Stimulus Control and Language

Why is Understanding Stimulus Control so Important in Teaching Children with Autism?

“Because the aim of virtually all instruction is to get specific responses to occur reliably under particular antecedent stimulus conditions, all instructional techniques involve manipulations of antecedent stimuli, along with manipulations of consequent stimuli” (Green, 2001, p. 74)

Why is Understanding Stimulus Control so Important in Teaching Children with Autism?

Spradlin and Brady (1999) conceptualized the impairments in language and social skills in children with autism…

as limitations in the development of stimulus control

Social Skill Deficiencies

Appear very early in life as young as several months old

By 1-year old many showed Less eye contact Imitate less Less likely to point out objects to others Failed to engage in reciprocal games such

as pat-a-cake and peek-a-boo Less symbolic or make beileve play Less likely to recognize social emotional

responses in other people

Communication Skill Deficits

Less likely to demonstrate multiple nonverbal

communicative behavior such as joint attention

Response to names & verbal directions

More likely to request than label

Spradlin and Brady (1999)

Proper stimulus control may not develop in children with autism because social stimuli do not function as reinforcers It has been suggested that the patterns of the human face

and physical contact serve as primary reinforcers for typically developing infants

Some children with autism avoid such contact Do faces and hugging not serve as reinforcers from infancy?

• What impact would this have on the development of other reinforcers? Social interactions? Language?

Proper stimulus control may not develop because children with autism require more consistent relationships between antecedents, responses, and consequences…

Classical Conditioning Limitations

Infants developed conditioned responses by pairing various social stimuli with stimuli that elicited the rooting response. E.g., mother’s voice or even footstep

Perhaps children with autism fail to develop such conditioned responses

The natural world is inconsistent in its pairing of social stimulus with unconditioned stimuli

Perhaps children with autism require more consistent pairings than other infants for conditioning to occur or may be more likely to be conditioned to nonsocial aspects of their physical environment.

Limitations in Learning Simple Discrimination

Perhaps children with autism require that a higher percentage of responses in the presence of a stimulus be followed by the same consequence, if they are to come under the control of that stimulus.

Might explain why children with autism prefer playing with objects than peopleContingencies of physical world may be more

reliable that the contingencies of the social world.• E.g., child gestures to parent may or may not be picked

up. Child reaches out for object, always results in obtaining object

Limitations in Learning Simple Discrimination

OverselectivityLovaas found that children with autism often learn to

respond to some of the stimulus but not to all of the stimulus of a complex stimulus

Sunberg & Partington (Cond Disc)Truck in the presence of a truck and the spoken word

truckTypically developing child may respond “truck “ in the

presence of just a truck after a few pairings, a child with autism may learn to only response “truck” in the presence of the spoken word

Limitations in Learning Simple Conditional Discrimination

Most conventional stimulus control is conditional In the presence of discriminative stimulus a specific

response will be reinforced only when conditional stimuli are present. Typically developing children master this easily and their

behavior is reinforced for a high percentage of response they make in the presence of such discriminative stimuli

Children with autism fail to make that conditional discrimination and may ultimately extinguish all responses to the discriminative stimuli

• Social behavior: saying “come play with me” in the presence of Mom who is not otherwise engaged. Child with autism my try to initiate play all at the wrong times and eventually stop trying. Or initiate greetings all at the wrong times.

Response:

Reach up

Reinforcer:Being held

by Mom

SD:

Mom

Social World

Social contingencies are often inconsistent

But mom may not always hold you when you reach up

And the way mom looks, smells, sounds, feels, and holds you may be different

Response:

Reach out

Reinforcer: Feel object in

hand

SD:

Object

Non-social World

• Contingencies in the nonsocial physical world may be more consistent and reliable

• So may be more easily learned by children with autism• Might explain why children with autism prefer playing with objects over people

Getting to hold the object is consistent and the object is consistently the same

Limitations in Stimulus Class Acquisition

Written spoken picture Word word of actual dog DOG DOG a dog

Stimuli are linked by shared function not necessarily physical properties

Children with autism are limited in their development of stimulus classes consisting of members without defining physical properties Leads to substantial limitations in language development

• Can imitate speech but that speech might have no relation to the objects and events that are typically related to that speech

