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Chapter 6
Learning and Behavior
Learning

A more or less permanent change in
behavior that results from experience
Behavior

The ways in which animals act or
respond in an environment
– influenced by both biological and learned
components
Richard Dawkins: Memes


A cultural invention that is passed on
from one generation to the next
Marvin Harris (1974)
– “Our primary mode of biological adaptation
is cultural not anatomical”
Ivan Pavlov

Learning is an associative process
– Pavlov studied a learned association
between a neutral stimulus and a reflexive
response
Classical Conditioning

US - Unconditioned Stimulus
– stimulus that evokes the behavioral
response of interest (Meat powder)

UR - Unconditioned Response
– the reflexive response to the presentation
of the US (Salivation)

NS - Neutral Stimulus
– a stimulus that does not result in an
unconditioned response (Bell)
Classical Conditioning
Before Conditioning
NS (Bell)
produces
produces
No UR
(No Salivation)
Classical Conditioning
Before Conditioning
NS (Bell)
produces
No UR
(No Salivation)
produces
US (Meat)
produces
produces
UR (Salivation)
Classical Conditioning
During Conditioning Trial 1
NS (Bell)
+
US (Meat)
produces
+
produces
UR (Salivation)
Classical Conditioning
During Conditioning Trial 2
NS (Bell)
+
US (Meat)
produces
+
produces
UR (Salivation)
Classical Conditioning
During Conditioning Trial 3
NS (Bell)
+
US (Meat)
produces
+
produces
UR (Salivation)
Classical Conditioning
During Conditioning Trial 4
NS (Bell)
+
US (Meat)
produces
+
produces
UR (Salivation)
Classical Conditioning
After Conditioning
CS (Bell)
produces
produces
CR (Salivation)
Classical Conditioning

CS - Conditioned Stimulus (Bell)
– what used to be called the neutral stimulus.
• Initially it evoked no response, but, after
conditioning, it now evokes a response

CR - Conditioned Response (Salivation)
– similar (but often not identical to) the
unconditioned response
• but is evoked by the conditioned stimulus
Habituation and Sensitization


Can animals learn without association?
Habituation
– Decreased responsiveness to repeated
stimulation

Sensitization
– Increased responsiveness following a
single stimulus presentation
Extinction

A reduction in the conditioned response
when the conditioned stimulus is
presented without the unconditioned
stimulus
– e.g. presenting the bell repeatedly without
the meat will eventually eliminate the
salivation
Spontaneous Recovery

The reappearance of the conditioned
responses following a delay in the
extinction process
Acquisition
Bell+Meat
24 Hour Delay
CR: Drops of Saliva
Extinction
Bell Only
Trials
Spontaneous
Recovery
Bell Only
Higher Order Conditioning

First Order Conditioning:
– Associating Bell + Meat Powder eventually
leads to salivation to Bell alone (Bell =
CS1)

Higher Order Conditioning
– Associate CS1 with a new CS (e.g. Light)
– Associating Bell + Light eventually leads to
salivation to Light alone (Light = CS2)
Higher Order Conditioning
During Conditioning
CS1 (Bell)
+
NS (Light)
produces
+
produces
CR (Salivation)
Higher Order Conditioning
After Conditioning
CS2 (Light)
produces
CR (Salivation)
produces
Important:
The Light is never directly
associated with meat
Basic Rules of Conditioning




The more association trials, the better
the conditioning
CS and US must be closely linked in
time
Physically intense stimuli are
conditioned more easily
Some things are more easily
conditioned than others
Stimulus Generalization
and Discrimination

Stimulus Generalization
– Animals will show a Conditioned Response
to stimuli similar to the original CS
Stimulus Generalization
and Discrimination

Discrimination
– If you repeatedly associate one CS with
the US and do not associate the second,
the CR will discriminate the two
CS+
CS-
Figure 6.4
Real-Life Examples
of Classical Conditioning

Conditioning Emotional Responses
– Baby Albert (Watson and Rayner, 1920)
• Conditioned fear to a white rat by
associating a loud noise with the rat
– CS = rat
– US = loud noise
– UR = startle to loud noise
– CR = startle to rat
Real-Life Examples
of Classical Conditioning

Learning the meaning of words
– Word is associated with the sensory
impression
• e.g. “apple” and view of an apple
– “Second-signal system”
Real-Life Examples
of Classical Conditioning

Conditioned Taste Aversion
– a taste (CS) associated with a toxin (US)
leads to nausea (UR)
– later, the taste alone evokes nausea (CR)
Real-Life Examples
of Classical Conditioning

Drug Tolerance
– drug users become increasingly less
responsive to the effects of the drug
– tolerance is specific to specific
environments (e.g. bedroom)
– familiar environment becomes associated
with a compensatory response
• taking drug in unfamiliar environment leads to
lack of tolerance
Instrumental Learning

