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B.F. Skinnner
Radical and then Modern
Behaviorism
Burris Fredric Skinner
Burris Frederic Skinner
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Born in Pennsylvania
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BA degree in English from Hamilton College
Masters/PhD from Harvard in 1930, 1931
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Taught at Univ of Minnesota 1936-1945
– Behaviors of Organisms, 1938
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1945 to Indiana University
1948 to Harvard; there until his death in 1990
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Several important “human rights” books
– Beyond Freedom and Dignity
– Walden Two
– Enjoy Old Age
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2 daughters: one is psychologist Julie Vargas (runs autism program at WVU) and a
pianist
Why Behaviorism
• Defines "behavior" as what the animal is
(observed to be) doing.
– Avoid anthropomorphizing or implying conceptual
schemes
– Simply describe what the animal is doing
• Avoids preconceived notions and concepts
about the animal's behavior
Narration as a descriptor:
defining what is behavior
• Narrate what the animal is doing- running frame of reference
• “Stimulus” refers to environment: Subscripts tell what part of the
environment
– SD: the discriminative stimulus
– SR: The reinforcing stimulus, or the reinforcer
• Correlated or observed behavior is the response
• Reflex = observed relation between the stimulus and response
– Implies lawfulness
– Is a fact, not a theory
• Not want to "botanize" - but come up with general laws of behavior
Several laws of classical conditioning
• Uses to distinguish from operant behavior
• Static laws of the Reflex: Really discussing classical conditioning here
– Law of threshold: the intensity of the stimulus must reach or exceed a certain
critical value in order to elicit a response
– Law of latency: an interval of time elapses between the beginning of the
stimulus and the beginning of the response
– Law of magnitude of the response: the magnitude of the response is a
function of the intensity of the stimulus
– Law of after discharge: the response may persist for some time after the
cessation of the stimulus
– Law of temporal summation: prolongation of a stimulus or repetitive
presentation within certain limiting rates has the same effect as increasing the
intensity
Several laws of classical conditioning
• Dynamic laws of reflex strength:
– Law of refractory phase: immediately after eliciation the strength of some
reflexes exists at a low, perhaps zero, value. It returns to its former state
during subsequent activity
– Law of reflex fatigue: the strength of a reflex declines during repeated
elicitation and returns to its former value during subsequent inactivity
– Law of facilitation: the strength of a reflex may be increased through
presentation of a second stimulus which does not itself elicit the
response
– Law of inhibition: the strength of a reflex may be decreased through the
presentation of a second stimulus which has no other relation to the effector
involved
• Also discusses law of conditioning of Type S and law of extinction of Type S
Distinguishes between
PAVLOVIAN and OPERANT conditioning
• Operant behavior is EMITTED not elicited
• static laws DO NOT apply to operant behavior
• Remember: still in day when CC does NOT equal
OC
– Believed were different kinds of learning
– CC: visceral muscles
– OC: skeletal responses
Dynamic laws of Type R behavior:
• HIS version of the Law of Effect
• Law of conditioning of Type R behavior: If the occurrence of an
operant is followed by a presentation of a reinforcing stimulus, the
strength is increased
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-notice that conditioning = strength of the operant
• Law of extinction of Type R behavior: If the occurrence of an
operant already strengthened through conditioning is not followed
by the reinforcing stimulus, the strength is decreased
• Can get stimuli that are correlated with R-S connections: thus can
set the occasion for the R-S contingency
The reflex reserve:
• Reflex reserve = total available activity for an animal
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There is a relation between
• The number of responses appearing during the extinction of an
operant and
• The number of preceding reinforcements
• Changes in drive do not change the total number of available
responses,
• Although the rate of responding may vary greatly
• Changes in drive change the rate or pattern of responding
• Emotional, facilitative, and inhibitory changes are compensated for
by later changes in strength
Interaction of reflexes:
• Important in that responses not occur in isolation
• Law of compatibility: Two or more responses which do not overlap
topographically may occur simultaneously without interference
• Law of prepotency: When two reflexes overlap topographically, and
the responses are incompatible, one response may occur to the
exclusion of another
• Law of algebraic summation: The simultaneous elicitation of two
responses utilizing the same effectors but in opposite directions
produces a response the extent of which is an algebraic resultant
Interaction of reflexes:
• Law of blending: Two responses showing some topographical
overlap may be elicited together but in necessarily modified forms
• Law of spatial summation: When two reflexes have the same form
of response, the response to both stimuli in combination has a
greater magnitude and a shorter latency
• Law of chaining: The response of one reflex may constitute or
produce the eliciting or discriminative stimulus of another
• Law of induction: A dynamic change in strength of a reflex may be
accompanied by a similar but not so extensive change in a related
reflex, where the relation is due to the possession of some common
properties of stimulus or response
Defines properties of a class of a reflex
• Under what conditions does the R occur?
