Download Classical Conditioning

Psych 120
General Psychology
Christopher Gade
Office: 1030A
Office hours: MW 4:30-5:30
Email: [email protected]
Class MW 1:30-4:30 Room 2240
What’s on tap?
Today we’re going to discuss behaviorism
and how it relates to learning.
We’ll do this by…
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Briefly reviewing the field of behaviorism and
discussing one of its most influential characters.
Going over one of the most popular behavioral
discoveries of all time.
Discussing classical conditioning and the basics
of how this learning process works.
Learning:
A relatively permanent change in an
organism’s behavior due to experience.
Behaviorism: the approach to
Psychology that involves
observable cause-and-effect
relationships between conditions
and behavior.
• Origins in ‘stimulus-response’
psychology.
• Takes into account an organism’s
history of experiences, i.e.
knowledge.
• Aims to decode the ‘basic laws of
behavior’.
• Assumes a deterministic perspective
and emphasizes the influence of the
environment.
John B Watson
Pioneer in the field of behaviorism
Considered by many to be the founding
father of behaviorism. This might not be
the case, but he was definitely their poster boy.
Famously known for his statement:
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“Give me a dozen healthy infants, well-formed, and my own
specified world to bring them up in and I’ll guarantee to take any
one at random and train him to become any type of specialist I
might select…”
Most famous experiment was with Baby Albert.
Ivan Pavlov (1839-1946)
• Originally interested in
the digestive system of
dogs.
• From his research, he
discovered ‘psychic
salivations’ that dogs
would show (for which he was awarded a Nobel
prize)
• Realized that this form of learning was interesting
and dedicated his time to studying how dogs
developed this behavior
•
5:28
Classical Conditioning
In this form of learning, the
learned responses develop from
an initial pairing of two pieces
of information:
•
The unconditioned stimulus
(US): a stimulus that elicits an
unlearned, or reflexive response.
•
The unconditioned response
(UR): a response to a stimulus
that is automatic.
Classical Conditioning
After the initial pairing of
information, a “neutral
stimulus” (NS) is presented to
the individual.
A “training” or “pairing”
procedure then begins until the
neutral stimulus is recognized
to be associated with the
unconditioned stimulus:
This pairing of stimuli
eventually leads to a
“conditioned response” (CR)
to the newly “conditioned
stimulus” (CS).
Classical Conditioning
Important concepts
•
A learning curve tells us whether conditioning is occurring,
that is, whether, when and how strongly the CS is eliciting the
CR over time.
•
Second-order conditioning is a process of adding new CSs to
the conditioned CSs (sequentially).
•
If, after the conditioning, the CS is presented without the US
repeatedly, the association will deteriorate and the CS will
cease to elicit the CR – this is called extinction.
– however, extinguished associations can be reconditioned
(usually faster than the initial conditioning) AND,
sometimes organisms show spontaneous recovery of
extinguished behaviors.
Extinction and Spontaneous Recovery
Strength
of CR
Acquisition
(CS+US)
Extinction
(CS alone)
Spontaneous
recovery of
CR
Extinction
(CS alone)
Pause
What influences the strength of a learned response
through classical conditioning?
Conditioning occurs more rapidly when the
neutral stimulus is relatively unfamiliar.
The less time that elapses between the
presentation of the CS and the UCS, the faster
the CR is acquired.
The CR will be acquired more quickly when the
CS precedes the UCS (forward conditioning).
Specific connections between CS’s and UCS’s
are stronger in different species.
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Rat and Poison example
What about stimuli that are similar to the neutral
stimulus?
•
Sometimes, organisms respond to new, irrelevant stimuli that
closely resemble the original Neutral stimulus with the same
CR, this is called generalization.
• Organisms can also learn
through conditioning to
discriminate between
similar stimuli, if a CS–
is introduced into the
conditioning process.
What does this tell us about learning?
It tells us how we can learn about how our minds
might pair stimuli with each other.
However, it doesn’t inform us about how we
know about what to do and not to do in our
world.
Next, we’ll revisit the world of behaviorism from
a different perspective; from the world of operant
conditioning.
Edward Thorndike (1874-1949)
•
Originated the idea of instrumental learning.
