The Associative Structure of Instrumental Conditioning Simple, Binary Associations  S-R association

S-R association T BPfood  see more BP during the T than in its absence

The Associative Structure of Instrumental Conditioning Simple, Binary Associations  S-R association  R-O association

R-O association Colwill & Rescorla (1985) Training DevaluationTest R1R1 O1O1 R2R2 O2O2 O1O1 LiCL O2O2 nothing R 1 and R 2

The Associative Structure of Instrumental Conditioning Simple, Binary Associations  S-R association  R-O association  S-O association

S-O association Colwill & Rescorla (1988) S d training Response trainingTest S1S1 R1R1 O1O1 S2S2 R2R2 O2O2 R3R3 O1O1 R4R4 O2O2 S1:S1:R 3 vs R 4 S2:S2:

The Associative Structure of Instrumental Conditioning Simple, Binary Associations  S-R association  R-O association  S-O association Hierarchical Associations  S – [R – O]

Hierarchical Associations Rescorla (1990) Training Test S1S1 [R 1 O1]O1] S1S1 [R 2 O2]O2] S2S2 [R 1 O2]O2] S2S2 [R 2 O1]O1] But also, R1R1 O1O1 R2R2 O2O2 S 1 : R 1 vs R 2 S 2 : R 1 vs R 2

What if we trained: S 1 – [R 1 – O 1 ] S 2 – [R 2 – O 2 ] And then gave: R 1 – O 1 Which S is more informative? Would an increase in responding in the presence of S 2 relative to S 1 be indicative of a hierarchical association?

Theories of Reinforcement 1. Reinforcement as stimulus presentation Thorndike  a stimulus that is satisfying Hull’s Drive Reduction Theory  any stimulus that satisfies the biological need, Restores homeostasis, and thus reduces the drive state serves as a reinforcer 2. Reinforcement as behavior  The Premack Principle  Behavioral Regulation Approaches

Chapter 8 Stimulus Control of Behavior

Stimulus Control  Thorndike's original law of effect implied stimulus control. The stimuli (S +/- ) present at the time of the reinforced response come to control the response. Classical Conditioning:  The CS (CS +/- ) comes to control responding Operant Conditioning:

How do you know that an instrumental response has come under the control of certain stimuli? Reynolds (1961)

Reynolds experiment demonstrated:  Stimulus control the stimulus control of instrumental behavior is demonstrated by variations in responding (differential responding) related to variations in stimuli  Stimulus discrimination an organism is said to exhibit stimulus discrimination if it responds differently to two or more stimuli If an organism does not discriminate between 2 stimuli, its behavior is not under the control of those cues

To measure the perceived similarity of different stimuli from the training stimulus: A Generalization Test: –Measure responding when a CS +/- or an S +/- is replaced with test stimuli which are different from (but usually similar to) the original CS or S. –If the stimulus can be changed across a single dimension (e.g., wavelength of light or frequency of sound), then a generalization gradient can be plotted. Stimulus Generalization and Discrimination

Generalization Gradient  obtained by presenting a number of stimuli of different values from the same dimension (e.g., wavelength/color; frequency/pitch) as the CS +/- or S +/- used in training  Generalization is evident to the degree that responding to test stimuli is similar to responding to the training stimulus (flatter gradient).  Discrimination is evident to the degree that responding to test stimuli is different from responding to the training stimulus (more peaked gradient).

The Effects of Training Procedures on Generalization and Discrimination  Nondifferential Training : –S + always present. Trained to respond (or not) in presence of CS + or S + (or CS - or S - ). Then usually tested in extinction with a variety of test stimuli

Flat gradient Similar to Figure p. 234 in text More generalization

 Differential (or Discrimination) Training: - Presence/Absence Training: * reinforced in presence of S +, not in its absence. The Effects of Training Procedures on Generalization and Discrimination  Nondifferential Training : - S + always present.

Flat gradient More peaked gradient Similar to Figure p. 234 in text More generalization Less generalization; more discrimination

- Intradimensional Training: * reinforced in presence of S + (e.g., tone of 1000 cps) and not reinforced in presence of S - (e.g., tone of 950 cps), S + and S - from the same dimension. The Effects of Training Procedures on Generalization and Discrimination  Nondifferential Training : - S + always present.  Differential (or Discrimination) Training: - Presence/Absence Training: * reinforced in presence of S +, not in its absence.

More peaked gradient Flat gradient Most peaked gradient Similar to Figure p. 234 in text Less generalization; more discrimination Least generalization; most discrimination Non-Differential Presence/Absence Intradimensional

P eak Shift

Spence’s Theory of Discrimination Learning Following Intradimensional Training: For the S + (or CS + ), there is an excitatory generalization gradient around it. That is, S + (or CS + ) elicits the most responding; similar stimuli also elicit responding, with the greater the similarity, the greater the tendency to respond. For the S - (or CS - ) there is an inhibitory gradient around it. The most inhibition is produced by S -, but similar stimuli also inhibit responding. The greater the similarity, the greater the tendency to inhibit responding.

Peak Shift: Explained by Spence’s Theory of Discrimination Learning Peak Shift: –occurs when the peak of responding is shifted away from the original S + in a direction opposite to that of the S -. Spence's theory explains the Peak Shift: –There is an excitatory gradient around S + and an inhibitory gradient around S -. –Observed responding is determined by the sum of the two gradients. –Peak shift occurs because the inhibitory gradient around S - subtracts more from the excitation at S + and between S + and S - than it does from stimuli similar to S + that are further away from S -.