Lectur8 Discrimination training

Behavior Analysis

Review

Last time we talked about punishment The procedure of providing consequences for a

behavior that make it less likely to occur

Two other procedures for decreasing the frequency of behavior are Extinction Differential reinforcement

If we want to increase the frequency of behavior then reinforcement is the way to go If the behavior does not occur by itself then we can

use prompting, shaping and chaining

Review

All the procedures we have discussed so far are concerned with increasing or decreasing the frequency of behavior Which is appropriate since solving behavior problems

usually requires changing the frequency of behavior

But sometimes the problem isn't as simple as that Sometimes the problem isn't that the behavior is occurring

too much or too little

Sometimes the problem is that the rate of behavior is too high in one situation and too low in another situation

Review

In these cases we must increase the rate of behavior in the situation in which the rate is too low

And decrease the frequency of behavior in those situations where the rate is too high For example, when we learn to drive we learn to use two

pedals, the accelerator and the break. But driving does not involve just pressing both pedals more

often Slamming the accelerator to the floor when in traffic could be

fatal! Learning to drive a car means learning to perform certain

acts under certain circumstances, and learning to avoid doing those acts in other circumstances

Stimulus discrimination

The tendency for behavior to occur in one situation, but not in another, is called stimulus discrimination

Stimulus discrimination: the tendency for behavior to have different frequencies in different situations

Discriminating between two situations requires that the situations differ in some detectable way E.g. students dress more formally for a job interview than they

do for my class This is because they can discriminate between the two situations. They can do this because there are detectable differences

between the two situations Meeting in a classroom versus an office Being surrounded by class mate versus being one on one with

an interviewer

Discriminative stimuli

There are probably many more differences between the two situations which allow us to discriminate between them

These differences are called Discriminative stimuli

Discriminative stimulus: any event in the presence of which a target behavior is likely to have

consequences that affect its frequencyFor example, waiting outside an interview room,

instead of being sat in a classroom would be a discriminative stimulus

Discriminative stimuli

Since the consequences associated with a discriminative stimulus can be those that either strengthen or weaken a behavior, it follows that there are two types of discriminate stimulus

SD : an event in the presence of which the target behavior is reinforced

(pronounced ess-dee)

SΔ : an event in the presence of which the target behavior is not reinforced

(pronounced ess-delta, the little triangle is the greek letter delta, which actually means the letter D)

Discriminative stimuli

So both kinds of discriminative stimuli have been designated the letter D, for discriminative.

Why have 2 different letters been used? So that we can discriminate between them! If we used

the same symbol for both kinds, we wouldn’t know what sort of consequences the behavior would have

So the letters D and Δ are discriminative stimuliIts is sometimes said that discriminative stimuli signal

the availability of reinforcement An SD indicates a high probability of a target behavior

being reinforced, whilst an SΔ indicates a low probability of of reinforcement of behavior

Example

Imagine the target behavior of Billy is crying in order to get food.

Now Billy's past history of reinforcement has led him to learn that whenever he cries whilst in the presence of his parents, his parents will give him food In this situation, his parents serve as an SD

Now imagine that one day Billy is at his Aunt’s house. In the past his Aunt does not feed him every time he cries. The target behavior has not been reinforced. In this situation his Aunt serves as an SΔ

Example

Remember the definitionsSD : an event in the presence of which the

target behavior is reinforced In our example, when Billy was in the presence of

his parents (the event) his behavior of crying was reinforced

SΔ : an event in the presence of which the target behavior is not reinforced In our example, when Billy was in the presence of

his Aunt (the event) his behavior was not reinforced

Ess-dee’s and Ess-delta’s

Discriminative stimuli are antecedent events that are correlated with certain kinds of consequences SD ‘s are correlated with reinforcement SΔ’s are correlated with extinction or punishment

The functional relations between these antecedents, the behavior and the consequences make explaining behavior easier

All sorts of things can serve as discriminative stimuli A parent saying ‘dada’ is an SD for the baby to say ‘dada’ The symbol 8 is an SD for saying ‘eight’ The positions of the hands on a clock can be an SD for eating,

going to class, leaving work or going to bed!

Discrimination training

Sometimes people don’t respond appropriately to discriminative stimuli For example, Billy might see his Aunty and cry

Theses are called discrimination failures If Billy has not had enough training in discriminating

that his Aunty serves as an SΔ then he wont know that crying does not work

In these situation it is likely that whether a person discriminates appropriately has to do with the training they have received

Discrimination training

Discrimination training is a set of procedures for establishing discriminations

Discrimination training: any procedure that results in a target behavior having different frequencies in

different situationsThis training usually involves reinforcing a behavior

in the presence of the SD and not reinforcing in the presence of the SΔ

There are three ways of doing this Simultaneous discrimination training Successive discrimination training Errorless discrimination training

Simultaneous discrimination training

With this training, people are presented with a choice. For example we might present people with an apple and a banana, and say ‘point to the

apple’ Then if they do point to the apple they get reinforced If they make the wrong choice then they are ignored or mildly punished, such as ‘no

that’s wrong’.

