Quiz #3Last class, we talked about 6 techniques for

self-control. Name and briefly describe 2 of those techniques.

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Schedules of Reinforcement

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Schedule of ReinforcementDelivery of reinforcementContinuous reinforcement (CRF)Fairly consistent patterns of behaviourCumulative recorder

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Cumulative RecordUse a cumulative recorderNo response: flat lineResponse: slopeCumulative record

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paper strip

pen

roller roller

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6

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VI-25

Schedules:4 Basic:

Fixed RatioVariable RatioFixed IntervalVariable Interval

Others and mixes (concurrent)

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Fixed Ratio (FR)N responses required; e.g., FR 25CRF = FR1Rise-and-runPostreinforcement pauseSteady, rapid rate of responseRation strain

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Time

no responses

reinforcement

responses“pen” resetting

slope

Variable Ratio (VR)Varies around mean number of responses; e.g.,

VR 25Rapid, steady rate of responseShort, if any postreinforcement pause

Longer schedule --> longer pauseNever know which response will be reinforced

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Fixed Interval (FI)Depends on time; e.g., FI 25Postreinforcement pauseScallopingTime estimationClock doesn’t start until reinforcer given

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Variable Interval (VI)Varies around mean time; e.g., VI 25Steady, moderate response rateDon’t know when time has elapsedClock doesn’t start until reinforcer given

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FR 25

VR 25

FI 25

VI 25

75

50

25

VR FR VI FI

Slope = rise

run

Duration SchedulesContinuous responding for some time period

to receive reinforcementFixed duration (FD)

Period of duration is a set time periodVariable duration (VD)

Period of duration varies around a mean

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Differential Rate SchedulesDifferential reinforcement of low rates (DRL)

Reinforcement only if X amount of time has passed since last response

Sometimes “superstitious behaviours” occurDifferential reinforcement of high rates (DRH)

Reinforcement only if more than X responses in a set time

Or, reinforcement if less that X amount of time has passed since last response

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Noncontingent SchedulesReinforcement delivery not contingent upon a

response, but on passage of timeFixed time (FT)

Reinforcer given after set time elapsesVariable time (VT)

Reinforcer given after some time varying around a mean

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Stretching the RatioIncreasing the number of responsese.g., FR 5 --> FR 50Extinction problemUse shapingIncrease in gradual incrementse.g., FR 5, FR 8, FR 14, FR 21, FR 35, FR 50“Low” or “high” schedules

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ExtinctionCRF (FR 1) easiest to extinguish than

intermittent schedules (anything but FR 1)Partial reinforcement effect (PRE)High schedules harder to extinguish than lowVariable schedules harder to extinguish than

fixed

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Discrimination HypothesisDifficult to discriminate between extinction

and intermittent scheduleHigh schedules more like extinction than low

schedulese.g., CRF vs. FR 50

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Frustration HypothesisNon-reinforcement for response is frustratingOn CRF every response reinforced, so no

frustrationFrustration grows continually during

extinctionStop responding, stop frustration (neg. reinf.)

Any intermittent schedule always some non-reinforced responsesResponding leads to reinforcer (pos. reinf.)Frustration = S+ for reinforcement

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Sequential HypothesisResponse followed by reinf. or nonreinf.On intermittent schedules, nonreinforced

responses are S+ for eventual delivery of reinforcer

High schedules increase resistance to extinction because many nonreinforced responses in a row leads to reinforced

Extinction similar to high schedule

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Response Unit HypothesisThink in terms of behavioural “units”FR1: 1 response = 1 unit --> reinforcementFR2: 2 responses = 1 unit --> reinforcement

Not “response-failure, response-reinforcer” but “response-response-reinforcer”

Says PRE is an artifact

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Mowrer & Jones (1945)

Response unit hypothesis

More responses in extinction on higher schedules disappears when considered as behavioural units

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300

250

200

150

100

50

Nu

mb

er o

f re

spon

ses/

un

its

du

rin

g ex

tin

ctio

n

FR1 FR2 FR3 FR4

absolute number of responses

number of behavioural units

Complex SchedulesMultipleMixedChainTandemcooperative

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ChoiceTwo-key procedure

Concurrent schedules of reinforcementEach key associated with separate scheduleDistribution of time and behaviour

The measure of choice and preference

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Concurrent Ratio SchedulesTwo ratio schedulesSchedule that gives most rapid reinforcement

chosen exclusivelyRarely used in choice studies

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Concurrent Interval SchedulesMaximize reinforcementMust shift between alternativesAllows for study of choice behaviour

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Interval SchedulesFI-FI

Steady-state respondingLess useful/interesting

VI-VINot steady-state responding

Respond to both alternatives Sensitive to rate of reinforcemenet

Most commonly used to study choice

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Alternation and the Changeover ResponseMaximize reinforcers from both alternativesFrequent shifting becomes reinforcing

Simple alternationConcurrent superstition

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Changeover DelayCODPrevents rapid switchingTime delay after “changeover” before

reinforcement possible

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Herrnstein’s (1961) ExperimentConcurrent VI-VI schedulesOverall rates of reinforcement held

constant40 reinforcers/hour between two

alternatives

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The Matching LawThe proportion of responses directed toward

one alternative should equal the proportion of reinforcers delivered by that alternative.

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Key 1

Key 2

VI-3minRein/hour = 20

Resp/hour = 2000

VI-3minRein/hour = 20

Resp/hour = 2000

Proportional Rate of Reinforcement

R1 = reinf. on key 1R2 = reinf. on key 2

R1

R1+R2

= 2020+20

= 0.5

Proportional Rate of Response

B1 = resp. on key 1B2 = resp. on key 2

B1

B1+B2

= 20002000+2000

= 0.5

MATCH!!!

Key 1

Key 2

VI-9minRein/hour = 6.7Resp/hour = 250

VI-1.8minRein/hour = 33.3Resp/hour = 3000

Proportional Rate of Reinforcement

R1 = reinf. on key 1R2 = reinf. on key 2

R1

R1+R2

= 6.76.7+33.3

= 0.17

Proportional Rate of Response

B1 = resp. on key 1B2 = resp. on key 2

B1

B1+B2

= 250250 + 3000

= 0.08

NO MATCH (but close…)

BiasSpend more time on one alternative than

predictedSide preferencesBiological predispositionsQuality and amount

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Varying Quality of ReinforcersQ1: quality of first reinforcerQ2: quality of second reinforcer

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Varying Amount of ReinforcersA1: amount of first reinforcerA2: amount of second reinforcer

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Combining Qualities and Amounts

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ApplicationsGambling

Reinforcement historyEconomics

Value of reinforcer and stretching the ratioMalingering

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