• Or read but not understand what he is reading

Limitations in the Recombination of

Minimal Stimulus-Response Units Much of our behavior involves responding appropriately to

relatively novel situations Generalized imitation Little similarity between what a child sees and the specific

stimulus produced by the imitator's own behavior Perhaps the development of generalized imitation occurs as the

development of instruction following behavior Multiple exemplar training results in learning a number of minimal

stimulus response units when than may be recombined within the imitator is presented a novel combination of responses for imitation

• Children with autism tend to imitate objects easier than people• Leads to substantial social skill deficit

Limitations in the Recombination of

Minimal Stimulus-Response Units Much of our behavior involves responding appropriately to

relatively novel situations Following a verbal instruction By 2, most children can follow 3-word directions Made on the basis of conditional discriminations Children who can recombine units will be more effective

because they have the appropriate word-object and word-action equivalences.

• Recombinations of conditional discriminations and equivalences classes may be limited in children with autism

• Child can complete complex chains of behavior if the chains were invariant but would fail to perform a series of responses on the basis of a novel instruction.

Use of Operant Teaching Methods

Of course we can teach children with autism by establishing stimulus control by structuring consistent relations between specified stimuli behavior and consequences

Procedures to Overcome Basic Reinforcers Problems

Classical conditioning and building motivational systems

Basic Discrimination Training Procedures

Establishing attending skills and eye contact through prompting and reinforcement

What type of prompts??

Establishing New Forms of Conditional Stimulus Control

Imitation Direction following

Establishing New Forms of Conditional Stimulus Control

Identity matching (single mode) Visual: visualAuditory: auditory

Arbitrary matching (multimodal)Visual: auditoryAuditory: visual

Teaching Recombination of Stimulus-Response Units

Teach direction following to promote recombination'sGive me, go get, put onPlane, paper, coatTest for generalization of any give me,

go get, and put on instruction

Concept Formation

Complex stimulus control that results in:Generalization within a class of stimuli

andDiscrimination between classes of

stimuli

Stimulus Class (Cooper et al., 2007)

AKA Concept Set of stimuli that occasion a common

response

These would probably be in the same stimulus class for most people

Types of Stimulus Classes (Fields & Reeve, 2000) Perceptual Class

Stimuli in the set share some physical characteristics Examples: dogs, flowers, children, chairs, cars, etc.

Relational Class Stimuli in the set characterize some abstract

relationship Example: examples of “bigger than,” “same/different”

Equivalence Class Stimuli do NOT share any physical characteristics

(Stimuli “go together” just because society says so) Example: numeral 1 = written one = spoken “WUN”Fields, L., & Reeve, K. F. (2000). Synthesizing equivalence classes and natural categories from perceptual and

relational classes. In J. C. Leslie, & D. Blackman (Eds.). Experimental and applied analysis of human behavior (pp. 59-84). Reno, NV: Context Press.

Equivalence Classes: Definition a finite group of physically disparate stimuli (no perceptual

similarity) stimuli become related solely as a function of teaching (Fields,

Adams, Buffington, Yang, & Verhave, 1996; Fields, Reeve, Adams, Brown, & Verhave, 1991; Sidman & Tailby, 1982; Sidman, 1994)

Emergence of accurate responding to untrained and nonreinforced stimulus-stimulus relations Following the reinforcement of responses to some

stimulus-stimulus relations An equivalence class must contain at least three stimuli (but

often has many more)

Example Stimuli in a 3-Member Equivalence Class

Written word

Spoken word

A picture

DOG“DOG”

Another Example

Written word

Spoken word

A picture

CAT

“CAT”

Stimulus Equivalence

Train:

Emergent Relations:Symmetry: B A and CBTransitivity: A CEquivalence: C A

DOG “dog”

A B C

Teaching & Testing Summary

We TAUGHT 2 conditional relations: A B B C

We TESTED for 4 EMERGENT (DERIVED) relations: B A symmetry C B symmetry A C transitivity C A equivalence

(Another set of tests for REFLEXIVITY (IDENTITY) is often omitted if the learner already has this skill in her repertoire: A A; B B; C C )

Equivalence Class Training & Testing Procedures

Usually taught and tested with arbitrary match-to-sample (MTS)

Symbolic notation is used to outline training/testing procedures: A, B, C, …N represent each of the disparate

stimuli that will make up the class 1, 2, 3, etc. notate the number of classes to

be established Thus, A1 = first stimulus in class 1; B3 =

second stimulus in class 3; etc.

