psy211 operant conditioning schedules

7/27/2019 PSY211 Operant Conditioning Schedules

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Psychology of Learning

PSY211Operant/Instrumental Conditioning:

Schedules

B. Charles Tatum


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Schedules of Reinforcement

Continuous Reinforcement (CR): A correct response is reinforced every time it

occurs

Intermittent (Partial): Reinforcement occurs for some responses but not all. Ratio: Reinforcement is based on the number of responses (the ratio of

reinforced to non reinforced responses).

Fixed Ratio (FR): The number of reinforced responses is a fixed number

(e.g., FR-2 means every other response is reinforced, FR-10 means every

10th response is reinforced).

Variable Ratio (VR): The number of reinforced responses varies

(e.g., VR-10 means that, on average, every 10th response is

reinforced, but the number can vary)

Interval: Reinforcement is based on the time since the last reinforced response.

Fixed Interval (FI): The amount of time the animal must wait until the next

response is reinforced is fixed (e.g., FI-10 means the animal must waitten seconds after the last reinforced response before the next response

will be reinforced).

Variable Interval (VI): The amount of time the animal must wait until the

next response is reinforced is variable (e.g., VI-10 means the animal must

wait, on average, 10 seconds after the last reinforced response before thenext response is reinforced, but this time can vary).


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Rate from a Cumulative Record

Time

Number ofResponses

(Cumulative

Responses)


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CU

MULATIVE

RESP

ONSES

TIME

| REINFORCERS

RESPONSES

Continuous Reinforcement


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Time

Number of

Responses

(Cumulative

Responses)

Comparing Continuous and Intermittent Reinforcement


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CUMULATIVE

RESPONSES

TIME

Post-Reinforcement

Pause

Run Rate

Fixed Ratio Reinforcement


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CUMULATIVE

RESPONSES

TIME

Variable Ratio Reinforcement


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CUMULATIVERE

SPONSES

TIME

Fixed Interval Reinforcement


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CUMULATIVERESPONSES

TIME

Variable Interval Reinforcement


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CUMULATIVE

RESPONSES

TIME

FIXED RATIO (FR)

SCHEDULE

(e.g., Piece Rate, FixedCommission)

CUMULATIVE

RESPONSE

S

VARIABLE RATIO (VR)

SCHEDULE

(e.g.Telemarket Sales,Slot Machines)

Intermittent (Partial) Reinforcement Schedules

CUMULATIVE

RESPONSE

S

CUMULATIVE

RESPONSE

S

VARIABLE INTERVAL (VI)

SCHEDULE

(e.g., Management byWalking Around, Spot

Bonuses)

FIXED INTERVAL (FI)

SCHEDULE

(e.g., Asking for a Raise,Studying for Exams)

TIME

TIME TIME


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Other Rate-Related Intermittent Schedules

Differential Reinforcement of Alternative (DRA) Responding

Differential Reinforcement of Incompatible (DRI) Responding Differential Reinforcement of Zero (DRO) Responding

Differential Reinforcement of Low Rate (DRL): Reinforce animal

for responding at a slow rate (e.g., press the bar every five seconds).

Used to help people slow down (e.g., hyperactivity). Differential Reinforcement of High Rate (DRH): Reinforce animal

for responding at a fast rate (e.g., press bar five times during every

10-second interval). Used to help people speed up (e.g., dawdlers).

Stretching the Ratio: Start the animal out on a low ratio schedule

(e.g., FR-1) then gradually increase the ratio (FR-3, FR-5, FR-10).

Stretching too fast or too far (e.g., FR-300) creates Ratio Strain

(responding is disrupted).

Extinction: Schedule of non-reinforcement (FR-infinity).


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Other Time-Related Intermittent Schedules

Fixed Time (FT): Reinforcer is delivered after a period of timewithout regard to behavior (e.g., FT-10 means the animal gets a

reinforcer after 10 seconds no matter what it happens to be doing).

Used to establish superstitious behavior.

Variable Time (VT): Reinforcers delivered at irregular intervals,

regardless of behavior (e.g., VT-10 means the reinforcer is deliveredevery 10 seconds, on average, sometimes more, sometimes less).

Also may lead to superstitious behavior.

Fixed Duration (FD): Reinforcer is delivered if a behavior occurs

continuously over a period of time (e.g., practice violin for 30consecutive minutes to get an ice cream cone).

Variable Duration (VD): Required period of performance varies

around some average.


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The Partial Reinforcement Effect (PRE)

Resistance to Extinction: Intermittent (partial) reinforcement

schedules, compared to continuous reinforcement schedules, makeanimals reluctant to give up responding when the reinforcers stop.

Hypotheses about PRE: Why does partial reinforcement lead to

resistance to extinction?

Discrimination Hypothesis: It is harder for the animal to

discriminate between an intermittent schedule and extinction than

between continuous reinforcement and extinction (i.e., the animal

cant tell when partial reinforcement ends and extinction begins).

Frustration Hypothesis: There is greater frustration for animals

who switch from continuous reinforcement to extinction than foranimals who switch from partial reinforcement to extinction.

Frustrated animals stop responding sooner.


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REINFORCED

TRIALS

NON-REINFORCED

TRIALS

Acquisition Extinction

Resistance to Extinction

Continuous versus Intermittent Reinforcement


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Numberof

Responses(CumulativeResponses

)


REINFORCED

TIME

NON- REINFORCED TIME

Resistance to Extinction



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Sequential Hypothesis: The sequence of reinforced and

non-reinforced responses becomes a cue for future responding. An

animal performs longer in the absence of reinforcement followingintermittent rewards because non-reinforced trials are cues to keep on

responding.

Response Unit Hypothesis:

The response should not be defined as a single behavior(e.g., bar press or key peck).

The response is whatever complex actions (units of behavior)

lead to a reinforcement (e.g., the response unit for an FR-3

schedule is three bar presses).

The response unit for extinction more closely resembles theresponse unit for partial reinforcement than for continuous

reinforcement.

During extinction, the animal may actually produces fewer

response units after partial reinforcement than after continuousreinforcement.

Hypotheses about PRE (continued)


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REINFORCED

TIME OR TRIALS

NON-

REINFORCED

TIME OR TRIALS


Unit 1Unit 2

Unit 3

Unit 1

Unit 2

Unit 3

Unit 4

Unit 5

Extinction of Response Units


psy211 operant conditioning schedules

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