Instrumental Conditioning II

S R

What is learned?

Thorndike:Reinforcement “stamps in” this connection

S R

What is learned?

Edwin Guthrie: Contiguity theory, reinforcement doesn’t do much of anything (directly)

S R

O

What is learned?

?

S R O

2-Process Theory

operant

Pavlovian

S R

CR

2-Process Theory

operant

Pavlovian

Evidence for 2-process theoryPavlovian-Instrumental Transfer

Phase 1 Phase 2 Test

LeverO LightO Light: Lever?No CS: Lever?

# Presses

Light No CS

S R O?

?

What is learned?

SO

Trapold

Phase 1 Phase 2 Test

R LeverPellet TonePellet Tone:Left? Right?

L LeverSucrose LightSucrose Light:Left? Right?

# Presses

Light Noise

Left

Right

ROColwill & Rescorla (1986)

Phase 1 Devaluation Test

Push LeftPellet Pellet+LiCl Right?

Push RightSucrose Sucrose+LiCl Left?

What is a reinforcer?

Operational Definition (behaviorists): That which increases the probability of the response that preceded it.

Thorndike: A stimulus that produces a “satisfying state of affairs”

Can we be more precise?

The Drive-Reduction hypothesis

Servomechanism: device that maintains a controlled variable within a set range

Drive Reduction Theory

Amt of H2O in body

Set Point

Seek water/ don’t seek water

drives

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.