He the apple is the SD and the banana is the SΔ

Now the procedure I just described constitutes one training trial Following this we would remove the apple and banana, re-place

them, and complete the trial again It is important in these trials to vary the position of the fruit as we want to reinforce the

behavior of pointing to the apple, and not pointing left. If we don’t vary the position then the child will not have learned to discriminate between

the apple and the banana, he would have simply learned to point to the object on the left

Although this training could be done with more than 2 items, simultaneous discrimination training always involves items presented at the same time

Successive discrimination training

In successive discrimination training the discriminative stimuli are presented one after the other For example, we would hold the two fruits behind a screen. Then we would present the apple and ask ‘what's this? After the child answers we would provide the appropriate

consequence Then we would put the apply back behind the screen and repeat

the process either with the apple or the banana

If the child does not know the answer then you may have to prompt the answer in the early stages

The successive procedure is a more difficult task than the simultaneous one, since the alternative item is not available for comparison.

Errorless discrimination training

In simultaneous and successive procedures, the person will inevitably make a number of errors. These mistakes include failing to perform the target behavior

in the presence of the SD

And performing the target behavior in the presence of the SΔ

For example, in training people to discriminate between a ball and a table, we would want them to say ‘table’ when shown a picture of a table (SD). However on some trials it is likely that some people would say

‘ball’ when shown a picture of a table (SD) Or they would say ‘table’ when shown a picture of the ball (SΔ)

Errorless discrimination training

Such errors are common during discrimination trainingHowever errors are thought to be problematic, partly

because they can arouse emotional reactions that can interfere with learning

Herbert Terrace developed a procedure for establishing discriminations essentially without errors

It is essentially a variation of simultaneous training The SD is presented in its usual format and appropriate behavior

is reinforced The SΔ however is presented in a very weak form, so that it

evokes no reaction at all For example, when asking people to name the table, we would

show table, and then we would show a faded picture of a ball Gradually the strength of the SΔ is increased

Case study

Some people are great at picking up non verbal cues in social interactions Eg. Knowing that a smile means pleasure, or frown means

displeasure Others are quite bad Azrin and Hayes (1984) decided to give discrimination training

to those who struggled with interpreting non verbal cues They asked male participants to watch a 1 minute video of a

man and woman interacting, and then asked them to rate the woman's degree of interest.

The women on the tapes also rated their interest The idea was that if the woman rated her interest as 2, and the

man rated her interest as a 7, then the man was mis-reading signals

Case study

After this pretesting stage, the male students began training.

The training was similar to the video, except they now received feedback.

This procedure was repeated until the the students had completed 24 trials

The researchers then took a post training measure

The researchers found that men gradually got better at discriminating non verbal cues.

Rules for Discrimination training

Define the target behaviorSelect appropriate discriminative stimuli and

their consequencesPresent the SD and the SΔ with appropriate

consequencesMonitor results

Define the target behavior

By now you know the importance of defining the target behavior

In discrimination training, defining the target behavior means deciding what you want the person to do in the presence of the SD, but not in the presence of the SΔ

Select appropriate discriminative stimuli and their consequences

To do discrimination training you have to identify two or more situations that can be discriminated in some way.

The differences that allow discrimination are the SD and the SΔ

In the initial stages of training it is important that the SD and SΔ are sharply different in some way, so that the person being trained is almost certain to be successful

Because failing is punishing and may make someone less likely to try again. Additionally, you can reinforce a behavior until it occurs

As an example, when teaching kids fruit, we would start with two very different fruit and then move on to more similar items

Present the SD and the SΔ with appropriate consequences

In other words, when showing a child a picture of an apple (SD) and the child says apple (target behavior) then the consequence is ‘well done, good Billy!’

If you show a child a picture of a banana (SΔ) and they answer with the word apple (target behavior) then the consequence is ‘no, that’s not right’

When working with younger or mentally retarded people it is probably best to start with simultaneous procedure.

With older people you can start with successive training. And moving from one procedure to another is always an

option One thing you have to be careful about is the use of

punishment, it may be best to simply ignore the incorrect answers and reinforce the correct answers

Monitor results

As always you must monitor the results so that you can tell how well the training procedure is going.

Its usually helpful to tally the successes and plot them on a graph

Stimulus control

When a satisfactory level of discrimination has been achieved, we say the behavior is under stimulus control

Stimulus control: the tendency for the target behavior to occur in the presence of the SD, but not in the

presence of the SΔ

Stimulus control basically means that a desired level of discrimination has been achieved

In APA stimulus control refers to the tendency for a particular behavior to occur in situations where it is appropriate and not in situations where it is inappropriate E.g. if you are a good driver then you will discriminate between red

lights and green lights!

Stimulus control

Stimulus control is a routine and important part of our lives

However, naturally occurring discrimination training sometime results in inappropriate stimulus control

In fact many behavior problems involve inappropriate stimulus control For example, sometimes a student is an angel in one

class in a devil in another class. But if the one teacher has reinforced good behavior and the other teacher has not, then the teachers become a discriminative stimulus for appropriate behavior

Flash card!

Stimulus discrimination the tendency for behavior to have different frequencies in different

situations Discriminative stimulus

any event in the presence of which a target behavior is likely to have consequences that affect its frequency

SD an event in the presence of which the target behavior is reinforced

SA an event in the presence of which the target behavior is not reinforced

Discrimination training any procedure that results in a target behavior having different

frequencies in different situations Stimulus control

the tendency for a target behavior to occur in the presence of the SD, but not in the presence of the SA