1. Stimulus Control
Chapter 17

2. What is stimulus control?
Stimulus control occurs when
The rate, latency, duration, or amplitude of a response is altered
In the presence of an antecedent stimulus
Stimulus control is acquired when
Responses are reinforced only in the presence of a specific stimulus
Known as the discriminative stimulus (SD)
And not in the presence of other stimuli
Known as stimulus deltas (S

3. The Development of Stimulus ControlSD
Response
SR+
Friendly conversation
Telephone rings
Pick up phone and say “hello”
Response S SO
Doorbell rings
Pick up phone and say “hello”
Friendly conversation withheld

4. Not to be confused with respondent conditioning
UCS
Response
Meat powder
Dog salivates
Neutral S
Response
Bell rings
Dog salivates
UCS
Meat powder

5. Not to be confused with respondent conditioningCS
Response
Bell rings
Dog salivates
Notice the absence of any consequence stimuli in this example.
Salivating is a respondent behavior.
Also notice that here control is established by pairing specific antecedent stimuli.

6. Stimulus Control and Motivating Operations
Similarities
Both events occur before the behavior of interest
Both events have evocative functions
However, they are different!

7. Motivating Operations
Remember, a motivating operation is something that changes the value of a stimulus as a reinforcer
Establishing operation (EO) makes the reinforcer more valuable
Abolishing operation (AO) makes the reinforcer less valuable

8. MOs and Stimulus ControlEO
SR- SD
Response
Difficult Worksheet
Task break provided
Teacher 1
Student displays aggression
Response SO EO S
Difficult Worksheet
Teacher 2
Student displays aggression
Task break withheld

9. Stimulus Generalization
Occurs when stimuli that share similar physical characteristics with the controlling stimulus evoke the same behavior as the controlling stimulus

10. Stimulus Discrimination
Occurs when new stimuli that are similar to the controlling stimulus do not evoke the same response as the controlling stimulus

11. Stimulus Control and Stimulus Generalization are a Continuum

12. 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

13. The Development of Stimulus ControlSD
Response
SR+
Friendly conversation
Telephone rings
Pick up phone and say “hello”
Response S SO
Doorbell rings
Pick up phone and say “hello”
Friendly conversation withheld

14. Concept Formation Not a hypothetical construct or mental process
Complex example of stimulus control that requires
Stimulus generalization within a class of stimuli
Stimulus discrimination between classes of stimuli

15. Example: Concept of Red
Stimulus generalization across all red objects
Light red to dark red
Different objects (car, ball, pencil)
Stimulus discrimination between red and other colors
Red ball vs. yellow ball
Red dress vs. blue dress

16. Teaching Concepts Requires discrimination training
Antecedent stimuli representative of a group of stimuli sharing a common relationship (examples) are presented, along with…
Antecedent stimuli from other stimulus classes (nonexamples)
So that the examples form a stimulus class

17. Types of Stimulus Classes
Feature stimulus class
Stimuli share common physical forms (i.e., topographical structures)
Stimuli share common relative relationship (i.e., spatial arrangements)
Developed through stimulus generalization
Arbitrary stimulus class
Do not share a common stimulus feature
Limited number of stimuli
Developed using stimulus equivalence

18. Stimulus Equivalence
The emergence of accurate responding to untrained and nonreinforced stimulus-stimulus relations following the reinforcement of responses to some stimulus-stimulus relations
Useful for teaching complex verbal relations
Reading
Language arts
Mathematics

19. Testing for Stimulus Equivalence
Must have a positive demonstration on 3 different behavioral tests that represent the following mathematical statement:
If A = B, and
B = C, then
A = C

20. Tests for Stimulus Equivalence
Reflexivity
Occurs when in the absence of training and reinforcement, a participant selects a stimulus that is matched to itself (A = A)
Matching to sample

21. Tests for Stimulus Equivalence
Symmetry
Occurs with reversibility of the sample stimulus and the comparison stimulus (if A = B, then B = A)
Teach spoken word “bicycle” =
Present and participant matches to
spoken word “bicycle” (as opposed to “car” or “airplane”)

