Schedules of Reinforcement CH 17,18,19. Divers of Nassau Diving for coins Success does not follow...
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Transcript of Schedules of Reinforcement CH 17,18,19. Divers of Nassau Diving for coins Success does not follow...
Schedules of Reinforcement
CH 17,18,19
Divers of Nassau
• Diving for coins
• Success does not follow every attempt
• Success means reinforcement
Intermittent Reinforcement
• A reinforcer follows the response only once in a while.
Continuous Reinforcement (CRF)
• A reinforcer follows every response.
• Best used for shaping or maintaining difficult behavior.
Shaping with Reinforcement
Before:
Andrew has no gum
Behavior Initial: NA
Intermed: Moves lips only
Terminal: Says words unclearly
Behavior Initial: Andrew moves lips
Intermed: Andrew makes croaking sound
Terminal: Says words clearly
After:
Andrew receives no gum
After:
Andrew receives gum
Reinforcement
Extinction
Schedule of Reinforcement
• The way reinforcement occurs because of the number of responses, time between responses, and stimulus conditions.
Schedules of Reinforcement
• Ratio– Fixed Ratio (FR)– Variable Ratio (VR)
• Interval– Fixed Interval (FI)– Variable Interval (VI)
Fixed Ratio (FR) Schedule of Reinforcement
• A reinforcer follows a fixed number of responses.
FR Responding
• After a response is reinforced, no responding occurs for a period of time, then responding occurs at a high, steady rate until the next reinforcer is delivered.
Pauses
Reinforcers Reinforcement always immediately follows the 5th response!!!!
This is an FR5 schedule of reinforcement.
Postreinforcement Pause (PRP)
• The name for the pause after the consumption of the reinforcer and before the next ratio of responses begins.
FR & PRP
• Length of the pause is proportional to the size of the ratio.
• Small ratio – pausing is short
• Large ratio – pausing is long
General Rule for establishing intermittently reinforced
behavior:First use CRF and gradually increase the intermittency of reinforcement as responding
stabilizes at a high rate.
FR120
• What are the response requirements?
• When will reinforcement be delivered?
• What will the pattern of responding look like?
Cumulative Graph for FR
0
20
40
60
80
100
120
140
Time
Cum
ulat
ive
Num
ber
of R
espo
nses
Reinforcers
Post reinforcement pauses
Variable Ratio (VR) Schedule
• A reinforcer follows after a variable number of responses
VR Responding
• VR schedules produce a high, constant rate of responding, with almost no postreinforcement pausing.
0
20
40
60
80
100
120
140
160
180
Time
Cum
ulat
ive N
umbe
r of R
espo
nses
VR 50
VR 50
• Schedule notation
• Number designates the average number of responses required for reinforcement
How do typical schedules of reinforcement differ from
gambling?
• See pages 290-291
Skinner Box vs. 1 Armed Bandit
Typical VR Gambling Schedule
Many interspersed learned reinforcers
No Yes
Amount of reinforcer varies from ratio to ratio
No Yes
Small ratio No Yes
Emotional reinforcers No Yes
Time Dependent Schedules
• Fixed Interval (FI)
• Variable Interval (VI)
FI Schedule of Reinforcement
• A reinforcer is contingent on the first response after a fixed interval of time since the last opportunity for reinforcement.
Fixed Interval 10s Schedule of Reinforcement
0
50
100
150
200
0 10 20
Seconds
Cum
ulat
ive
Num
ber
of
Res
pons
es
Reinforcer
Fixed Interval 200-s Schedule of Reinforcement
0
20
40
60
80
100
120
140
160
180
200
Seconds
Cu
mu
lati
ve N
um
ber
of
Resp
on
ses
Reinforcer
Example: Fixed Interval (FI) Schedule of Reinforcement
FI 200-s
200 seconds
400 seconds
600 seconds
Fixed-Interval Scallop
• A FI schedule often produces a scallop – a gradual increase in the rate of responding with responding occurring at a high rate just before reinforcement is available. No responding occurs for some time after reinforcement (Post Reinforcement Pause.
Fixed Interval 200-s Schedule of Reinforcement
0
20
40
60
80
100
120
140
160
180
200
Seconds
Cu
mu
lati
ve N
um
ber
of
Resp
on
ses
Reinforcer
Example: Fixed Interval (FI) Schedule of Reinforcement
FI 200-s
200 seconds
400 seconds
600 seconds
Scallop
PRP
Fixed Interval 200 s
0
0.1
0.2
0.3
20 40 60 80 100 120 140 160 180 200
Time (sec)
Rel
ativ
e F
requ
ency
+/+
+/rl
rl/rl
A
Lever Pressing of Mice after Training
Term paper vs. FI
• Term paper does not have a deadline.
FI vs. Term Paper
FI Term PaperDoes early responding effect anything?
No Yes
Do you get more if you work harder?
No Yes
Is the relevant response class clear?
Yes No
Are there calendars and clocks?
No Yes
Is there a deadline? No YesIs the reinforcer too delayed?
No Yes
Fixed Time & Superstitious Behavior
• Fixed time schedules of reinforcement– A reinforcer is delivered after the passage of a
fixed period of time, independently of the response.
• Superstitious behavior– Behaving as if the response causes some
specific outcome when it really does not.
Superstitious behavior of the pigeon:
Experiment by SkinnerFixed Time Schedule
Variable Interval (VI) Schedule of Reinforcement
• A reinforcer is contingent on the first response after a variable interval of time since the last opportunity for reinforcement.
VI Responding
• VI schedules produce a moderate rate of responding with almost no postreinforcement pausing.
Comparing/Contrasting Ratio and Interval Schedules
• Pg. 305: table
• Pg. 305: cumulative records
Continuous vs. Intermittent
• CRF – every response is reinforced
• Intermittent reinforcement – only some responses produce a reinforcer.
Intermittent Reinforcement
• Makes the response more resistant to extinction than does continuous reinforcement.
Resistance to Extinction
• The number of responses or the amount of time before a response extinguishes
Resistant to Extinction and Intermittent Reinforcement
• Intermittent reinforcement makes the response more resistant to extinction than does continuous reinforcement.
• Why? Hard for the rat to tell the difference between only an occasional reinforcement and no reinforcement
• CRF followed by EXT: rats quickly stop responding: easy discrimination between reinforcement & extinction contingencies
4 Types of Concurrent Contingencies
1. Two compatible responses
2. Compatible contingencies for a single response
3. Incompatible contingencies for a single response
4. Two incompatible responses
Concurrent Contingencies
• Contingencies that are available at the same time.
• More than one contingency of reinforcement or punishment is available at the same time.
Concurrent Contingencies
• Two levers in chamber– VI 300 s on Left lever– VI 30 s on Right lever
• Will animal allocate more responses to the left or the right lever?
• Matching Law (pg. 330)% of Left lever presses = % Left-lever reinforcers
Matching Law
• Relative Frequency of responding on two concurrent schedules of reinforcement equals the relative value of reinforcement on those two schedules