Schedules of Reinforcement Thomas G. Bowers, Ph.D.

Schedules of Schedules of Reinforcement Reinforcement

Thomas G. Bowers, Ph.D.Thomas G. Bowers, Ph.D.

How is behavior How is behavior maintained?maintained?

Simplistic to simply think Simplistic to simply think uncomplicated contingencies uncomplicated contingencies operate in the day to day operate in the day to day environmentenvironment

Patterns of reinforcement, patterns Patterns of reinforcement, patterns of conditioning, relate in a complex of conditioning, relate in a complex fashion with the characteristics of fashion with the characteristics of the organismthe organism


Yield predictable and orderly Yield predictable and orderly patterns of behavioral responsespatterns of behavioral responses

Most patterns of reinforcement are Most patterns of reinforcement are intermittentintermittent

More recently, theorists have also More recently, theorists have also attended to the economic aspects attended to the economic aspects of intermittent reinforcementof intermittent reinforcement


Basic SchedulesBasic Schedules• 1. Fixed Interval Schedules (FI)1. Fixed Interval Schedules (FI)

– A single response after the passage of a fixed A single response after the passage of a fixed period of time yields reinforcementperiod of time yields reinforcement

– Responses during the interval are not reinforcedResponses during the interval are not reinforced

• 2. Variable Interval Schedules (VI) 2. Variable Interval Schedules (VI) – A single response after a varied passage of timeA single response after a varied passage of time– e.g. VI2 - after an average passage of 2 minutes e.g. VI2 - after an average passage of 2 minutes


Basic SchedulesBasic Schedules• 3. Fixed Ratio (FR)3. Fixed Ratio (FR)

– Reinforcement occurs after a fixed number Reinforcement occurs after a fixed number of responsesof responses

– Passage of time irrelevantPassage of time irrelevant

• 4. Variable Ratio (VR)4. Variable Ratio (VR)– Number of responses required for Number of responses required for

reinforcement vary from trial to trialreinforcement vary from trial to trial– e.g. VR 50 reinforces on the e.g. VR 50 reinforces on the averageaverage the the

50th response50th response


Intermittent reinforcement tends Intermittent reinforcement tends to maintain patterns of responding to maintain patterns of responding for longer periods of time in for longer periods of time in extinctionextinction• partial reinforcement effectpartial reinforcement effect• implies greater response strength implies greater response strength

Schedules of Schedules of ReinforcementReinforcement

CumulativeResponses

Time

VR

VI


CumulativeResponses

Time

FR

FI


Some characteristicsSome characteristics• 1. Variable schedules tend to develop 1. Variable schedules tend to develop

higher rates of responding relative to higher rates of responding relative to fixed schedulesfixed schedules

• 2. Ratio schedules tend to develop higher 2. Ratio schedules tend to develop higher rates of responding to interval schedules rates of responding to interval schedules

• 3. Fixed schedules of reinforcement 3. Fixed schedules of reinforcement demonstrate a characteristic pause after demonstrate a characteristic pause after each reinforcementeach reinforcement


Some characteristicsSome characteristics• 4. Pause of responding after 4. Pause of responding after

reinforcement on fixed ratio/interval reinforcement on fixed ratio/interval is described as post-reinforcement is described as post-reinforcement pause (PRP)pause (PRP)

Choice BehaviorsChoice Behaviors

Study of Concurrent Patterns of Study of Concurrent Patterns of ReinforcementReinforcement• How is behavior demonstrated in the How is behavior demonstrated in the

situation where there are multiple situation where there are multiple schedules of reinforcement schedules of reinforcement operating?operating?

• Organisms respond in direct Organisms respond in direct proportion of the frequency (or proportion of the frequency (or density) of reinforcement offered density) of reinforcement offered

Matching LawMatching Law

Herrnstein and associates in the Herrnstein and associates in the 1970s1970s

Respon ARespon A + Respon B

= Rft ARft A + Rft B


Or, more clearly Or, more clearly

RARA + RB =

rara + rb


Magnitude of reinforcementMagnitude of reinforcement

RaRa + Rb =

MaMa + Mb


Delay of ReinforcementDelay of Reinforcement

RaRa + Rb =

1/Da1/Da + 1/Db


Allows for more complex Allows for more complex processing analysisprocessing analysis

RaRa + Rb =

ra x Ma x 1/Da(ra x Ma x 1/Da) + (rb x mb x1/Db)

Matching Law Matching Law

Animals tend to respond Animals tend to respond differentially, with more responses differentially, with more responses to the smaller immediate reward to the smaller immediate reward relative to the larger delayed relative to the larger delayed rewardreward

Choice BehaviorsChoice Behaviors

Immediacy of reinforcement can Immediacy of reinforcement can “lock in” an organism to a leaner “lock in” an organism to a leaner schedule of reinforcementschedule of reinforcement

Matching and MaximizingMatching and Maximizing

Maximizing suggests the animal Maximizing suggests the animal will demonstrate the response will demonstrate the response which maximizes the likelihood of which maximizes the likelihood of reinforcementreinforcement

This is somewhat different than This is somewhat different than predicted by matching predictionspredicted by matching predictions

Matching and Maximizing Matching and Maximizing

Animals tend to distribute Animals tend to distribute responses in relation to the density responses in relation to the density of reinforcementof reinforcement

This is even true when some This is even true when some patterns results in less over all patterns results in less over all reinforcementreinforcement

Matching and MaximizingMatching and Maximizing

This effect has been attempted to be This effect has been attempted to be explained by optimal foraging theoryexplained by optimal foraging theory

Feeding behavior is thought to be Feeding behavior is thought to be sensitive to the amount of energy sensitive to the amount of energy expended in finding, securing and expended in finding, securing and eating foodeating food

There may be adaptive significance There may be adaptive significance to seeking varieties of food sources to seeking varieties of food sources

Economic ConceptsEconomic Concepts

DemandDemand• Some demands are elasticSome demands are elastic• Others are inelasticOthers are inelastic• For example, bread is probably For example, bread is probably

inelastic, while movies may be elasticinelastic, while movies may be elastic

Types of EconomiesTypes of Economies

Open versus closed contingent Open versus closed contingent systemssystems• open systems tend to decrease open systems tend to decrease

response ratesresponse rates• holds for both FR and VR schedulesholds for both FR and VR schedules

SummarySummary

Intermittent schedules of reinforcement Intermittent schedules of reinforcement leads to greater response strengthleads to greater response strength

Variable schedules of reinforcement Variable schedules of reinforcement yields higher levels of behavioryields higher levels of behavior

Ratio schedules of reinforcement also Ratio schedules of reinforcement also yield higher levels of behavioryield higher levels of behavior

Interval schedules demonstrate Interval schedules demonstrate characteristic patterns of responding characteristic patterns of responding

SummarySummary

Organisms tend to match Organisms tend to match reinforcement probabilities rather reinforcement probabilities rather than maximize reinforcementthan maximize reinforcement

Economic aspects influence Economic aspects influence patterns of contingent behaviorpatterns of contingent behavior

Schedules of Reinforcement Thomas G. Bowers, Ph.D.

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