Training & Testing Procedures

To establish equivalence classes, at least two potential classes must be trained concurrently

training establishes both substitutability of all stimuli within a particular equivalence class in addition to discrimination between classes

Training & Testing Procedures

To establish equivalence classes with three members, at least two stimulus-stimulus relations must be trained for each potential class

Let’s consider our DOG and CAT potential equivalence classes

First train the AB relation (given stimulus A select stimulus B) the word DOG (A1) is presented as a sample The positive comparison (Co+) would be the spoken

word dog (B1) (Selection would result in positive feedback or reinforcement)

the negative comparison (Co-) would be the spoken word cat (B2) (Selection would result in corrective feedback or no reinforcement)

DOG

DOGCAT

Training AB relation

A1

B2 B1

Training & Testing Procedures

To train the AB relation word CAT (A2) is presented as a sample

positive comparison (Co+) would be the spoken word cat (B2) (Selection would result in positive feedback or reinforcement)

negative comparison (Co-) would be the spoken word dog (B2) (Selection would result in corrective feedback or extinction)

Training AB relation

CAT

DOGCAT

A2

B2 B1

Training & Testing Procedures

Once responding is 100% correct, we can conclude AB conditional relation has been learned

At this point we can either continue training more conditional discriminations or we can do our first test for an EMERGENT (DERIVED) RELATION (a conditional discrimination that emerges with no direct training history)

If the learner “knows” that A goes with B, can they demonstrate the reverse? (B goes with A)

This emergent relation shows SYMMETRY

TESTING BA symmetry relation

CAT

CAT B2

A2 A1

DOG

TESTING BA symmetry relation

CAT

DOG B1

A2 A1

DOG

Training & Testing Procedures

the BA conditional relation is called “symmetry” because the relation is a mirror image or reversal of the one directly trained (i.e., A=B then B=A)

At this point, we can continue training another conditional discrimination

Let’s train the BC conditional relation

Training BC relation

DOG B1

C2 C1

Training BC relation

CAT B2

C2 C1

Training & Testing Procedures

Once the BC conditional relation is learned, we can do our 2nd test for an EMERGENT (DERIVED) RELATION

If the learner “knows” that B goes with C, can they demonstrate the reverse? (C goes with B)

This emergent relation would show a SECOND SYMMETRY relation

TESTING CB symmetry relation

DOG

C1

B1 B2

CAT

TESTING CB symmetry relation

DOG

C2

B1 B2

CAT

Training & Testing Procedures

If CB symmetry TEST responding is 100% correct, we can continue testing for another EMERGENT (DERIVED) RELATION

If the learner “knows” that A goes with B, and B goes with C, can they demonstrate that A goes with C?

This emergent relation would show a TRANSITIVE relation

TESTING AC transitive relation

A1

C2 C1

DOG

TESTING AC transitive relation

A2

C2 C1

CAT

Training & Testing Procedures

If the AC transitive TEST responding is 100% correct, we have one last test for another EMERGENT (DERIVED) RELATION

If the learner “knows” that A goes with B, and B goes with C, can they demonstrate that C goes with A?

This emergent relation would shows a combination of symmetry and transitivity; it is called an EQUIVALENCE relation

TESTING CA equivalence relation

A1A2

C1

CAT DOG

TESTING CA equivalence relation

A1A2

C2

CAT DOG

Teaching & Testing Summary

We TAUGHT 2 conditional relations: A B B C

We TESTED for 4 EMERGENT (DERIVED) relations: B A symmetry C B symmetry A C transitivity C A equivalence

(Another set of tests for REFLEXIVITY (IDENTITY) is often omitted if the learner already has this skill in her repertoire: A A; B B; C C )

Teaching Stimulus Classes

We need to do a better job at this: Teach:

picture object spoken word Test spoken word sets the occasion for the

picture to ensure an equivalence class has been established

Children with Autism Have Difficulty Learning Concepts (Reeve et al., 2007)

May be due to failure to respond to a wide range of stimuli

If a child only learns “dog” in the presence of 2 dogs, then he might not learn the accurate concept dog – why?

