Learning and Behaviour

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Chapter 5

• Learning and Behaviour

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The Big Picture
This chapter focuses on the manner in which we
learn to behave in certain ways given certain
environmental conditions The emphasis will be
primarily on stimulus-response mappings, and how
they are formed There will be very little
discussion of cognitive states or processes
which contrasts quite strongly with the methods
that are more popular today
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The Starting Place - UCSs UCRs
We come equipped with many stimulus response
mappings that simply reflect our machinery in
action for examples gt When we put food in
our mouths, digestive processes are
initiated gt If a projectile is coming at our
face we close our eyes, duck our heads, raise
our hands, and sometimes hold our
breath These associations are the produce of
evolution (or creation) and the components of
them are labeled as unconditioned stimuli (UCS)
and unconditioned responses (UCR) gt Food (UCS)
-gt Digestive Process (UCR)
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Habituation - Weakening the SR Mapping
The occurrence of some novel stimulus in the
environment (UCS) tends to lead to a startle
response (UCR). However, if the stimulus occurs
repeatedly without any positive of negative
consequence, the startle response
stops occurring. This is a process called
habituation as examples of it consider (1)
Those weird house noises you no longer hear (2)
Airplanes at my old place Basically, if the UCR
proves itself unnecessary in the presence of some
UCS the UCR may occur less and less
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Classical Conditioning - The Extensionof SR
Mappings to New Stimuli
In 1904, a Russian scientist named Ivan
Pavlov stumbled across an interesting phenomenon
while studying how the canine digestive system
worked. This phenomenon has come to be called
classical conditioning, and it explains how new
stimuli can come to be associated with certain
behavioural responses. Pavlovs is now known as
one of the most influential figures in
psychology, and his experiments helped to start
the wave of behaviourism that ruled
psychology for many years.
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Pavlovs Experiment - Baseline
At the beginning of the experiment, if a bell was
rung near the dog it did not salivate.
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Pavlovs Experiment - Baseline
However, if food (UCS) was presented to the dog,
it would salivate (UCR)
UCS
UCR
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Pavlovs Experiment - Conditioning
Over a number of trials, the bell the CS or
conditioned stimulus is rung just before the
food is delivered
UCS
CS
UCR
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Pavlovs Experiment - Testing
After a number of conditioning trials, if the CS
is presented alone, it will typically lead to a
conditioned response which is similar in form,
if not degree, to the unconditioned stimulus
CS
CR
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Classical Conditioning Overview
In order for classical conditioning to be
effective, the UCS must reliably follow the
CS. If this association is not strong throughout
the conditioning phase, the learning will be
weak. If the association between the CS and UCS
is terminated after conditioning the CR will
eventually not occur in response to the CS - a
process called extinction. However, an extinct
CS-CR mapping can become active again quickly if
the CS/UCS association again becomes strong again
- a process called spontaneous recovery.
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Operant Conditioning
The term operant refers to the notion that
humans learn from operating on their environment.
We behave, then note the consequences and use
them to modulate future behaviour. The famous
cat torturer Edward Thorndike was one of
the first to study operant conditioning. Early
on, his research focused on learning by trial
and accidental success Through this, he formed
the Law of Effect which states that a behaviour
that is followed by a positive consequence
will tend to be repeated --- note similarity to
evolution theory.
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Behavior Analysis B. F. Skinner
Skinner strongly championed the experimental
study of the Law of Effect, and he made strong
claims to its application to human behaviour --
Walden Two He invented a number of devises for
studying operant conditioning the most famous
being the operant chamber or Skinner Box This
device allows the experimenter to control a
number of environmental stimuli, and allows him
to deliver both rewards (most typical) or
punishment.
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Basic Skinner Box
Lights
Speaker
Lever
Food Hopper (reward)
Floor the can be electrified (punishment)
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Measuring Behaviour
Behaviour is often measured in terms of rate of
responding (i.e., number of responses within some
period of time) Skinner came up with a response
recorder apparatus that allowed him to record
each response over time. This device is called a
cumulative recorder because it keeps track of
the total number of responses over time. Thus,
the effects of variables on the response rate
could be measured allowing one to see if certain
variables strengthen (i.e. increase) the response
of interest, or weaken (i.e., decrease) the
response of interest.
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Graph from a Cumulative Recorder
