Transcript Slide 1

Learning theory
Classical conditioning, operant conditioning
and social learning theory
25th September 2012
Dr Susannah Redhead
Clinical Psychologist
North Cambridge Intake and Treatment Team, CPFT
[email protected]
Objectives
1. To provide an introduction to the main concepts and terminology relating
to classical conditioning, operant conditioning and social learning theory
2. To evaluate these approaches with regard to their implications for our
understanding and treatment of mental health difficulties.
3. To enable you to do well in your MCQs!
Plan
Classical conditioning
- Describe and evaluate
Operant conditioning
- Describe and evaluate
Social learning theory
- Describe and evaluate
With an
emphasis on
clinical
implications
Learning is...
• ...”the process by which relatively permanent
changes occur in behavioural potential as a result of
experience” (Anderson, 1995).
• What kinds of changes?
- Overt, behavioural changes?
- Covert, cognitive changes?
Classical
conditioning
Or....
Pavlovian
conditioning
Ivan Pavlov (1849-1936)
A Russian physiologist
Before working on classical conditioning,
he already had won a Nobel prize for his
work on digestion.
Primarily worked with dogs.
Developed a surgical technique for
developing a dogs salivatory secretions
which incorporated a tube attached to the
side of its cheek so the drops of saliva
could be easily measured.
What Pavlov (1927) noticed...
- The dogs would start salivating before the food was given to
them, on the basis of visual stimuli (seeing the feeding
bucket) and auditory prompts (hearing the footsteps of the
laboratory assistant approaching) – “psychic secretions”
- Pavlov resolved to explain this phenomenon.
Classical conditioning
Higher order conditioning – a cynical
example
UCS – Dessert/ pressies
UCR - Pleasure
NS/ CS - Grandma
CR - Pleasure
NS/ CS – Grandma’s
perfume
CR - Pleasure
Some more concepts from classical
conditioning...
• Generalisation – A CR can be elicited to stimuli that are
similar but not identical to the original UCS...however the
strength of the CR is different (e.g. For Pavlov, less saliva).
• Discrimination – The strength of the CR to one CS is
strengthened at the same time as a second CS is weakened –
i.e. Learning to respond differently to slightly different stimuli
Some more concepts from classical
conditioning...
• Experimental extinction – The repeated presentation of the
CS in the absence of the UCS removes the conditioned
response
• Spontaneous recovery – The re-emergence of responses over
time following experimental extinction e.g. Dogs brought back
into the experimental situation after extinction has occurred
demonstrate some salivation in response to the tone.
Four types of classical conditioning...
1. Delayed or forward
The CS is presented before the UCS an remains present while the
UCS is presented and until the UCR appears. Conditioning
has occured when the the CR appears before the UCS is
presented. A half-second interval produces the strongest
learning. As the interval increases, learning becomes poorer.
2. Backward
The CS is presented after the UCS. Produces very little, if any
learning in laboratory animals. However, much advertising
uses backwards conditioning.
Four types of classical conditioning...
3. Simultaneous – The CS and UCS are presented together. This
often occurs in real life situations (e.g. The sound of the
dentists drill accompanies the contact of the drill with your
tooth).
4. Trace – The CS is presented and removed befoe the UCS is
presented, so only a memory trace of the the CS remains to
be conditioned. The CR is usually weaker then in delayed or
simultaneous conditioning.
Classical conditioning – Little-known
facts...
• A wide variety of stimuli were recorded in Pavlov’s writings,
including electric shocks, whistles, metronomes, tuning forks, and a
range of visual stimuli.
• Pavlov's experiments extended to children, some of whom
apparently underwent surgical procedures, similar to those
performed on the dogs, for the collection of saliva.
• CR does not necessarily equal the UCR – Pavlov found the content
of the dogs saliva was different
• Classical conditioning is a widely recognised process accross
organisms. Occurs in dogs, rats, the human foetus, neurons
Evaluation of classical conditioning
1.
Clinical relevance and utility
- Explanation of development of
specific phobias, trigger generalisation in PTSD
- Implications for intervention: Implosion therapy, flooding ,
Systematic desensitisation, aversion therapy, exposure and
response prevention for OCD, prolonged exposure therapy
for PTSD
Critiques...
