Stimulus Control

Stimulus Control

Stimulus Control is involved in… • When to talk to strangers • When to cross the street • When to say hi to someone • When to eat week-old food out of the refrigerator • When to say “reward” and when to say “reinforcer” • When to hug vs. give hand shake to someone

Stimulus Control • Stimulus control is everything! • Most children with autism have difficulty emitting social and verbal behavior under appropriate stimulus conditions.

Reinforcer: Break from work SD: Teacher Joe Response: Scream SΔ: Teacher Jenny No break

Reinforcer: Door is opened SD: Teacher Response: “Open door” SΔ: Peer Door is not opened

Reinforcer: “ouch!” SD: Mom in room Response: pinch SΔ: Dad in room No response

Reinforcer: spoon SD: Person in room Response: Hold out picture of spoon SΔ: No one in room No spoon

Stimulus Control • Stimulus Discrimination • Stimulus Generalization

Stimulus Control • Stimulus Discrimination • Definition: Degree to which antecedent stimuli set the occasion for particular responses • precise degree of stimulus control • E.g., Man has beard and is Daddy; Man has beard and is Uncle Eddie • Stimulus discrimination is taught by using discrimination training procedures such as differential reinforcement

Stimulus Control • Stimulus Generalization • Definition: When a response is reinforced in the presence of one stimulus there is a general tendency to respond in the presence of new stimuli that have similar physical properties ore have been associated with the stimulus. • loose degree of stimulus control • E.g., All men with beards are Daddy • Cannot be taught –but can plan for it

Development of Stimulus Control • Stimulus discrimination training • Requires one behavior • Two antecedent stimulus conditions (the SD and the S) • Responses that occur in the presence of the SD are reinforced (thus, the response increases in the presence of the SD) • Responses that occur in the presence of the S are not reinforced (this, the response decreases in the presence of the S • Can also result in a lesser amount or quality of reinforcement

Development of Stimulus Control • Example: Reinforcing a child’s saying “red” when someone asks “What’s your favorite color?” and witholding reinforcement if they said “red” when asked “ What’s your name?”

SD: “What’s your favorite color?” Response: “red” Reinforcer: “Super! You said red!” SΔ: “What’s your name?” No praise

Differential Responding • When a child’s behavior comes under the control of the SD, • We say the SD has acquired stimulus control over the child’s behavior • So the verbal stimulus “What’s your favorite color?” gains stimulus control over the response “red” – why? • And the child is discriminating or responding differentially

Stimulus Generalization • When a response is reinforced in the presence of one stimulus, • That same type of behavior tends to be evoked by stimuli that share similar physical properties with that controlling antecedent stimulus

If you teach “green” usingthis color circle … Stimulus Generalization Student’s most likely to say “green” Student’s less likely to say “green” (discrimination) Student’s less likely to say “green” (discrimination)

Stimulus Generalization • So…when a response has been trained with a specific teacher, materials, or setting • It may occur with other, similar teachers, materials, or settings • The more similar the novel teacher, materials, and setting are to the training teacher, materials, and setting… • The more likely stimulus generalization will occur

Discrimination vs. Generalization • Essentially opposite processes • As one increases, the other decreases • Discrimination • Responding differently to 2 or more stimuli • Tight degree of stimulus control • Generalization • Responding similarly to 2 or more stimuli • Loose degree of stimulus control

Stimulus Discrimination Stimulus Generalization Stimulus Discrimination and Stimulus Generalization are a Continuum

Why Teach Discriminations? • Discrimination is a fundamental process that controls behavior. • Discrimination allows us to differentiate when reinforcement is available for specific responses.

Why Teach Discriminations? • Many essential tasks require discrimination skills • Reading. • Labeling Objects. • Following directions. • Following activity schedules. • Greeting people. • Self-care skills.

Basic Problem of Discrimination Training • Discrimination training teaches learners to perform a specific response in the presence of a specific stimulus and not to perform that response in the presence of other stimuli.

Discrimination Training • Many individuals with developmental disabilities have difficulty learning discriminations • Stimuli are compound (they consist of different elements) • It may be difficult to control which element(s) of the stimulus exert control over behavior • We must be careful how we teach and what stimuli we use!

Stimulus Compounding • All stimuli are compound. • They consist of many different elements. • It is difficult to control which element or elements of the stimulus exert control over behavior. • We need to be careful how we teach and what stimuli we use.

2 Types of Discriminations. • Simple Discriminations. • Non-Conditional Discrimination. • Conditional Discriminations. • Matching-to-sample. • Arbitrary Discrimination.

