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Instrumental Conditioning II
What is learned?
Thorndike:
S
Reinforcement
“stamps in” this
connection
R
What is learned?
Edwin Guthrie: Contiguity theory,
reinforcement doesn’t do much of
anything (directly)
S
R
What is learned?
S
R
O
?
2-Process Theory
operant
S
R
Pavlovian
O
2-Process Theory
operant
S
R
Pavlovian
CR
Evidence for 2-process theory
Pavlovian-Instrumental Transfer
Phase 1
Phase 2
LeverO
LightO
#
Presses
Light
No CS
Test
Light: Lever?
No CS: Lever?
What is learned?
S
R
?
?
O
SO
Trapold
Phase 1
Phase 2
Test
R LeverPellet
TonePellet
Tone:Left? Right?
L LeverSucrose
LightSucrose
Light:Left? Right?
Left
Right
#
Presses
Light
Noise
RO
Colwill & Rescorla (1986)
Phase 1
Push LeftPellet
Devaluation
Pellet+LiCl
Push RightSucrose Sucrose+LiCl
Test
Right?
Left?
What is a reinforcer?
Thorndike: A stimulus that produces a “satisfying state of
affairs”
Operational Definition (behaviorists): That which
increases the probability of the response that preceded it.
Can we be more precise?
The Drive-Reduction hypothesis
Servomechanism: device that maintains a
controlled variable within a set range
Drive Reduction Theory
Set Point
Amt of
H2O in
body
drives
Seek water/
don’t seek
water
Drive Reduction Considered: Are
reinforcers necessary for survival?
– Sensory stimulation is a reinforcer
• Monkeys work for visual access
– Eating to excess
– Drugs of Abuse
– “Pleasure centers” of the brain
Behavioral Regulation View: The
Premack Principle
• Behaviors are reinforcing, not stimuli
• To predict what will be reinforcing, observe
the baseline frequency of different
behaviors
• Highly probable behaviors will reinforce
less probable behaviors
Premack Revised: The Response
Deprivation Hypothesis
• Timberlake & Allison (1974)
• Low frequency behaviors can reinforce high
frequency behaviors
• All behaviors have a preferred frequency
• Deprivation below that frequency is
aversive.

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