2. Assumes passivity, irrelevance of cognition
3. Ethics?! Ecological validity.
4. One trial learning – Garcia, Ervin and Koelling (1966)
5. Natural associations
6. The role of language
Explanation of development of specific
phobias
The Little Albert example – Watson (1920)
Fear of white rat and other stimuli conditioned in 9m old child
UCS – Clanging metal bars (!)
CS – White rat
UCR – Fear
CR – Fear
Generalisation of fear response to fluffy white beards (or higher order
conditioning?)
Similar process in PTSD – conditioned responses, generalisation
Implosion therapy and flooding
Premise – if the stimulus evoking a fear response is presented without the
aversive experience that accompanies it, the fear response will be lost
• Implosion therapy
- The therapist exposes the client to vivid mental images of the feared
stimulus.
- Stimulus augmentation – the therapist encourages the client to consider the
most extreme form of contact with the feared stimulus
- After repeated trials, the stimulus loses its anxiety-provoking power
(“implodes” – extinction takes place)
• Flooding
- The individual is forced to confront the object or situation evoking the fear
response in vivo, e.g. Wolpe (1973) – adolescent girl forced into the back
of a car...!
* For many people, these procedures would be too traumatic*
Systematic desensitisation and aversion therapy
Systematic desensitisation
- Relaxation training then gradual exposure to anxiety
hierarchy
- Based on the concept of reciprocal inhibition – fear and
anxiety are mutually exclusive
Aversion therapy
- Pairing an unpleasant stimulus with a desired
but socially undesirable behaviour
- E.g. Treatment of alcohol abuse –
alcohol paired with vomit-inducing substance
- A Clockwork Orange
More recent developments in interventions
based on classical conditioning
Exposure and response prevention for OCD
- Less emphasis on relaxation as an alternative response then SD, as this can
be undertaken in a ritualistic manner
- Purpose – gradual reduction in anxiety response, alleviating need to rely
on compulsions
•
-
Prolonged exposure therapy (Foa, 2007)
Exposure to traumatic memories in PTSD.
Imagined then audio-recorded.
Played and replayed until anxiety
level subsides. Monitoring essential
(role of cognition?)
Critiques of classical conditioning
•
•
•
•
Assumes the passivity of the learner.
The cognitive aspect of learning is not incorporated into the
model
The role of language in learning is not taken into account – e.g.
Just telling a person the UCS will not be repeated again can cause
extinction (Davey, 1983)
Assumes repeated exposure necessary to explore learning.
However...
-One trial learning – Garcia et al. (1966), rats
rapidly conditioned to avoid sweet tasting
emetic substance
•
Natural associations – CC does not explain how some associations
are more easily made than others
• Operant conditioning
Or....
Instrumental conditioning
Classical vs. Operant conditioning
Premise of operant conditioning: Much behaviour is controlled
by its consequences (future stimuli), by events that precede it
such as in classical conditioning.
Operant conditioning:
Behaviour
Classical conditioning:
UCS
Unconditioned
behaviour
CS
Conditioned behaviour
Consequences –
reinforcement/
punishment
Thorndike’s law of effect (1898)
•Cats had to learn to operate a latch to
retrieve a piece of fish
•Each time they were returned to the
puzzle box, it took less time to escape
•Trial and error learning
•What was being learnt –a connection
between the stimulus (manipulative
contents of box) and the response
(behaviour allowing cat to escape)
Thorndike’s “puzzle box”
The stimulus-response connection is
“stamped in when pleasure results from
the act and stamped out when it
doesn’t”
B. F. Skinner (1904-1990)
BF – Burrhus Frederic
Founder of radical behaviourism
Inventor of numerous creations
including the controversial “air
crib”, cumulative recorder, operant
conditional chamber, teaching
machine and pigeon-guided
missile.
Skinner’s “analysis of behaviour”
(1904)
Skinner developed his own version of
Thorndike’s “puzzle-box”
The animal presses the lever (in the case of
rats) or pecks an illuminated disk (for
pigeons)
The experimenter decides what the
relationship will be between the pressing/
pecking, and the subsequent
consequences.
The experimenter has complete control
over the animal’s environment
What Skinner found...