May be due to failure to respond to multiple components of stimuli

If a child only attends to four legs as a feature of “dog”, then he will not learn the accurate concept dog – why?

Overselectivity Children with autism often respond to some parts, but not all

parts, of a complex stimulus Lovaas, Schreibman, Koegel, and Rehm (1971)

When parts of the stimulus were then presented alone… Typically developing children responded to the complex

stimulus and single stimuli similarly Children with autism responded primarily to only one of

the stimuli (it differed across children which one)

Reinforcer: candy

Response:

Press lever

Limitations in Equivalence Class Acquisition

How would this affect language development?Child may be able to imitate speech, but it might

have no relation to the objects and events typically related to it

• Relationship between “dog” and “dog”, but no relationship between “dog” and

Or read but not understand what he is reading• Relationship between DOG and “dog”, but no relationship

between DOG and

Jackson, Williams, and Biesbrouck (2006)

In general, studies show that people with basic language abilities demonstrate equivalence relations and those that don’t do not

It is not known if Language is necessary for the formation of

equivalence classes OR The formation of equivalence classes plays a role

in the development of language

So, How Should We Teach?

There are different ways to present stimuli, but research suggests that…

Simultaneous Discrimination arrangement produces faster discrimination and generalization

Simultaneous Discrimination Arrangement• SD and SΔ are presented together at same time

Successive Discrimination Arrangement• SD and SΔ are presented separately

Green (2001)

Present the comparisons in an array on a board (Velcro!) Begin each trial with having the learner make an observing

response (look at teacher or point to sample) Teach the learner to point rather than “put with same” Have at least 3 comparisons on every trial Present the samples unsystematically. A good rule of thumb

is don’t present the same sample more than 2x in a row. Limit the auditory stimulus to the target word (i.e., don’t say

“touch”, “point to”)

Green (2001)

Present each sample equally often. All comparisons should be in the field during every trial. Each comparison should be the correct answer for only 1 sample. Each comparison should be the incorrect answer equally often. The number of comparisons in the field should equal the number of

samples presented in a block of trials. Within a session of trials, a different sample should be presented on

each trial, but the same comparisons should appear on every trial. Each comparison should be the correct response for only one sample,

and should be the incorrect response equally often. The position of the correct comparison should vary from trial to trial. Between trials, rearrange the comparison stimuli out of sight Use errorless teaching methods (most-to-least prompting and prompt fading)

Green (2001)

References Chavez-Brown, M., Scott, J., & Ross, D. (2005). Antecedent selection: Comparing simplified

and typical verbal antecedents for children with autism. Journal of Behavioral Education, 14, 153-165.

Cooper, J. O., Heron, T. E., & Heward, W. L. (2007). Applied behavior analysis. Upper Saddle River, NJ: Pearson Prentice Hall.

Fields, L., & Reeve, K. F. (2000). Synthesizing equivalence classes and natural categories from perceptual and relational classes. In J. C. Leslie, & D. Blackman (Eds.). Experimental and applied analysis of human behavior (pp. 59-84). Reno, NV: Context Press.

Green, G. (2001). Behavior analytic instruction for learners with autism: Advances in stimulus control technology. Focus on Autism and Other Developmental Disabilities, 16, 72-85.

Laraway, S. Snycerski, S., Michael, J., & Poling, A. (2003). Motivating operations and terms to describe them: Some further refinements. Journal of Applied Behavior Analysis, 36, 407-414.

Lovaas, O. I., Schreibman, L., Koegel, R., & Rehm, R. (1971). Selective responding by autistic children to multiple sensory input. Journal of Abnormal Psychology, 77, 211-222.

Reeve, K. F., Reeve, S. A., & Brown, J. L. (2007, August). Concept formation in children with autism: What do we know about it? Paper presented at 3rd annual conference of the New Jersey Association for Behavior Analysis, Rutgers University.

Spradlin, J. E., & Brady, N. C. (1999). Early childhood autism and stimulus control. In P. M. Ghezzi, W. L. Williams, & J. E. Carr (Eds.), Autism: Behavior analytic perspectives (pp. 49-65). Reno, NV: Context Press.