Lecture 6 - Stimulus Discrimination, Generalization and Shaping

antecedents

stimuli or events that precede operant responses

The effects of behavioural principles

(reinforcement, extinction, punishment) are

______ specific

context, (e.g., depends on the situation)

Stimulus control =

behaviour is more likely to occur when a specific antecedent stimulus was presen

Stimulus class =

specific category of stimulus

Reinforcement

● Behavior is reinforced in specific circumstances (when specific antecedents are present)

● Behavior is more likely to occur in the future in similar circumstances (when similar antecedents are present)

Extinction

● Behavior is no longer reinforced when it occurs in specific circumstances (when specific antecedents are present)

● Behavior stops occurring in the future in similar circumstances

Punishment

● Behavior is punished in specific circumstances (when specific antecedents are present)

● Behavior stops occurring in the future in similar circumstances

A-B-C’s of Operant Behavior

Antecedent (trigger)--> Behavior --> Consequence (detrmine if inc or dec)

● Contingency of reinforcement

● Three-term contingency

A-B-C’s of Operant Behavior examples

Stimulus Discrimination Training

SD = discriminative stimulus:

● The SD is the antecedent stimulus that is present when the behavior is reinforced

SΔ = S-delta

● The SΔ is the antecedent stimulus that is present when the behavior is not reinforced

SD ----> Behavior ----> Reinforcer (SR)

SΔ ----> Behavior ----> Extinction (EXT)

● Outcome: In the future, the behavior is more likely to occur when the SD is present

** Stimulus control = the behavior occurs in the presence of the SD (the outcome of discrimination training)

Stimulus Discrimination Training example

Identify the SD and the S-delta

You feed your dog Spot each time Spot begs when you are at the dinner table. You never feed Spot when he begs and you are not at the dinner table. Now he only begs when you are at the table

sd - dinner table

sdelta - not at dinner table

Identify the SD and the S-delta

When Billy falls at soccer practice and Mom is there, he cries and Mom responds with attention. When Dad is there, he tells Billy to get back on the field. Billy cries when he falls only when Mom is at soccer practice.

sd - mom there

sdelta - dad there

Identify the SD and the S-delta

Martha works in a group home for individuals with disabilities. Her supervisor comes around about once an hour and praises her if he sees her interacting with the clients. Martha interacts with the clients only when she hears her supervisor approach.

sd - interacting when superviser there

sdelta - absent

SD vs EO

● SD – stimulus that is present when a behavior is reinforced

● EO – event that makes a stimulus more potent as a reinforcer

● Both make a behavior more likely (at the time, not in the future)

● Opportunity to get the reinforcer (SD) vs. motivation for the reinforcer (EO)

● Both are necessary to evoke a behavior

Behavior altering effects of stimuli

● Antecedents (EOs and SDs)

○ evoke a behavior

○ alter the current probability of a behavior

○ behavior is more likely in their presence now (behavior altering effect)

is it gunna happen now? like this trial?

repertoire altering effects of stimuli

● Consequences (reinforcers and punishers)

○ strengthen or weaken a behavior

○ alter the future probability of a behavior

○ behavior is more (or less) likely in the future (repertoire altering effects)

Generalization

● Behavior occurs in the presence of stimuli that are similar in some way to the SD

● Because the behavior was reinforced in the presence of the SD, in the future, the behavior also occurs in the presence of similar stimuli.

Generalization gradient:

as stimuli are less and less similar to the SD, the behaviour is less likely to occur in the presence of the stimuli

Generalization example

Generalization vs. Discrimination

• Discrimination

The behavior occurs in the presence of a particular stimulus (the SD)

• Generalization

The behavior occurs in the presence of similar stimuli (similar to the SD)

Behavioral Acquisition Strategies (to learn new behaviours)

● Shaping

● Prompting and transfer of stimulus control

● Chaining

● Behavioral skills training

Defining Shaping

● Differential reinforcement of successive approximations of a target behavior

○ Differential reinforcement – reinforce one behavior and not others

○ Successive approximations – behaviors that are closer and closer to the target behavior

basically the process of renforcing behaviour that is gradually more simmilar to the target behaviour

Shaping process example

dog rolling over

first lay

thens die

then roll over

What two principles are involved in shaping?

Reinforcement and Extinction!

When is Shaping Used?

● 3 therapeutic uses of shaping

● When instructions, modeling, and prompting are not applicable or not effective

● Accidentally to develop problem behaviors

● To develop new topographies of a behavior

● To develop new dimensions of a behavior

● To reinstate old behaviors that are not occurring (walking, Mrs. F refusing to walk after hip replacement surgery)

● 3 therapeutic uses of shaping

○ To develop new topographies of a behavior

○ To develop new dimensions of a behavior

○ To reinstate old behaviors that are not occurring

● To develop new topographies of a behavior

○ Generating a novel behaviour

○ E.g., language development in children

● To develop new dimensions of a behavior

○ Changing some dimension of an existing behaviour

○ E.g. increase bladder control (washroom use time)

Shaping Problem Behaviors: Examples

● Dog begging for food

● Child tantrums or other problem behaviors

Using Shaping steps

1. Define the target behavior

2. Is shaping the preferred procedure?

3. Identify the starting behavior

4. Choose the shaping steps

5. Choose the reinforcer

6. Reinforce each successive approximation

7. Move at the proper pace

2. Is shaping the preferred procedure?

- Use instructions/modeling/prompting if possible

3. Identify the starting behavior

- The person must already exhibit the behavior (they alr can do)

- Choose a behavior you can build on to achieve the target behavior

4. Choose the shaping steps

- Each step is a closer approximation to the target behavior

- Steps are not too big

5. Choose the reinforcer

- Must function as a reinforcer for the individual

- Consider the effects of satiation during shaping (use conditioned

reinforcers)

6. Reinforce each successive approximation

- Reinforce first approximation until it occurs a number of times

- Stop reinforcing first approximation and reinforce next

approximation until it occurs a number of times

- Continue until the target behavior occurs