22. Tests for Stimulus Equivalence
Transitivity
Requires demonstration of three untrained stimulus-stimulus sequences
A = B relation (spoken name = picture)
“Bicycle” (spoken name presented)
(Child selects picture)

23. Tests for Stimulus Equivalence
Transitivity
Requires demonstration of three untrained stimulus-stimulus sequences
B = C relation (picture = written word)
(picture presented)
bicycle
airplane
car
(Child selects written word)

24. Tests for Stimulus Equivalence
Transitivity
Requires demonstration of three untrained stimulus-stimulus sequences
A = C relation (spoken word = written word)
“bicycle”
(spoken word presented)
bicycle
airplane
car
(Child selects written word)

25. Matching-to-Sample Participant observes the sample stimulus
The comparison stimuli are then presented
Participant makes a selection response
Matches are reinforced
Nonmatches are not reinforced

26. Matching-to-Sample Conditional discrimination training
Same selection must be correct with one conditional stimulus, but incorrect with one or more other sample stimuli
Sample 1
Sample 2

27. Factors Affecting Stimulus Control
Consistent use of reinforcers contingent upon correct responding in the presence of the SD is critical
Also important are:
Pre-attending skills
Stimulus salience
Masking and overshadowing

28. Pre-attending A prerequisite skill for stimulus control
Looking at instructional materials
Looking at teacher when responses are modeled
Listening to oral instructions
Sitting quietly for short periods of time
These may need to be taught before stimulus control procedures are implemented

29. Stimulus Salience Prominence of the stimulus in the environment
Increased saliency facilitates efficiency of instruction

30. Masking and Overshadowing
Increase or decrease salience of stimuli
Competing stimuli may block the evocative function of an SD
To limit the negative effects of these:
Rearrange the environment
Make instructional stimuli more intense
Consistently reinforce behavior in the presence of instructionally-relevant stimuli

31. Using Prompts
Supplementary antecedent stimuli used to occasion a correct response in the presence of an SD (that will eventually control behavior)
Response prompts operate directly on the response
Stimulus prompts operate directly on the antecedent task stimuli

32. Response Prompts Verbal instructions Modeling Physical Guidance Vocal
Non-vocal (e.g., written)
Modeling
A demonstration of the desired behavior
Physical Guidance
Partially physically guide the student’s movements
Intrusiveness increases

33. Stimulus Prompts Movement cues Position cues Redundance
Pointing, tapping, touching, looking at
Position cues
Place one stimulus closer to the student
Redundance
Stimulus or response dimensions are paired with correct choice

34. Transfer of Stimulus Control
Prompts should be used only during acquisition
Transfer stimulus control from prompt to naturally-existing stimuli quickly using fading

35. Transferring from Response Prompts
Most-to-least prompts
Physically guide participant through entire performance
Gradually reduce amount of physical assistance
Modeling
Verbal instruction
Natural stimulus

36. Transferring from Response Prompts
Graduated guidance
Immediately fade physical prompts
Follow participant closely with hands
Gradually increase distance between hands and participant

37. Transferring from Response Prompts
Least-to-most prompts
Provide participant with an opportunity to perform the response with the least amount of assistance on each trial
Participant receives greater degrees of assistance with each successive trial without a correct response

38. Transferring from Response Prompts
Time delay
Varying the time interval between presentation of a natural stimulus and the presentation of a response prompt
Constant time delay
Begin with a 0-sec delay
Then use a fixed delay (e.g., 3 sec)
Progressive time delay
Gradually and systematically increase delay (e.g., in 1-sec intervals) according to some rule

39. Transferring from Stimulus Prompts
Stimulus fading
Highlighting a physical dimension of a stimulus and then gradually fading that exaggerated dimension
Superimposing one stimulus on top of another and gradually fading it out

40. Transferring from Stimulus Prompts
Stimulus shape transformations
Use an initial stimulus shape that will prompt a correct response
This shape is gradually changed to form the natural stimulus, while maintaining correct responding