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Chapter 6
Learning
Classical conditioning
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Ivan Pavlov
Terminology
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Unconditioned Stimulus (UCS)
Conditioned Stimulus (CS)
Unconditioned Response (UCR)
Conditioned Response (CR)
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Fig 6.1 – Classical conditioning apparatus. An experimental arrangement similar to the one
depicted here (taken from Yerkes & Morgulis, 1909) has typically been used in demonstrations
of classical conditioning, although Pavlov’s original setup (see inset) was quite a bit simpler.
The dog is restrained in a harness. A tone is used as the conditioned stimulus (CS), and the
presentation of meat powder is used as the unconditioned stimulus (UCS). The tube inserted
into the dog’s salivary gland allows precise measurement of its salivation response. The pen
and rotating drum of paper on the left are used to maintain a continuous record of salivary flow.
(Inset) The less elaborate setup that Pavlov originally used to collect saliva
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on each trial is shown here (Goodwin, 1991).
Fig 6.2 – The sequence of
events in classical
conditioning. (a) Moving
downward, this series of three
panels outlines the sequence of
events in classical conditioning,
using Pavlov’s original
demonstration as an example.
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Fig 6.3 – Classical conditioning of a fear response. Many emotional responses
that would otherwise be puzzling can be explained by classical conditioning. In the
case of one woman’s bridge phobia, the fear originally elicited by her father’s scare
tactics became a conditioned response to the stimulus of bridges.
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Classical Conditioning: More Terminology
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Trial = pairing of UCS and CS
Acquisition = initial stage in learning
Stimulus contiguity = occurring together in time and
space
3 types of Classical Conditioning
– Simultaneous conditioning: CS and UCS begin and end
together
– Short-delayed conditioning: CS begins just before the UCS,
end together
– Trace conditioning: CS begins and ends before UCS is
presented
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Processes in Classical Conditioning
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Extinction
 Spontaneous Recovery
 Stimulus Generalization
 Discrimination
 Higher-order conditioning
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Fig 6.9 – Acquisition, extinction, and spontaneous recovery. During acquisition, the
strength of the dog’s conditioned response (measured by the amount of salivation)
increases rapidly and then levels off near its maximum. During extinction, the CR declines
erratically until it’s extinguished. After a “rest” period in which the dog is not exposed to the
CS, a spontaneous recovery occurs, and the CS once again elicits a (weakened) CR.
Repeated presentations of the CS alone re-extinguish the CR, but after Table of Contents
another “rest” interval, a weaker spontaneous recovery occurs.
Fig 6.10 – The conditioning of Little Albert. The diagram shows how Little Albert’s
fear response to a white rat was established. Albert’s fear response to other white,
furry objects illustrates generalization.
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Fig 6.12 – Higher-order conditioning. Higher-order conditioning is a two-phase
process. In the first phase, a neutral stimulus (such as a tone) is paired with an
unconditioned stimulus (such as meat powder) until it becomes a conditioned
stimulus that elicits the response originally evoked by the UCS (such as
salivation). In the second phase, another neutral stimulus (such as a red light) is
paired with the previously established CS, so that it also acquires the capacity to
elicit the response originally evoked by the UCS.
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Operant Conditioning or Instrumental
Learning
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Edward L. Thorndike (1913) – the law of effect
B.F. Skinner (1953) – principle of reinforcement
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Operant chamber
Emission of response
Reinforcement contingencies
Cumulative recorder
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Fig 6.14 – Reinforcement in operant conditioning. According to Skinner, reinforcement
occurs when a response is followed by rewarding consequences and the organism’s
tendency to make the response increases. The two examples diagrammed here illustrate the
basic premise of operant conditioning—that voluntary behavior is controlled by its
consequences. These examples involve positive reinforcement (for a comparison of positive
and negative reinforcement, see Figure 6.21).
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Fig 6.15 – Skinner box and cumulative recorder. (a) This diagram highlights some of the key features of an
operant chamber, or Skinner box. In this apparatus designed for rats, the response under study is lever pressing.
Food pellets, which may serve as reinforcers, are delivered into the food cup on the right. The speaker and light
permit manipulations of visual and auditory stimuli, and the electric grid gives the experimenter control over aversive
consequences (shock) in the box. (b) A cumulative recorder connected to the box keeps a continuous record of
responses and reinforcements. Each lever press moves the pen up a step, and each reinforcement is marked with a
slash.
