1. Stimulus Control

2. Stimulus Control of Behavior
Having stimulus control means that the probability of the behavior varies depending upon the stimuli present.
If a behavior is under stimulus control then
The behavior happens when the stimulus is present
The behavior doesn’t happen when the stimulus is absent
Most of our behavior is under stimulus control
A person that contributes to charity generously while in church may watch every penny spent while at work

4. 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

5. 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

6. 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

7. 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?”

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

9. 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

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

11. Stimulus Generalization
If 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)

12. Stimulus Generalization
Stimulus Generalization is more likely when:
Stimuli that are highly similar to the original stimulus are presented.
E.g., similar people, materials, or settings
The more similar the novel person, materials, and setting are to the training person, materials, and setting…

13. Discrimination vs. Generalization
Essentially opposite processes
As discrimination increases, generalization decreases
As discrimination decreases, generalization increases
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

14. Stimulus Discrimination and Stimulus Generalization are a Continuum
Generally, as the training and test stimuli become more different responding will decline,
Produces a generalization gradient

15. How to test generalization
Train
GeneralizationTest T+
No reinforcers
Present tones of varying frequencies and examine lever pressing in response to each tone
T = 1000hz tone

16. Generalization Gradient Guttman & Kalish (1956)
pigeons reinforced for pecking a 580 nm lit key (orange-yellow) (S+) on a VI schedule
A test session was then given where many different colored key lights were presented in extinction S+

17. Interpreting Generalization Gradients
Pigeons trained to peck a moderately bright light (S+) to get food.
(S- = dim light)
After asymptote is reached, present occasional non-reinforced probe trials at various wavelengths or levels of brightness.

18. Excitatory and inhibitory gradients
Excitatory gradients form around the CS+; show where responding is MOST likely
Inhibitory gradients also form; show where responding is least likely
e.g., Pigeons trained to peck at a 800 hz tone (S+), with a 500 nm light S-.

19. Peak Shift
Phenomena where the peak of the generalization curve shifts AWAY from the S-
Means that the most responding does not occur for the S+
But slightly offset from the S+ and away from the S-
Question is WHY!

20. Peak Shift Effect – Hanson (1959)

21. 1 4
4 is the correct answer

22.
-1 5
.9 3
Using the last question and correct answer, which is the “best” answer?

23.
Now which is the best answer?

24. Now which is the “best” answer?
8 32

25. Spence’s Theory
Spence: Peak shift occurs because of the summation of the excitatory and inhibitory curves
Result is that the most responding is slightly in favor of the S+
Not as strong of suppression for S-
Thus, get shift away from S-
Just a math phenomenon

26. Spence’s Theory to Account for Peak Shift

27. Interdimensional theory
Kohler’s Transposition or Interdimensional theory
The animal learns a conceptual rule
“Not” the S- but is the S+
Thus, when given generalization stimuli, take whatever is the most “not” S-
Shift away from S+ occurs
Learning a concept: always choose larger or greener, etc.

28. Interdimensional discrimination
Increase in peak height and sharpness, but no peak shift.
Discrimination: S+ = 555nm Light; S- = Tone

29. Test of Theories Choose between squares: S+ S- Situation:
100 cm cm original training
250 cm cm2 Test 1: Spence’s test
500 cm cm2 Test 2: Kohler’s test
1000 cm cm ??????
Spence's prediction: will choose closest to original S+
Transposition or interdimensional: choose larger

30. Which is correct?
tests for transposition yield evidence supporting transposition
tests for generalization yield evidence supporting Spence
 probably: both effects working part of the time

31. So, what is a stimulus? Any sensory event that elicits a response
A cue that a response contingency is now in place (or not in place)
A cue that predicts an upcoming event
Establishing a cue
Classically condition (cue to cue)
Operant conditioning: response to reinforcer, then add predictive cue for contingency

32. Teaching Stimulus Discrimination
Discrimination is a fundamental process that controls behavior.
Discrimination allows us to differentiate when reinforcement is available for specific responses.
For example, saying the word book when the teacher points to a book will result in reinforcement. Saying car when the teacher points to a book will not result in reinforcement.
Also red light on the soda machine example.

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

34. 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.

35. 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!

36. 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.
need to be careful how we teach and what stimuli we use.

37. 2 Types of Discriminations.
Simple Discriminations.
Non-Conditional Discrimination.
Conditional Discriminations.
Matching-to-sample.
Arbitrary Discrimination.

38. 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

39. 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

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

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

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

43. 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?

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

45. 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.