The “law of reinforcement” – a response is more likely to be repeated if it is
followed by a reward or “positive reinforcer”
The rats soon learnt the lever could result in food pellets being released
(continual reinforcement), so pressed the lever more and more often.
The effects of a positive reinforcer are greater if it follows immediately after
the behaviour.
The probability of a response decreases if not followed by the positive reinforcer (experimental extinction). There is usually some spontaneous
recovery after extinction has occurred.
Skinner (1938) identified several different schedules of reinforcement apart
from continual reinforcement – collectively referred to as partial
reinforcement schedules. Please refer to Appendix A for more detail
Primary and secondary reinforcers
Primary and secondary reinforces are the two main type of reinforcers in
operant conditioning.
Primary reinforcers are stimuli that are needed to live e.g. Food, water, sleep,
air.
Secondary reinforcers are reinforcing because we have learnt to associate
them with primary reinforcers, e.g. Money, praise, attention.
Some more concepts from operant
conditioning...
• How do we condition an animal to produce a response it would not
produce naturally?
By shaping – in which the animal moves towards the right behaviour with
successive approximations
E.g. if we happened to want to train pigeons to play table tennis...
• Latent learning - It is possible for learning to occur without any obvious
impact on performance...until positive reinforcement is provided
The rats in mazes example
Negative reinforcement and
punishment
Lever
pressing
Lever
pressing
Lever
pressing
Positive
reinforcement
Negative
reinforcement
Food is presented
Electric shock is
switched off (escape
learning)
OR
Avoided altogether
(avoidance learning)
Punishment
Electric shock is
switched on
Negative reinforcement and
punishment
Negative reinforcement
The removal or avoidance of a negative stimuli
Escape learning: Learning that occurs in order to cause a negative
stimulus to cease
Avoidance learning: Avoidance of the negative stimulus altogether
e.g. Stopping at traffic lights to avoid an accident.
The shuttle box example – electric shocks can be delivered to one
compartment of the shuttle box independently of the other.
Warning signal – pigeon jumps to the other compartment.
Punishment
The probability of a response being made is reduced by following it
(quickly) with an aversive stimulus e.g. Telling off.
Learned helplessness
Seligman (1975)
-
-
Dogs exposed to aversive stimuli they couldn’t avoid, in the form of electric shocks
Afterwards, put in a shuttle box; they could escape by jumping over to the other
side.
In fact, most of the dogs passively accepted the shocks.
The term learned helplessness is now used to refer to passive behaviour in
situations when appropriate action could be taken, e.g. Depression, domestic
violence situations.
Classical vs. Operant conditioning
Similarities
Both types of associative learning
Both involve generalisation, discrimination, extinction and spontaneous
recovery
In practice, it can be hard to tell them apart
Differences
CC – Behaviour involuntary, OC – voluntary
CC – Process works the same regardless of whether stimulus is pleasurable or
aversive. OC – likelihood of response depends on the extent to which it’s
pleasurable.
CC – new stimulus response connections are formed. OC – more concerned
with the strengthening or weakening of behavioural tendencies already
exhibited by the animal.
Classical vs. Operant conditioning
Differences cont.
CC – reinforce presented irrespective of what the animal does, before the
response. OC – reinforcer presented only if the animal behaves in a certain
way, after the behaviour
CC – strength of conditioning measured in terms of response magnitude and
or latency. In operant conditioning – response strength is measured as
response rate.
Evaluation of operant conditioning
1. Clinical relevance and utility
- Explanation of development of depression
and the maintenance of phobias.
- Implications for intervention – Therapies
based on extinction, therapies based on
punishment, Token economies, Applied
behavioural analysis (ABA), behavioural
activation/ activity scheduling
Critiques...
2. Other critiques relevant to classical conditioning are also relevant here
(and these are also relevant to classical conditioning).
3. Does not take account of insight learning (the aha moment) or
observational learning
4. Equipotentiality
An explanation of the development of
depression
- Lewisohn (1974) – Life events involving loss induce depression due to
reduced opportunities for positive reinforcement, which in turn leads to
increased withdrawal.
-
Lewisohn suggests that social withdrawal leads to concern and attention,
which can reinforce the depressed behaviour. When the concern wanes,
the depression is exacerbated.