•
Studied cats and other animals learning by trial and error to
escape from puzzle boxes.
The Thorndike Laws
Law of Effect: Behaviors followed by
favorable consequences become more
likely; behaviors followed by unfavorable consequences
become less likely.
Law of Readiness: A series of responses can be chained
together if they belong to the same action sequence and will
result in annoyance if blocked.
Law of Exercise: Connections become strengthened with
practice and weakened when practice is discontinued.
B. F. Skinner (1904-1990)
Skinner attempted to expand on
Thorndike’s original theories of
instrumental learning. He proposed
that the learning process has a very predictable
response to rewards and punishments. His work
set out to show how those responses to behavior
influenced future behaviors (e.g. operant
conditioning).
The majority of Skinner’s work was done on rats
and pigeons in elaborate boxes that he designed.
These boxes were called “Skinner Boxes”.
15:30
Operant Conditioning
•
The process of learning to associate a behavior with a
consequence, in order to behave in a manner that maximizes
reinforcing and minimizes punishing events.
– Reinforcement: any event that increases the future
probability of the most recent behavior.
– Punishment: any event that decreases the frequency of the
preceding behavior
– What makes something reinforcing or punishing?
– Biologically useful
– Intrinsically satisfying
– Restores equilibrium
* Disequilibrium principle: any behavior that leads to a return to
equilibrium will be reinforcing.
But there’s more…
Not only are there reinforcements and punishments in operant
conditioning, but these responses are either positive (adding
something), or negative (taking something away).
The 2x2 Matrix of Operant Conditioning:
•
•
•
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Positive reinforcement: an introduction of a pleasurable stimulus, which
will increase the likelihood of the future occurrence of the behavior (e.g.
chocolate cake).
Negative reinforcement: a removal of an aversive stimulus, which will
increase the likelihood of the future occurrence of the behavior (e.g.
nagging).
Positive punishment: an introduction of an aversive stimulus, which will
decrease the likelihood of the future occurrence of the behavior (e.g.
spanking).
Negative punishment: a removal of a pleasurable stimulus, which will
decrease the likelihood of the future occurrence of a behavior (e.g.
taking away your allowance).
What type of reinforcement is this?
What about this one?
A final review of the 2x2 matrix…
Different Schedules of Reinforcement/Punishment
•
Continuous reinforcement: reinforcement for every correct response.
•
Partial/intermittent reinforcement: occasional reinforcement for a
correct response.
a.
Fixed ratio: Reward for a behavior after “X” responses. Causes faster
responders to get more rewards. Produces high rates of responding, but
quick extinction when the reinforcement is removed.
b.
Variable ratio: Reward for a behavior after a variable and unpredictable
numbers of responses. Gambling is a great example of this reward
system. It is very hard to extinguish after the connection is made.
c.
Fixed interval: Reward for a behavior after “X” amount of time has
passed. The responses are rather sparse in down time, but get more
vigorous right before time X.
d.
Variable interval: Reward for a behavior after a variable and
unpredictable amount of time. This causes slow, steady responding.
Responses x Time Diagram
Number of
responses
1000
Fixed Ratio
Variable Ratio
Fixed Interval
750
Rapid responding
near time for
reinforcement
500
Variable Interval
250
Steady responding
0
10
20
30
40
50
Time (minutes)
60
70
80
Effectiveness of Reinforcement
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All things being equal, most people learn fastest with
immediate reinforcement or immediate punishment.
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Punishment tends to be ineffective except for
temporarily suppressing undesirable behavior.
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Mild, logical and consistent punishment can be
informative and helpful.
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Though vicarious reinforcement can be effective,
vicarious punishment is often not.
So What Did We Learn?
We learned about operant conditioning.
We learned about Edward Thorndike and BF
Skinner.
We learned about how different reward
schedules can influence the rate, timing, and
extinction of learned responses.
We learned about learning.
And now…
After learning about how we take in information,
we’re going to examine how we keep that
information in our head.
Namely, this next series of topics is going to
discuss memory, and the way the mind stores
information.
What’s on tap?
In today’s last section, we’re going to
discuss the topic of memory. In this
lecture we’ll be addressing…
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The pioneer in research done on memory.
