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Learning
Learning is a change in behavior as a result of past
experience
Even though our principal interest is in how humans
learn, you’ll notice that a great deal of learning research
is conducted using animal subjects instead
Electrical Activity of the Neuron
• Less Complexity
•Greater Control Over Variables
•Generality of Principles
Classical Conditioning (Pavlovian Conditioning)
Ivan Pavlov (1849 – 1936) Famous
Russian Physiologist who won a Nobel
Prize in 1904 for his work on the
biochemical analysis of digestive
secretions of the stomach
Electrical
of the Neuron
HisActivity
later notoriety
stems from the
widely-known studies he performed on
conditioning of the salivary response
But his actual discovery of conditioned
reflexes occurred in a different context
much earlier
Classical Conditioning (Pavlovian Conditioning)
Procedure :
1. Dog transported from colony room to test cubicle and
chained to a hitch post
2. Food was prepared on a table 10’ away from subject
3. Dog was fed and 10 minute waiting period allowed
Electrical Activity of the Neuron
4. Fistula clamp was opened to allow for collection of
digestive secretions which occurred in response to
the arrival of food in the stomach
A mistake in the procedure leads to a discovery!
The fistula clamp was not closed properly allowing
for leakage. Secretions were observed taking place
prior to feeding. Pavlov termed these “Psychic
Secretions”
Classical Conditioning (Pavlovian Conditioning)
Electrical Activity of the Neuron
To more conveniently study “psychic secretions”, a new
procedure was devised involving the salivary reflex
The Classical Conditioning Paradigm
Stage 1 (Before Conditioning)
UCS
UCR
(Food)
(Salivation)
US (UCS) - Unconditioned Stimulus
A stimulus which reliably and without an prior
experience reflexively causes a response to occur
(the Unconditioned Response – UCR or UR)
Some of the Most Frequently Studied Classically
Conditioned Responses
Autonomic Activity
dry food or acid in mouth
salivation
electric shock
electrodermal activity (GSR)
electric shock or loud noise
cardiac acceleration
electric shock or loud noise
sudden respiratory inspiration
change in illumination
electric shock
pupillary reflex
food in viscera
gastro-intestinal secretion
insulin injection
hypoglycemia
Some of the Most Frequently Studied Classically
Conditioned Responses
Skeletal Activity
nipple on cheek or lips
rooting, sucking
loud noise
airpuff to cornea
suborbital
electric shock
blow to the eye
eyeblink or nictitating
membrane response
food in the mouth
mastication
electric shock
heat
pin prick
flexion, limb withdrawal
Some of the Most Frequently Studied Classically
Conditioned Responses
Skeletal Activity
nipple on cheek or lips
rooting, sucking
loud noise
airpuff to cornea
suborbital
electric shock
blow to the eye
eyeblink or nictitating
membrane response
food in the mouth
mastication
electric shock
heat
pin prick
flexion, limb withdrawal
Brain Activity
illumination
EEG occipital alpha rhythm
The Classical Conditioning Paradigm
Stage 1 (Before Conditioning)
UCS
UCR
(Food)
(Salivation)
CS
(Bell)
A neutral stimulus – that is, one that does not initially
cause the UCR to occur. This stimulus might be
referred to as the to-be-conditioned stimulus (CS)
The Classical Conditioning Paradigm
Stage 2 (During Conditioning)
CS
UCS
UCR
(Bell)
(Food)
(Salivation)
During conditioning we repeatedly pair, close together
in time, the originally neutral stimulus with the UCS
Temporal Contiguity is the key facet of combining
the stimuli for conditioning to in fact occur
The Classical Conditioning Paradigm
Stage 3 (After Conditioning)
CS
(Bell)
CR
(Food) (Salivation)
After conditioning we present the originally neutral stimulus
by itself and observe a conditioned response (CR)
We refer to the process that has occurred as “Acquisition”
since a new response is being acquired to the originally
neutral stimulus
The CR and the UCR are not identical responses. The CR
is always a fractional component of the UCR.
The Fractional Anticipatory Nature of Classical Conditioning
Classical Conditioning represents a learned connection
between environmental events that are likely to happen
together.
We become more effective in our response to events if
we prepare for them before they occur.
