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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