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

47. 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 1 time
An on the spot comparison of choices is permitted
Produces better generalization (Schroeder & Baer, 1972)

48. Real World Teaching Procedures.
Real World 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!!

49. 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

50. Concept Formation Complex stimulus control that results in:
Generalization within a class of stimuli and
Discrimination between classes of stimuli

51. 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”

52. 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

53. 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

54. 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
or to “dog”
Person can match to “dog”
DOG
DOG
DOG

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

56. 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

57. 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

58. 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

59. What is a stimulus Any sensory event that elicits a response
Not necessarily the response you want
Need to know that that rat perceives the stimulus
Establishing a cue
Classically condition (cue to cue)
Operant conditioning: response to reinforcer, then add predictive cue for contingency

60. Shaping the cue Need to shape the response to the cue
Introduce the stimulus cue right when the behavior occurs
Not as it is starting, not after
E.g., for a dog to learn “sit”, not when it is walking, but when it starts to sit.
BUT: click once the behavior is underway, not when the behavior is finished
Then, only introduce the cue when the dog is NOT doing the behavior
Give the cue
Get the behavior
click

61. Four rules for stimulus control
Behavior occurs immediately upon presentation of the cue stimulus
Behavior never occurs in absence of stimulus
Behavior never occurs in response to another stimulus
No other behavior occurs in response to the stimulus

62. Transferring stimuli
Once establish one cue, can add a second cue for the same behavior
Again, use only for THAT behavior
Keep stimuli separate.
E.g., does down mean stop jumping on me or lie down on the ground?

63. Prompting
Prompts used to increase probability that organism will engage in correct response
Use during discrimination training
SD or S+: in presence of this stimulus, do the behavior
S or S-: in the presence of this stimulus, do NOT do the behavior
Function of prompts is to produce instance of correct behavior so it can be reinforced

64. Types of Response prompts
Response prompts: behavior of another evokes desired response in presence of SD
Verbal prompts: voice command
Gestural prompts: physical movement or gesture of trainer
Modeling prompts: observe model and imitate (not really used with rats)
Physical prompts: physically assisting rat to engage in behavior

65. Types of Stimulus prompts
Stimulus prompts: change in stimulus or addition/removal of stimulus increases likelihood of desired response in presence of SD
Within-Stimulus prompts: change the salience of a prompt
Bigger or smaller
Louder or softer
More or less
Extra-stimulus prompts:
Adding a stimulus to increase likelihood of correct discrimination
Picture prompts
Putting line of food pellets for rat to follow

66. Aversive cues Use aversive to STOP behavior
E.g., “no”, a sharp noise, a table slap correction
Good for dangerous behaviors
Potential downside:
Squelch behaviors
Organism is startled, now won’t move
More likely to bite/nip/freeze

67. Limited holds and anticipation
Reinforcer only available in a narrow window
Either take it now, or lose it
Often used to avoid stashing or lazy choice
If do behavior, can get reinforcer within x seconds or less, otherwise lose it.
Anticipatory behaviors occur before the cue
If occur, cancels the trial
Withdraw target stick and even put rat in “time out”

68. Behavior chains One behavior can be a cue for the next response
This is a behavior chain
E.g., run through the tunnel, over the balance beam and then through the weave poles
Can teach forward chain:
Start with first, then add second, third, etc.
Reinforce after successful behavior for criterion
Or backwards chain:
Start with last response, then next to last, and so on

69. Generalization
May want organism to engage in behavior in many settings/situations/cues
E.g., go over balance beam on desk or in either of the two big boxes
Must train so that the cues to which the rat attends are the ones relevant to the task, not the setting

70. Fading prompts Important to fade prompts Several ways to fade prompts:
Want behavior to occur to cue only
Shows mastery of behavior:
Behavior flows well
Behavior occurs at high rate (or low rate if that is goal)
Occurs evenly and consistently
Several ways to fade prompts:
Transferring stimulus control
Remove response

71. Fading prompts Several ways to fade prompts:
Transferring stimulus control
Remove one stimulus cue, then another
Fading across different types of prompts or fading across prompts
Least to most: fade least invasive prompt first
Most-to-least fading: fade most invasive prompt first
Prompt delay
Delay the prompt
Increase delay until behavior occurs before prompt would have been given

72. example: teach S+ = red; S- = green
Teaching red vs. green discrimination
S- presented for only 5 or so seconds
S+ presented for 3 minutes
S- begins as unlit (dark) key: pigoens much less likely to peck it
S- gradually fades to green key
human example: teaching MR children sight words
word + picture on slide
gradually fade the picture, leaving only the word

74. RAT

75. RAT

76. RAT

77. RAT

78. RAT

79. RAT

80. RAT

81. Several important characteristics about procedure:
is very effective in reducing number of responses to the S-
improves long term discrimination
Terrace claims not get aggressive behaviors w/fading procedure
S- not develop inhibitory properties- thus eliminates peak shift effect
not get behavioral contrast