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Different tests of memory.
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Different memory time frames.
Hermann Ebbinghaus (1850-1909)
Sought to examine the
concept of memory from a
purely scientific viewpoint.
Had only one subject in
almost all of his studies on
memory… himself.
In these studies, he used
lists of nonsense syllables
in his attempts to examine
how our memories work.
Ebbinghaus (cont.)
His research was based on discovering how fast a
“normal” individual can learn, and forget information.
From this, he was able to generate both
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Learning curves
Forgetting curves
Ebbinghaus conducted experiments that varied in the
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# of syllables in the list
length of time before checking his memory after “learning” the
syllables
length of time before checking his memory after reading the
syllables
This variation in timing and the fact that he measure
memory after both introduction and memorization of
information provided us with a great starting block when
it came to examining memory
One of Ebbinghaus’
Remembering Curves
One of Ebbinghaus’
Forgetting Curves
Another One of Ebbinghaus’
Forgetting Curve
Let’s attempt a replication of one of
Ebbinghaus’ experiment...
Listen to the list of nonsense syllables that
are about to be read to you. Do not write
them down until you are instructed to do
so.
So what? What does that mean?
Ebbinghaus’ work led us to conclusions about how
the mind functions when storing meaningless
information that we are asked to recall. It also led
other researchers to begin exploring memory in a
more systematic way.
However, his work didn’t tell us about…
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our memories for meaningful information.
the different types of memory that we have.
our ability to remember information when we are asked
to reproduce it in a different manner.
how our reproduction of information might be altered.
Different Types of Memory Tests
Free Recall
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Ebbinghaus’ work
Cued Recall
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Famous authors
Recognition
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Name the dwarfs
Savings
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Name the capitols
Implicit Memory Performance
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Impaired memory example
Cued
Recall
Example
Cued
Recall
Example
Recognition Task
Grouchy
Gabby
Fearful
Sleepy
Smiley
Jumpy
Hopeful
Shy
Droopy
Dopey
Sniffy
Wishful
Puffy
Dumpy
Sneezy
Lazy
Pop
Grumpy
Bashful
Cheerful
Teach
Shorty
Nifty
Happy
Wheezy
Doc
Stubby
Different types of memory
categorized by length of storage
(temporal)
Sensory input
Attention to important
or novel information
Encoding
External
events
Sensory
memory
Short-term
memory
Encoding
Long-term
memory
Retrieving
Sensory Memory
First temporal category of memory
Capacity is thought to be infinite (or at least really large)
Attention to this information lasts only a fraction of a
second
After this fraction of a second, your brain breaks down
the information and attends to / remembers only the
information deemed relevant
Involves not only vision, but all of our senses
Is unfiltered by any portion of our brain
Lets test whether or not sensory
memory exists…
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Sperling’s Sensory Memory
Experiment
Short-Term Memory
(aka Working Memory)
Said to have a capacity of 7 + or – 2 items.
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Nonsense syllables example
Contains information from our sensory store that our
brain has deemed relevant (at least for the time being).
Information can be stored in this stage of memory from
anywhere between 10 seconds to a few days (some
scientists even argue that this can last up to 6 years).
After that, the memories stored are either forgotten
(information not regarded as important), or placed in our
long-term memory store.
Long-Term Memory
A collection of information that we value, have time
to remember, and feel like it will be of use in the
future.
Information in this part of our memory is often very
complex, but also subject to distortions or complete
fabrications.
There is debate as to whether or not we actually
ever forget information once it’s stored on long term
memory.
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Permanent storage that sometimes needs cues to recall
information.
Mixture of memories that are sometimes forgotten or
changed. This change/forgetting can be due to
Decay of neural connections
Rewriting of neural connections (computer example)
The Differences Between Our
Memory Systems
The Long-Term Memory Hierarchy
memories
Explicit
(declarative)
With conscious
recall
Facts-general
knowledge
(“semantic
memory”)
Personally
experienced
events
(“episodic
memory”)
Implicit
(nondeclarative)
Without conscious
recall
Skills-motor
and cognitive
Dispositionsclassical and
operant
conditioning
effects