stimulus control. stimulus control is involved in… when to talk to strangers when to cross the...
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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.
Response:
Hold out picture of
spoon
Reinforcer:
spoon
SD:
Person in room
SΔ:
No one in room No spoon
Stimulus Control
Stimulus DiscriminationDefinition: 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 GeneralizationDefinition: 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?”
Response:
“red”Reinforcer:
“Super! You said red!”
SD:
“What’s your favorite color?”
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 behaviorSo 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
Stimulus GeneralizationIf you teach “green” using this color circle …
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 processesAs one increases, the other decreases
DiscriminationResponding differently to 2 or more
stimuliTight degree of stimulus control
GeneralizationResponding similarly to 2 or more stimuliLoose degree of stimulus control
Stimulus Discrimination and Stimulus Generalization are a
Continuum
Stimulus
Discrimination
Stimulus
Generalization
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 skillsReading.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 behaviorWe 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 autismThat 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
SampleLearner 1st responds to sample (conditional stimulus)
Then responds to one of the comparison stimuli
SD/S+ SΔ/S- SΔ/S-
Establishing New Forms of Conditional Stimulus Control
Identity matching (single mode) Visual: visualAuditory: auditory
Arbitrary matching (multimodal)Visual: auditoryAuditory: visualAuditory: 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?
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!!
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:Generalization within a class of stimuli
andDiscrimination between classes of
stimuli
Stimulus Equivalence
Emergence of accurate responding to untrained and nonreinforced stimulus-stimulus relationsFollowing the reinforcement of responses to
some stimulus-stimulus relations 3 aspects
ReflexivitySymmetryTransitivity
DOG “dog”
A
B C
Reflexivity In the absence of training, person selects
an identical stimulus (AKA Generalized identity matching)
Logic is…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