign of learning, the rats are still learning
• therefore, we cannot always as !!!!
• another for of learning that rakes place without reinforcement is insight learning:
a form of problem solving in which a solution suddenly emerges after a period of
inaction or contemplation of the problem
The Value of Reinforcement Follows Economic Principles
• new approach to understanding operant conditioning considers reinforcement’s
value in the context of basic economic principles such as supply and demand
• short supply is typically more valued and therefore is a more potent reinforcer
• $100 today or $1000 tomorrow
at
the
heart of the behavioural economics approach are 2 ideas: that people and
•
other animals often need to choose between reinforcers and that a particular
reinforcer’s worth is affected by the likelihood of its payoff and how long that payoff
might take
• even a simple behaviour such as eating requires a number of calculations to detect
the costs and benefits associated with different behavioural options
How Does Watching Others Affect Our Learning? 261
• we not only learn things through doing, but also by observing others
• we often acquire attitudes about politics, religion, people, objects etc from outside
sources such as parents, peers, teachers, media
Leaning Can Be Passed on through Cultural Transmission
• your religious beliefs, values, musical tastes etc are shaped by the culture in which
you are raised
• meme: a unit of knowledge transferred within a culture
• are analogous to genes, in that they are selectively passed from one
generation to the next though some, such as fads, die out quickly
unlike
natural
selection which typically occurs slowly over thousands of years,
•
meme can spread quickly - worldwide adoption of the internet
• although memes can be conditioned through association or reinforcement, many
memes are learned by watching others’ behaviour
• Cultural Beliefs About Learning
• children’s level of achievement can sometimes differ widely across cultures
• asian children perform better in school than north americans and europeans
• explanation of the learning gap
• different cultures have different understandings of learning that affect their
motivation to lean and learning behaviours
• asians view learning as more adaptive - we all learn if we work hard
• westerners see learning more as - some people can learn well and others can
not
Leaning Can Occur Through Observation
• observational learning: learning that occurs when behaviours are acquired or
modified following exposure to others performing the behaviour
• offspring can learn basic skills by watching adults perform those skills
• Bandura’s Observational
• Albert Bandura performed studies
• showed a film about an inflatable doll named bobo to preschoolers
• one film showed a person being aggressive with the doll, the other one being
gentle
• children that watched the violent one acted more aggressively after when
playing with their toys
• the result suggests that exposing children to media violence may encourage them
to act aggressively
• Social Learning of Fear
• Susan Mineka tests to see if monkeys raised in labs will be afraid of snakes (like
wild monkeys) by observing other monkeys behaviour
• humans can also learn to fear specific neighborhood stimuli by observing others even just by hearing that things are dangerous
• being afraid of a certain neighborhood after hearing that someone got raped
social
forces play an important role in the learning of fear
•
• Teaching Through Demonstration
• because humans can learn through observation, they can be taught many complex
skills through demonstration
• parents use slow and exaggerated motion to teach their children how to tie their
shoes
Animals and Humans Imitate Others
• human and non-human animals often imitate each other
• within a few days of being born, babies imitate facial expression
• modeling: the imitation of observed behaviour
• modeling is influenced by several factors: generally we imitate people that area
attractive, have high status, are somewhat similar to ourselves
• modeling will only be effective if the observer is physically capable of imitating the
behaviour
• watching tiger woods hit a 300 yard ball does not mean we can imitate it
• we imitate what we see in others, especially those we admire
• dress like celebrities
• Vicarious Reinforcement
• vicarious reinforcement: learning that occurs when people learn the
consequences of an action by observing others being rewarded or punished for
performing the action
• another factor that determines whether observers imitate the model is whether the
model is reinforced for performing the behaviour
• another test with the Bobo doll
• 3 groups of children, film ended in 3 different ways
1. no consequence for aggressive behaviour were rewarded for their
aggressive behaviour with candy - children more likely to be aggressive
2.