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Notion of a Three-Term Contingency
Skinner described any behavioural event in terms
of three parts (1) The preceding event, which
usual involves the presentation of a
discriminative stimulus (2) The behavioural
response to the discriminative
stimulus (3) The following event, which
represents the consequence of our
behaviour e.g., training killer whales at Sea
World
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Ways of Altering Behaviour
Positive Reinforcement - A given behaviour tends
to increase in frequency if it is followed by an
appetitive (desirable) stimulus. Negative
Reinforcement - A given behaviour also tends
to increase in frequency if it is reliably
followed by the termination of an aversive
(undesirable) stimulus. Punishment - A given
behaviour tends to decrease in frequency if it
is reliably followed by an aversive
stimulus Response Cost - A given behaviour tends
to decrease in frequency if it is reliably
followed by the termination of an aversive
stimulus Extinction - The reduction of a
behaviour if it is not reinforced
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Shaping Behaviours
Shaping - Teaching an organism to learn a new
behaviour through successive approximation. In
the case of a Dolphin learning a new trick, this
involves first rewarding behaviours that are very
generally consistent with the trick then
altering the criterion for reward, making it more
and more specific to the trick What about a prof
learning Karate, or someone learning a new
language?
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Intermittent Reinforcement
Refers to situations in which not every
occurrence of a response is reinforced. This
leads to an issue termed schedule of
reinforcement Fixed-ratio An animal can be
rewarded after making some set number of
responses - leads to behaviour bursts Variable-r
atio Same as above except it is delivered
on average every so many behaviours - leads to
rapid and constant responding (slot
machines) Fixed Interval Reinforcers can be
deliver after a set period of time has passed -
leads to responding just before Variable
Interval Same as above except random - leads
to slow, steady responding
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Resistance to Extinction
A behavior that has been learned on an
intermittent reinforcement schedule is much more
resistant to extinction that one that had been
rewarded more consistently The higher the ratio
of the reinforcement, the higher the
resistance What does all this suggest about
gambling?
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Generalization and Discrimination
In classical conditioning, generalization refers
to the extent to which a stimulus similar to the
CS can elicit the CR. In operant conditioning,
generalization refers to the extent to which a
stimulus similar to the discriminative
stimulus elicits a response. Animals can learn
to both generalize, and simultaneously, to
discriminate. In a sense, they learn to
categorize stimuli into those that should be
responded to, and those that are not worth the
effort. gt Pigeon learning human concept gt Why
are weddings so stressful!
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The Importance of Secondary Reinforcers
Most operant conditioning experiments use
primary reinforcers during learning (e.g. food,
pain). However, much of our learning in the real
world is more affected by secondary reinforcers
(e.g., money, smiles, pats on the back,
compliments). These secondary reinforcers gained
their importance via good old classical
conditioning being predictive of UCSs that are
associated with primary reinforcers
(UCRs). Without secondary reinforcers we would
be focused only on short-term responding, and
would not learn very complex sets of behaviours
sociopaths?
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Conditioning Complex Behaviours
Our society contains many means to shape
behaviour via aversive reinforcers (e.g., fines,
jails). Punishment is an effective means
of changing behaviour and it often leads to
fairly immediate results which reinforces the
punisher of course. Society cannot always
control the positive reinforcers present in some
situation, but it can control the negative.
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Current Research with Humans
Rules Reinforcers Human behaviour is often an
interaction between reinforcers and rules. Rules
are descriptions (often inaccurate) of behaviours
that will rewarded or punished in various
ways Often people will obey the rules
(instructions) originally, but then modify their
behaviour in accordance with the reinforcers. gt
text book example gt rolling stop example
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Current Research with Humans
Drug Use and Abuse Behavioural
Psychopharmocology is the study of how
drugs influence behaviour. In this area,
Skinners 3 term contingency translates
into (1) drugs, (2) their effects on behaviour,
and (3) their reinforcing effects As it turns
out, most psychoactive drugs act as strong
reinforcers in both humans and animals Most
preferred drugs correlate with those most
abused by humans - Monkey coke-heads
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An Few Final Thoughts
Note once again the lack of attention to
thought in all of this In response to attempts
at artificial intelligence, Skinner responded,
The important question is not whether
machines can be made to think, it is whether
humans think Consider this in light of the
Conditioning to Kill situation and its possible
links to post-traumatic stress disorder. Think
also of the quote from How the Mind Works
Chapter 5 - Learning and Behaviour