A dog can more efficiently eat and swallow food if he
salivates in anticipation of feeding.
Example of driving away in your car after class is over.
Preparing your keys in advance is anticipatory of a
situation that you are soon to encounter. The response
is fractional as you can not insert and turn the key until
the lock is encountered.
Organisms that prepare for events before they occur are
likely to be more effective in their response.
Stages of Learning
Stimulus Generalization
Stimulus Generalization Decrement
The degree of response to test
stimulus is gradually reduced as
stimulus differs more and more from
the original
Discrimination
Discrimination is said to occur when the subject responds
differently in the presence of one stimulus versus another.
Conditioned Emotional Response
Originally neutral stimuli can take on aversive characteristics as a result of being paired
with primary aversive stimuli. Watson and Raynor (1920) explored the development of a
conditioned emotional response in the infant “Little Albert”
Instrumental Conditioning
This form of learning is called “Instrumental” because the
subject desires his environment to change in some way. But
in order for this to occur, his own behavior will be
instrumental in bringing about the desired change.
For example, I’d like my environment to include a hot
steaming pizza in front of me right now.
But for this to become true, I must act in a certain way. My
behavior will be instrumental in causing this to occur.
An alternate terminology for this for of learning is to call it
“Operant Conditioning” because the behavior operates
upon the environment, changing it in some way.
Instrumental Conditioning Distinguished From
Classical Conditioning
Classical conditioning involves an association between
stimuli. The subject comes to learn that one stimulus is
contingent (dependent) upon the occurrence of another.
E.G., Pavlov’s Dogs learned that food delivery was
contingent upon the ringing of the bell
Instrumental conditioning involves an association
between a response and a stimulus. The subject comes to
learn that a stimulus is contingent (dependent) upon the
emission of a response.
E.G., A dog learns that a doggy treat is contingent upon
posturing into the “begging” position
Instrumental Conditioning
Instrumental Conditioning was first defined and studied
by E. L. Thorndike
The Law of Effect (Thorndike)
The likelihood and strength of a behavior are
determined by the consequences it produces.
If a behavior is followed by a positive state of affairs,
the response becomes stronger (reward training).
The term “Reinforcement” is used to refer to any
stimulus which has the capability to strengthen behavior
If a behavior is followed by a negative state of affairs, the
response becomes weaker (punishment).
Such negative stimuli are referred to as being “Aversive”.
Administration of negative and positive stimuli creates four
distinct Instrumental Conditioning Training Paradigms.
The Asymmetrical Law of Effect
The general belief amongst psychologists that reward and
punishment differ significantly in their effectiveness in
modifying behavior
Punishment suppresses behavior but its effects are
diffuse (Suppression affects all behaviors, not just
the punished behavior).
Punishment produces disruptive negative
emotionality.
Punished behaviors show a large spontaneous
recovery.
Instrumental Conditioning Paradigms
Nature of the Stimulus
Target Response
Causes Application
of the Stimulus
Target Response
Prevents or Causes
Removal of the
Stimulus
Positive
Negative
Positive
Reinforcement
Punishment
(Appetitive
Conditioning)
(Aversive
Conditioning)
Negative
Reinforcement
Omission
(Escape or
Avoidance)
The Cumulative Response Record
Variables Influencing Instrumental Conditioning
Amount of Reinforced Practice
Learning Curve
Negatively Accelerated
Asymptote
Variables Influencing Instrumental Conditioning
Amount of Reinforced Practice
Amount of Reinforcement
Large
Magnitude
of Reward
Small
Magnitude of
Reward
Variables Influencing Instrumental Conditioning
Amount of Reinforced Practice
Amount of Reinforcement
Quality of Reward
Delay of Reward
Reinforcement Schedule
Schedules of Reinforcement
CRF (Continuous Reinforcement) – Each response is
followed by reward.
p (reward) = 1.0
EXT (Extinction) – Each response followed by no reward
p (reward) = 0.0
PR (Partial Reward) – Responses are followed by reward
with a probability greater than 0 but less than 1.
50% PR schedule would mean subjects would be
reinforced on a random ½ of their trials
The Partial Reinforcement Effect (PRE)
CRF
PR