3. punished for bad behaviour by spanking and verbal - children less likely to
be aggressive
this
does
not mean that the less aggressive children did not learn the behaviour
•
• key distinction in learning is between the acquisition of a behaviour and its
performance - all the children learned the behaviour but only those who saw
the model being rewarded performed the behaviour
• Mirror Neurons
• mirror neurons: neurons that are activated during observation of others
performing action
• mirror neurons in monkeys become activated when watching another monkey do
something
• the same mirror neurons would be activated if the monkey actually performed the
task
• mirror neurons are especially likely to be activated if the monkey is watching a
monkey do a task with a particular goal
• similar mirror neurons exist in humans
• every time you observe another person engaging in an action, similar neural
circuits are firing both in your brain and in the other person’s
• since firing of mirror neurons does not always cause the observer to imitate some
theorists speculate that mirror neurons may help us predict other behaviour
• different speculations include:
• they are the neural basis for empathy (stepping into someone else’s shoes)
• important for the human’s ability to communicate
• Media and Violence
• a tv in the US is on for 5-6 hours / day
• people watch average of 3 hours of media / day
• sunday morning cartoons are watched by 60% of children - average of 20 violent
acts / hour
• it is difficult to prove (correlation does not prove causation) but children who play
violent video games / watch violent movies are more likely to be violent
What Is The Biological Basis of Learning? 268
• learning involves relatively permanent changes in the brain that result from
exposure to environmental events
• Dopamine Activity Underlies Reinforcement
• skinner and other defined reinforcement strictly in terms of whether it increase
behaviour
• they were not interested in why it increase behaviour
• generally, positive reinforcement works because it provides the subjective
experience of pleasure
• the neural basis of this reinforcement is the release of the neurotransmitter
dopamine
• dopamine is involved in motivation and emotion
• dopamine plays an important role in the experience of reward and is thus crucial
for positive reinforcement
• Pleasure Centers
• Olds and Milner experiment
• put rats in a cage with a lever to self-administer shock to a specific site in
their brains
• this procedure is also called intracranial self-stimulation (ICSS)
• rats would choose ICSS (electrical shock) over food, water, sex, and even
crossed painful electrified grids to receive it
• Olds and Milner referred to brain regions that support ICSS as pleasure centers
• ICSS acts on the same brain regions as those activated by natural reinforcers
(such as food, water, sex)
• both ICSS and natural reward appear to use the same neurotransmitter system
(namely dopamine)
• this evidence suggests that dopamine serves as the neurochemical basis of
positive reinforcement in operant conditioning
• Nucleus Accumbens Activation
• nucleus accumbens: is a subcortical brain region that is part of the limbic system
• experience of pleasure usually results from activation of dopamine neurons in the
nucleus accumbens
• enjoying food depends on dopamine activity
• food tastes better when you are hungry because more dopamine is released under
deprived that non-deprived conditions
•
•
•
•
in operant conditioning, dopamine release sets a reinforcer’s value
drugs that block dopamine’s effects disrupt operant conditioning
the blocker decreased the value of reinforcement
drugs that enhance dopamine activation (cocaine, amphetamines) increase
stimuli’s reward value
• Secondary Reinforcers Also Rely on Dopamine
• natural reinforcers appear to signal reward directly through the activation of
dopamine receptors in the nucleus accumbens
• through classical conditioning process, neutral stimuli that at first fail to stimulate a
dopamine release do so readily after being paired with unconditioned stimuli
• anticipation of money rewards (secondary) can activate dopamine systems
Habituation and Sensitization Are Simple Models of Learning
• learning involves relatively permanent changes in the brain that result from
exposure to environmental events
• Richard Semon - memories are stored through changes in the nervous system
• engram: storage of learned material
• Donald Hebb - learning results from alterations in synaptic connections
• one neuron excites another, some change takes place such as the synapse
between the two strengthens
• subsequently one neurons firing becomes increasingly likely to cause
other’s firing
• “cells that fire together, wire together”
• Eric Kandel
• used the aplysia (small marine snail with very few neurons) to study neural
basis of 2 types of simple learning:
• habituation: a decrease in behavioural response following repeated
exposure to nonthreatening stimuli
• orienting response: an an animal encounters a new stimulus, it
pays attention to it
• if stimulus is neither harmful nor rewarding (meaningless) animals
learn to ignore it
• sound of clock in the background
repeated
habituation trials can lead to a state of habituation that lasts
•
several weeks
• *a reduction in neurotransmitter release leads to habituation
• sensitization: an increase in behavioural response following exposure to a
threatening stimulus
• while studying you smell burning, you won’t habituate to the smell
• sensitization leads to heightened responsiveness to other stimuli
• Kandel’s research shows that alterations in the functioning of the synapse lead to
habituation and sensitization
Long-Term Potentiation Is A Candidate for the Neural Basis of Learning
• long term potentiation (LTP): the strengthening of a synaptic connection so that
postsynaptic neurons are more easily activated
• to demonstrate LTP, researchers first establish the extent to which electrically
stimulating one neuron leads to an action potential (level of stimulation needed to
activate or fire) in a second neuron
• LTP occurs when the intense electrical stimulus increases the likelihood that
stimulating one neuron leads to an action potential in the second neuron
• LTP results from changes in the postsynaptic neuron that make it more easily
activated
• numerous lines of evident support the idea that LTPT is the cellular basis for
learning and memory
• same drugs that improve memory also lead to increased LTP
• neurons that signal the unconditioned stimulus are active at the same time as
those that signal the conditioned stimulus
• over repeated trials, the synapses that connect these 2 evens becomes
strengthened so that when one fires, the other fires automatically, producing the
conditioned response
• NMDA receptor (a type of glutamate receptor) is required for LTP and has a
special quality: it opens only if a nearby neuron fires at the same time
• LPT and the NMDA Receptor