Pavlov
– Classical conditioning of reflexes

Can learning occur with nonreflexive
behavior?
– Instrumental Response: a voluntary
response that acts on the environment in a
meaningful way
Instrumental Learning

The modification of instrumental
responses using reinforcers and
punishers
E.L. Thorndike’s Puzzle Box


Cat placed in a box that can be opened from
inside by pushing on latch
Initially, cat shows random behaviors
– scratching
– sniffing

Eventually cat will hit latch
– hitting latch leads to pleasant
consequence - escape
• increases likelihood action will occur again
Thorndike’s Law of Effect


Responses followed by “satisfiers” tend
to be repeated
Those followed by “annoyers” are not
repeated
– useful behaviors are stamped in
Operants

B.F. Skinner:
– An operant is an instrumental response
that operates on the environment

Positive Reinforcer
– Any stimulus that increases the likelihood
of an operant response

Skinner developed a general model of
learning called “operant conditioning”
The Operant
Chamber
Shaping Behavior

Reinforce
responses that
approximate
the target
behavior
Secondary Reinforcement

Neutral stimuli can acquire reinforcing
properties through the process of
higher-order conditioning
– e.g. the reinforcing effect of language
(“good boy”)
Schedules of Reinforcement


Rate at which reinforcer is delivered
influences nature of response
Continuous reinforcer
– each response is reinforced

Partial Reinforcement
– reinforcer is not delivered for each
response
Partial Reinforcement

Fixed Ratio (FR) Schedule
– reinforcer is delivered only after a fixed
number of responses have been made
• e.g. FR-10 schedule: reinforcer
delivered after every 10th lever press
Partial Reinforcement

Variable Ratio (VR) Schedule
– the number of responses before a
reinforcer is delivered varies
Partial Reinforcement

Fixed Interval (FI) Schedule
– the first response following a specified time
interval is reinforced
• e.g. FI-10 schedule: only responses
made after 10 seconds are reinforced
Partial Reinforcement

Variable Interval (VI) Schedule
– the first response following a varying time
interval is reinforced
Partial Reinforcement affects
Response Rate
Partial Reinforcement Effect


If you train an animal using partial
reinforcement, it is more resistant to
extinction than one that received
continuous reinforcement
Extinction
– a reduction in the rate of response when a
reinforcer is withheld
Differential Reinforcement

Differential Reinforcement of a High
Rate of Response (DRH)
– reinforce bursts of responses

Differential Reinforcement of a Low
Rate of Response (DRL)
– reinforce pauses between responses
Behavioral Control


Skinner:
– The likelihood of any behavior
depends on reinforcement and
punishment contingencies
Environmental Determinism
– environmental stimuli exert total
control over behavior
Stimulus Control

The Discriminative Stimulus (Sd)
– a signal that indicates when a response will
be reinforced
• e.g. reinforcing lever pressing only when light is
on

Negative Discriminative Stimulus (S)
– A signal that indicates that a response will
not be followed by reinforcement
Stimulus Control

Responding only in the presence of Sd
and not in the presence of S
Punishment

Another potential consequence of
behavior
– An aversive stimulus that decrease the rate
of responding

When is punishment most effective?
– It must be relatively intense
– It must follow the response relative quickly
– It must be applied consistently
Negative Reinforcement

Any stimulus whose withdrawal
increases the probability of a behavior
– e.g. pushing a lever to turn off a shock

Avoidance Learning
– when an instrumental response prevents
and aversive stimulus
• e.g. pushing a lever before the onset of shock
Persistence of
Avoidance Learning

Negatively reinforced responses show
slower extinction than positively
reinforced responses
– avoidance learning - gaining both positive
reinforcement and avoiding punishment
Observational Learning


Not all learning occurs through direct
reinforcement
We can learn by watching others and
through imitation
Limitations to Pavlov’s and
Skinner’s Theories of Learning

Instinctive Drift
– Animals will often show instinctive
behaviors even if they are not being
reinforced
• e.g. raccoons “washing” coins
Limitations to Pavlov’s and
Skinner’s Theories of Learning

Cognitive Maps
– Animals can create a mental
representation of a maze even if they
haven’t been reinforced to solve the maze
Limitations to Pavlov’s and
Skinner’s Theories of Learning

Latent learning
– when animals that
have not been
reinforced are
reinforced, they
show faster than
expected learning
Limitations to Pavlov’s and
Skinner’s Theories of Learning

Preparedness
– some associations are learned more easily
than others
• e.g. associating taste with nausea is easier
than associating noise with nausea
Conceptual Learning

Do associations or reinforcement
explain all types of learning?

Learning to learn:
– some animals can learn strategies
– win-stay, lose-shift: continue response if
reinforced, switch response if not
reinforece
Behavioral Complexity and
Environmental Complexity

The more complex the behavior, the
more complex the environment required