discrimination & complex stimulus control chs12 & 13

Discrimination & Complex Stimulus Control

Chs12 & 13

Reinforcement-Based Discrimination

Before

S

SD

After

After

Behavior

Discriminative Stimulus (SD)

• A stimulus in the presence of which a particular response will be reinforced or punished

S-delta (S)

• A stimulus in the presence of which a particular response will not be reinforced or punished

Reinforcement-Based Discrimination

Before

Chicken has no food

S

Breland

SD

Brelandlesss target

After

Chicken has no food

After

Chicken has food

Behavior

Chicken pulls the trigger

Discrimination Training Procedure

• Reinforcing or punishing a response in the presence of one stimulus and extinguishing it or allowing it to recover in the presence of another stimulus.

Stimulus discrimination(stimulus control)

• The occurrence of a response more frequently in the presence of one stimulus than in the presence of another, usually as a result of a discrimination training procedure

Differential Reinforcement vs. Stimulus Discrimination

One Stimulus Two Stimuli

One Response Class

No differentiation or discrimination

Stimulus discrimination

Two Response Classes

Response differentiation

Combined differentiation & discrimination

Concept training

• Intuition?– Control by a concept or set of contingencies the

person or organism does not define or describe

• Concept of PERSON is complex

Herrnstein & Loveland

• Concept training procedure with nonverbal animal

Concept Training

Before

No grain

Sdelta

Various pictures with no people

SD

Various pictures of people

After

Pigeon has no grain

After

Pigeon has grain

Behavior

Pigeon pecks key

Concept Training

Before

No grain

Sdelta

Various painting by others

SD

Various Picasso paintings

After

Pigeon has no grain

After

Pigeon has grain

Behavior

Pigeon pecks key

Complex Stimulus Control

• Conceptual stimulus control

Stimulus class (concept)

• A set of stimuli all of which have some common physical property

• A stimulus class is the same thing as a concept

Stimulus generalization

• The behavioral contingencies in the presence of one stimulus affects the frequency of the response in the presence of another stimulus

• E.g. – reinforcement for pecking in presence of 1 Picasso painting affects likelihood of pecking in presence of another Picasso painting (more likely)

Concept Training

• Reinforcing or punishing a response in the the presence of one stimulus class and extinguishing it or allowing it to recover in the presence of another stimulus class

Concept training

Vs.

Conceptual stimulus control

Conceptual stimulus control

• Responding occurs more often in the presence of one stimulus class and less often in the presence of another stimulus class because of concept training

Testing for stimulus generalization

• Test for stimulus generalization using novel stimuli

• If respond correctly to novel stimuli, can say the behavior is under the stimulus control of concepts.

Stimulus generalization vs. stimulus discrimination

• Responds in presence of SD but not in the presence of S. This is ______________

• Responds at similar rates in presence of SD and S. This is __________________

Stimulus Generalization

0

10

20

30

40

50

60

Num

ber

of R

espo

nses

red green blue yellow

Stimulus Discrimination

0

5

10

15

20

25

30

35

40

45

Num

ber

of R

espo

nses

red green blue yellow

Stimulus-Generalization Gradient

0

50

100

150

200

250

300

350

Blue Yellow-green

Red

TEST COLORS

Num

ber

of K

ey P

ecks

Generalization vs. Discrimination

• Amount of generalization is the opposite of the amount of stimulus discrimination (stimulus control)

Fading, Errorless Learning, Imitation

Chapter 13 & 14, Part 2

Fading

• Stimulus dimensions– The physical properties of stimuli

Stimulus Dimensions

• Stimuli differ from each other– House vs. car

• Obvious dimensions– Size, weight, shape, material, etc.

vs.

Stimulus Dimensions

• The more dimensions along which objects differ, the easier to establish a discriminative stimulus control

• The fewer dimensions along which objects differ, the harder it is to establish discriminative stimulus control

Example

• Good golf balls (SD) vs. bad golf balls (S)

• This is a discrimination that is difficult

• How can the discrimination be established?

• The 2 golf balls are similar in so many dimensions….and differ in only a few– Roundness, resiliency, hardness of cover

Make stimulus dimensions more salient, then use fading

• Color the bad golf ball green

• Leave the good golf ball alone

• Reinforce picking out good golf balls

• Don’t reinforcer picking bad (green) golf balls

Fading

• Gradually fade out the difference between good balls and bad balls by reducing the “green”

Fading procedure

• At first, the SD and the Sdiffer along at least two stimulus dimensions (green & white, new & old).

• The difference between the SD and the Salong all but one dimension is reduced until there is no difference along the reduced dimensions.

• The the SD and the Sdiffer along only one dimension

Errorless Discrimination Procedure

• The use of a fading procedure to establish a discrimination, with no errors during training.

Jimmy

Susan

Jimmy

Susan

Jimmy

Jimmy

Susan

Susan

Jimmy

Susan

Jimmy

Susan

Jimmy

Reinforcement-Based Discrimination

Before

Jimmy has no raisin

S

Susan on a black card

SD

Jimmy on a white black card

After

Jimmy has no raisin

After

Jimmy has a raisin

Behavior

Jimmy picks card

Stimulus Dimensions

• Lettering

• Shading

• At first, choice of cards was under the control of the dimension of ________

• Then, after fading, responding was under the control of the dimension of _______

Techniques of Gradual Change

Procedure Area of Application

Purpose

Shaping Response differentiation

To bring about a response not made by the organism

Reinforcer Reduction

Type & amount of reinforcer

To maintain responses already made or to establish a particular pattern of responses

Fading Stimulus discrimination

To bring the response under the control of stimuli that didn’t exert control initially

Reinforcer Reduction

• Move from primary to secondary reinforcers

• Change from 3 pellets to 1 pellet

Imitation

• The form of the behavior of the imitator is controlled by similar behavior of the model

Imitation Training: Stimulus Discrimination

Before

Marilla has no food & praise

S

No arm raised or no “do this”

SD

Raised arm and “do this”

After

Marilla has no food & praise

After

Marilla has food & praise

Behavior

Marilla raises arm

Imitation Training: Differential Reinforcement

Before

Marilla has no food & praise

After

Marilla has no food & praise

After

Marilla has food & praise

Behavior

Marilla raises arm

Behavior

Marilla raises arm

Training Imitation

• Train imitation with a partner– Touch nose– Touch toes– Raise hand– Etc……

Generalized Imitation

• Imitation of the response of a model without previous reinforcement of imitation of that specific response.