– In operant conditioning: what are the defining characteristics for
reinforcement
– Under what stimulus conditions does a response occur?
– What are the results?
– Really the ABCs of operant behavior!
– Antecedants
– Behavior
– Consequences
• What does the animal DO to get reinforced
– Must show a correlation between R and S
– We will argue later that this must be a contingency!
– Must show that dynamic laws apply
Defining Skinner's methodology:
• Direction of inquiry:
– Inductive rather than deductive
– Hypotheses declared to direct the choice of facts
– Not necessary, but guide what is a useful vs useless fact
• The organism:
– Skinner wants to limit to one single representative sample
– The white rat and/or pigeon- many advantages in terms of control
• The operant:
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Use bar pressing
Skinner box
Again- assume that is equivalent to any other response
Easy to measure- reliable, controllable, etc.
Skinner box:
Pigeon pecks or rat bar presses to receive reinforcers
System of notation
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S = stimulus
R = response
S.R = respondent
SR = reinforcer
• Properties of term indicated with lower letters:
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Rabc response with properties a b and c
Superscripts comment upon term- place, formula, etc.
e.g. S1 or SD
also composite stimuli: S1SD
• --> = is followed by
• Now can analyze a chain or sequence of behavior: and string together to
make "behavior sentences"
Important to control
Extraneous Factors
• Use maximal isolation e.g. sound attenuating chamber
• Control "hunger" with deprivation, etc.
– Usually around 80% free feeding
– This is higher today (85-90%)
– Maintains a constant “hunger”
• Standardize feeders and reinforcers
• Control light/day cycles, etc.
• As much experimental control as possible to reduce variance in
experiments
The Cumulative Recorder
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Measuring the Behavior:
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Important characteristics of
measurement:
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Definition of behavior as that part of
activity of the organism which affects
the external world
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The practical isolation of the unit of
behavior
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Definition of a response as a class of
events
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Demonstration that the rate of
responding is the principal measure
of the strength of an operant
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Cumulative record
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Responses accrue or are cumulative
What happens if the line goes down?
Reinforcers vs. Punishers
Positive vs. Negative
• Reinforcer = rate of response INCREASES
• Punisher = rate of response DECREASES
• Positive: something is ADDED to environment
• Negative: something is TAKEN AWAY from
environment
• Can make a 4x4 contingency table
Reinforcement
Punishment
Positive
Add
Stimulus
Positive Reinforcement
make bed-->10cent
(Positive) Punishment
hit sister->spanked
Negative
Negative Reinforcement
Negative Punishment
Remove
make bed-> Mom stops
hit sister->lose TV
Stimulus
nagging
Parameters or Characteristics of
Operant Behavior
• Strength of the response:
– With each pairing of the R and Sr/P, the responsecontingency is strengthened
– The learning curve is
• Monotonically ascending
• Has an asymptote
• There is a maximum amount of responding the
organism can make
Parameters or Characteristics of
Operant Behavior
• Extinction of the response:
– Remove the R Sr or RP contingency
– Now the R  0
• Different characteristics than with classical
conditioning:
– Animal increases behavior immediately after the
extinction begins: TRANSIENT INCREASE
– Animal shows extinction-induced aggression!
– Why?
More parameters:
• Generalization can occur:
– Operant response may occur in situations similar to the one in
which originally trained
– Can learn to behavior in many similar settings
• Discrimination can occur
– Operant response can be trained to very specific stimuli
– Only exhibit response under specific situations
• Can use a cue to teach animal:
– S+ or SD : contingency in place
– S- or S : contingency not in place
– Thus: SD: RSr
Schedules of Reinforcement:
• Continuous reinforcement:
– Reinforce every single time the animal performs the
response
– Use for teaching the animal the contingency
– Problem: Satiation
• Solution: only reinforce occasionally
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Partial reinforcement
Can reinforce occasionally based on time
Can reinforce occasionally based on amount
Can make it predictable or unpredictable
Partial Reinforcement Schedules
• Fixed Ratio: every nth response is reinforced
• Fixed interval: the first response after x amount of
time is reinforced
• Variable ratio: on average of every nth response is
reinforced
• Variable interval: the first response after an
average of x amount of time is reinforced
More parameters
• Shaping
– Final behavior must be within repertoire of organism
– Break behaviors into smallest component
– Chain up or down
• Secondary reinforcement
– Stimuli can be paired with primary reinforcer
– E.g. money
• Generalized reinforcers
– Reinforcers reinforce many behaviors
– E.g., money reinforcers many, many behaviors
• Chaining:
– Make a chain of behaviors
– E.g., 1 behavior leads to another to another to another……makes a chain of
behavior.