-
Depression is associated with a reduction in pleasant activities/
opportunities for positive reinforcement (pleasure/ mastery – Padesky).
An explanation of the maintenance of phobias
Mowrer’s (1947) two-factor theory
- Phobias are acquired through classical conditioning (factor 1) and
maintained through operant conditioning (factor 2), as the
avoidance of phobic stimulus/ reduction in anxiety is negatively
reinforcing.
- Rachman (1984) sees avoidance as being maintained by positive
feelings of safety.
- Rosenhan and Seligman (1984) – Prepared conditioning – we are
genetically predisposed to acquire phobias towards certain stimuli,
e.g. Snakes rather than flowers.
Interventions based on extinction/
punishment/ token economies
Premise – If a difficulty has been acquired through operant
conditioning, it can be eliminated through it.
• Interventions based on extinction
- Identify then eliminate the reinforcer e.g. Attention...but ensure the
underlying need is met through another source.
• Interventions based on punishment
- E.g. In a secure hospital – time in solitary.
- Not common as not effective as strategies using positive
reinforcement for bringing about behaviour change.
• Token economies
Tokens are provided to exchange for priviledges, in order to encourage
desirable behaviour
? Institutionalisation
ABA/ behavioural activation
• Applied behavioural analysis (ABA)
Primarily used with people with
autism, and those with a learning
disability/ challenging behaviour.
Functional analysis involving ABC
monitoring
Interventions – e.g. shaping, teaching
communication skills, identifying other
outlets for functions served by the
behaviour…
•Behavioural activation/ activity scheduling
Goal setting around increasing levels of activity to ensure increased pleasure
and mastery (positive reinforcement). Activities rank-ordered by difficulty.
Critiques of operant conditioning
3. Does not take account of insight learning (the “aha” moment) or observational
learning
Several types of learning do not appear to depend on conditioning principles.
Kohler (1925) – Insight learning – chimps suddenly able to reach the banana.
Observational learning…see next slide!
4.
Equipotentiality
Skinner seems to have believed that any response could be conditioned in any
stimulus situation
Not the case, due to “instinctive drift” –
pigs push a coin around in the mud
rather than drop it in a piggy bank
Social learning
theory
Or….
Observational
learning
Albert Bandura, born 1925
Key proponent of social learning theory
Based on studies of children, in particular the
observation that children tend to imitate their
parents
People learn by observing the behaviour of
others and the outcome of those behaviours,
which does not necessarily involve direct
exposure to reinforcement
The expectation of reinforcement influences
cognitive processes that promote learning.
Therefore attention and memory play a
critical role in learning.
Particularly influential in the understanding of
aggressive behaviour
Bandura et al.’s Bobo doll studies (1963, 1965)
1963 -Children were allocated to one
of two groups, either watching an
aggressive film or a non-aggressive
film featuring an adult interacting with
a Bobo doll.
The children were left to play with the
Bobo doll…
Guess what happened next?
1965 – Three groups – 1. violence, 2.
violence with reward, 3. violence with
punishment
Children in the punishment group
demonstrated equal learning, but
least likely to apply this to their
bahviour.
Bandura’s (1974) five conditions
1. Attention: the person must first pay attention to the model.
2. A visual image or semantic code for the modelled behaviour is stored in
the memory.
3. Retention: the observer must be able to remember the behavior that has
been observed, e.g. through rehearsal.
4. Motor reproduction: the third condition is the ability to replicate the
behavior that the model has just demonstrated.
5. Motivation: the final necessary ingredient for modeling to occur is
motivation, learners must want to demonstrate what they have learned,
e.g. due to the anticipation of positive reinforcement.
Evaluation of social learning theory
• Influential in explaining aggressive behaviour
e.g. children who watch violent TV programs are more likely to behave in
an aggressive way
(is watching violent TV a correlation of lack of boundaries/ discipline…?)
• The majority of forensic psychologists would maintain that people’s
internal emotional state, interpretation of the current situation and
personality amongst other things are also important factors
• HCR-20 – exposure to violence is not a predictor of violence (although this
would be hard to quantify)
• Ethics/ ecological validity yet again – would the children have attacked
another child?
To finish…
• Have we met our objectives?
• Any questions?
Good luck with the rest of your training!