Simple Discrimination • Stimulus is present or not present • One picture on the table that’s a “cat” Say touch “cat” and they do • Not very useful for children with autism • That kind of trial becomes stimulus independent which is what you DON”T want to happen

Conditional Discrimination • A response to a given stimulus is followed by a reinforcer if and only if another stimulus is present • Said another way…a stimulus is discriminative for reinforcement or not, depending on (conditional on) the presence of another particular antecedent • Often taught via Match-to-Sample procedures • Many programs consist of Identity Matching (matching identical stimuli): • Objects • Pictures • Letters • Shapes • Colors • Numbers

Match-to-Sample SD/S+ SΔ/S- SΔ/S- Then responds to one of the comparison stimuli Sample Learner 1st responds to sample (conditional stimulus)

Match-to-Sample SD/S+ SD/S+ Sample (Conditional Stimulus) Sample (Conditional Stimulus)

Establishing New Forms of Conditional Stimulus Control • Identity matching (single mode) • Visual: visual • Auditory: auditory • Arbitrary matching (multimodal) • Visual: auditory • Auditory: visual • Auditory: tactile

Arbitrary Matching • Stimuli are not physically identical • Examples • Match non-identical visual stimuli • Object to pic, printed word to picture, object to printed word • Match auditory stimulus to visual stimulus (“Receptive Identification”) • Others?

Receptive Picture ID SD/S+ SD/S+ “baby” “flower” Sample Sample

Discrimination in the Laboratory. • Many laboratory discrimination procedures have focused on understanding exactly which stimuli or which aspects of stimuli control responding. • Several laboratory procedures have been developed that allow us to isolate these stimulus control factors. • Matching-to-Sample. • Equivalence Class Formation.

Concept Formation • Definition: Complex stimulus control that results in generalization within a class of stimuli and discrimination between classes of stimuli (Keller & Schoenfeld, 1950).

Two Procedures to Teach Concept Formation: • Simultaneous Discrimination: • Definition: The concurrent presentation of multiple stimuli • Successive Discrimination • Definition: The successive presentation of stimuli • In applied settings, simultaneous discrimination training should be used –why? • The individual has access to all relevant stimulus cues at one time • An on the spot comparison of choices is permitted • Produces better generalization (Schroeder & Baer, 1972)

Classroom Teaching Procedures. • Classroom teaching is more complex than the laboratory. • Suggestions for improving discrimination training • Evaluate stimuli carefully to promote control of relevant antecedent cues • Rotate stimulus placement randomly • Change auditory stimuli frequently • Be sure that the S+/S- functions of stimuli change randomly • Teach with a variety of stimuli to promote discrimination between categories (and generalization within categories) • Never, never teach in isolation!!

Classroom Teaching Procedures. • NEVER, NEVER, NEVER teach in isolation!!

Stimulus Class • Stimulus Class: set of stimuli that have a common effect on behavior (evoke the same response class) These would probably be in the same stimulus class for most people

Concept Formation • Complex stimulus control that results in: • Generalizationwithin a class of stimuli and • Discriminationbetween classes of stimuli

Stimulus Equivalence • Emergence of accurate responding to untrained and nonreinforced stimulus-stimulus relations • Following the reinforcement of responses to some stimulus-stimulus relations • 3 aspects • Reflexivity • Symmetry • Transitivity A B C DOG “dog”

Reflexivity • In the absence of training, person selects an identical stimulus (AKA Generalized identity matching) • Logicis…A = A • For example • Without specific training, the person matches

Symmetry • After being taught to match A to B, person can match B to A (without training) • Logic is…If A = B, then B = A • For example • After being taught to match to • Person can match to DOG DOG

Transitivity • Critical test for stimulus equivalence – if you get transitivity, the stimuli are members of an equivalence class • After being taught to match A to B and B to C, person can match A to C (without training) • Logic is…If A = B and B = C, then A = C • For example… • After being taught to match • to AND • to “dog” • Person can match to “dog” DOG DOG

Factors Affecting the Development of Stimulus Control • Reinforcement • Differential reinforcement with rich schedules of reinforcement • Preattending Skills • Looking at instructor or materials, sitting up tall, no stereotypy

Factors Affecting the Development of Stimulus Control • Stimulus Presentation • Specificity of directions • Should relate to response definition • Opportunity to response • Frequent, active opportunities to respond (active student learning) correctly leads to higher rates of academic achievement • Pacing of response opportunities • Higher pace often leads to superior performance and less off-task behavior

Factors Affecting the Development of Stimulus Control • Salience of the stimuli • Influences attention and ultimately the development of stimulus control • Dependent on the capabilities of an individual, the past history of reinforcement, and the situation • Multiple intelligences: some respond to instructional stimuli in the visual modality more than the oral. • This research has generated mixed results but it is important to rule out sensory deficits and assess modality strength

Factors Affecting the Development of Stimulus Control • Masking and overshadowing • Masking –even though one stimulus has control over behavior, another stimulus blocks that control from being expressed • E.g., Student knows answer but won’t answer in front of peers • Overshadowing –the presence of one stimulus condition interferes with the acquisition of control by another stimulus • E.g., hallway may be more interesting that teacher’s presentation in the front of the classroom • Ways to overcome include to make changes to physical environment, make instructional stimuli as intense and centrally located as possible, reinforce behavior in the presence of the instructionally relevant stimuli

Stimulus Control