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Basic Processes in Operant Conditioning
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Acquisition
 Shaping
 Extinction
 Stimulus Control
– Generalization
– Discrimination
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Fig 6.16 – A graphic
portrayal of operant
responding. The
results of operant
conditioning are often
summarized in a
graph of cumulative
responses over time.
The insets magnify
small segments of
the curve to show
how an increasing
response rate yields
a progressively
steeper slope
(bottom); a high,
steady response rate
yields a steep, stable
slope (middle); and a
decreasing response
rate yields a
progressively flatter
slope (top).
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Reinforcement: Consequences that
Strengthen Responses
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Delayed Reinforcement
– Longer delay, slower conditioning
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Primary Reinforcers
– Satisfy biological needs
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Secondary Reinforcers
– Conditioned reinforcement
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Schedules of Reinforcement
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Continuous reinforcement
Intermittent (partial) reinforcement
Ratio schedules
– Fixed
– Variable
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Interval schedules
– Fixed
– Variable
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Fig 6.19 – Schedules of reinforcement and patterns of response. Each type of reinforcement
schedule tends to generate a characteristic pattern of responding. In general, ratio schedules
tend to produce more rapid responding than interval schedules (note the steep slopes of the FR
and VR curves). In comparison to fixed schedules, variable schedules tend to yield steadier
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responding (note the smoother lines for the VR and VI schedules on the
right) and greater resistance to extinction.
Consequences: Reinforcement and
Punishment
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Increasing a response:
– Positive reinforcement = response followed by rewarding
stimulus
– Negative reinforcement = response followed by removal of
an aversive stimulus
• Escape learning
• Avoidance learning
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Decreasing a response:
– Punishment
– Problems with punishment
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Fig 6.21 – Positive reinforcement versus negative reinforcement. In positive reinforcement,
a response leads to the presentation of a rewarding stimulus. In negative reinforcement, a
response leads to the removal of an aversive stimulus. Both types of reinforcement involve
favorable consequences and both have the same effect on behavior: The organism’s tendency
to emit the reinforced response is strengthened.
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Fig 6.22 – Escape and avoidance
learning. (a) Escape and avoidance
learning are often studied with a
shuttle box like that shown here.
Warning signals, shock, and the
animal’s ability to flee from one
compartment to another can be
controlled by the experimenter. (b)
According to Mowrer’s two-process
theory, avoidance begins because
classical conditioning creates a
conditioned fear that is elicited by the
warning signal (panel 1). Avoidance
continues because it is maintained
by operant conditioning (panel 2).
Specifically, the avoidance response
is strengthened through negative
reinforcement, since it leads to
removal of the conditioned fear.
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Fig 6.23 – Comparison of negative reinforcement and punishment. Although punishment can
occur when a response leads to the removal of a rewarding stimulus, it more typically involves the
presentation of an aversive stimulus. Students often confuse punishment with negative
reinforcement because they associate both with aversive stimuli. However, as this diagram
shows, punishment and negative reinforcement represent opposite procedures Table of Contents
that have opposite effects on behavior.
Changes in Our Understanding of
Conditioning
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Biological Constraints on Conditioning
– Instinctive Drift
– Conditioned Taste Aversion
– Preparedness and Phobias
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Cognitive Influences on Conditioning
– Signal relations
– Response-outcome relations
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Evolutionary Perspectives on learning
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Fig 6.24 – Conditioned taste aversion. Taste aversions can be established
through classical conditioning, as in the “sauce béarnaise syndrome.” However,
as the text explains, taste aversions can be acquired in ways that seem to
violate basic principles of classical conditioning.
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Observational Learning: Basic Processes
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Albert Bandura (1977, 1986)
– Observational learning
– Vicarious conditioning
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4 key processes
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attention
retention
reproduction
motivation
acquisition vs. performance
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Fig 6.26 – Observational learning. In observational learning, an observer
attends to and stores a mental representation of a model’s behavior (example:
assertive bargaining) and its consequences (example: a good buy on a car). If the
observer sees the modeled response lead to a favorable outcome, the observer’s
tendency to emit the modeled response will be strengthened.
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