Operant Conditioning
Thomas G. Bowers, Ph.D.
Penn State Harrisburg
Operant Conditioning
Thought to operate upon the
environment
 So-called “voluntary behavior”
 Thorndike aimed to explain goal
directed behavior

– Developed Law of Effect
Law of Effect
Behavior is sensitive to its
consequences
 Positive reinforcement - Pleasurable
consequences stamp in the behavior
 Punishment - Unpleasant events stamp
out the behavior

Behavior-consequence
Relationship
Positive reinforcement acts to increase
the probability of behavior
 Punishment acts to decrease the
probability of behavior

Behavior-consequence
Relationship
Negative reinforcement (or escape) acts
to increase behavior which eliminates or
removes the negative stimulus
 Omission removal of a positive stimulus
decreases behavior

Response-consequence
Relationships
Stimulus
Positive
Reinforcement
Punishment
Omission
Escape or
Avoidance
Response
Conditioning and Extinction
Responses are developed by a shaping
process of successive approximations
 Extinction refers to the cessation of
reinforcement

Behavioral Units
•Acquisition
Extinction
Response/Min
Time
Contingency Learning
1.0
P(Sr/R)
.0
P(Sr/No Res)
1.0
Operant Contingency Space
Reinforcement has a contingent effect,
increasing behavior, while punishment
or even non-reinforcement will decrease
behavior
 When reinforcement and responses are
independent, or noncontingent, then
learned helplessness results

Operant Contingency Space
Learned helplessness resembles
depression
 Seligman developed the paradigm
 Leads to a global failure to initiate
behavior
 Associated with depletion of
monoamine neurotransmitters

Operant Conditioning
What is learned?
 R - S relationship?
 How can something temporally remote
(i.e. following) cause an event?
 Some theorists emphasize S - R
relationships

Avoidance Behavior
Much of our day to day behavior may
serve to avoid negative or aversive
stimuli or consequences
 Signaled avoidance trials

– Early training does not avoidance, but
escapes the stimulus
– Latency tends to decrease
Avoidance Behavior

Shock postponement procedure
– Also called free-operant avoidance
– Sidman avoidance

Most animals manage to learn this well,
with few actual shocks experienced
Theories of Avoidance

Does the animal “know”?
Theories of Avoidance

Two factor theory - Mowrer
– Initial learning by reinforcement of escape
behavior
– Classical conditioning also occurring, and
CS acquires fear eliciting properties
– Response here is reinforced by fear (CS)
removal
– Avoidance behavior results
Theories of Avoidance
Tests to inhibitory procedures appear to
confirm predictions
 Some problems, though

– animals will respond reliably even if only a
reduction of shock frequency is the
contingency
– there is little evidence of conditioned fear
in well-trained animals
Theories of Avoidance

Some problems, though
– avoidance of extinction
– avoidance can be extinguished, but by
response blocking
Cognitive Theories

Expectancy theory
– Organism prefers no shock to shock
– Organism expects if it responds, no shock
will occur
– Organism expects if it does not respond,
shock will occur
– Expectancies are strengthened when
confirmed, weakened when disconfirmed
Cognitive Theories

Expectancy theory
– Probability of avoidance increases as the
degree of confirmation increases
Biological Theories
Bolles emphasized the adaptive
significance to persistent avoidance
learning
 Described a repertoire of defensive
reactions
 Species-specific defensive reactions
(SSDR)

Biological Theories
Hierarchical organization
 Some patterns of responses are much
easier to acquire than others

Conditioned Reinforcement
Neutral stimuli can also become a
conditioned reinforcer
 Predictiveness, informativeness is
important to becoming a secondary
reinforcer
 Animals will respond for the opportunity
to gain informative stimulus conditions

Applications of Secondary
Reinforcement

Token economies
– Common in our environment
– Generalized secondary reinforcers
– Functions



Provide feedback
Provide information about what to do next
Serve to bridge long gaps in reinforcement
– Economies now build in inflation