B.F. Skinnner Radical and then Modern Behaviorism.

B.F. Skinnner

Radical and then Modern Behaviorism

Burris Fredric Skinner

Burris Frederic Skinner• Born in Pennsylvania

• BA degree in English from Hamilton College• Masters/PhD from Harvard in 1930, 1931

• Taught at Univ of Minnesota 1936-1945– Behaviors of Organisms, 1938

• 1945 to Indiana University• 1948 to Harvard; there until his death in 1990

• Several important “human rights” books– Beyond Freedom and Dignity– Walden Two– Enjoy Old Age

• 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

• correlated 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: if the occurrence of an operant is followed by a presentation of a reinforcing stimulus, the strength is increased

• -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

• 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

• 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: with 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!

• 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:

– 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• S = stimulus• R = response• S.R = respondent• SR = reinforcer

• properties of term indicated with lower letters:– 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• Measuring the Behavior:

• important characteristics of measurement:

• definition of behavior as that part of activity of the organism which affects the external world

• the practical isolation of the unit of behavior

• definition of a reponse as a class of events

• demonstration that the rate of responding is the principal measure of the strength of an operant

• cumulative record• Responses accrue or are cumulative• What happens if the line goes down?

Reinforcers vs. PunishersPositive 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 Positive Reinforcement (Positive) PunishmentAdd make bed-->10cent hit sister->spankedStimulus

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 response-

contingency 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 RP 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: RSr

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– 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.