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. 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+

16. 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.

17. 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-.

18. 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!

19. Peak Shift Effect – Hanson (1959)

20. 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

21. Spence’s Theory to Account for Peak Shift

22. 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.

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

24. 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

25. 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

26. 1 4
4 is the correct answer

27.
-1 5
.9 3
Using the last question and correct answer, which is the “best” answer?

28.
Now which is the best answer?
Let’s stick with “4”

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

30. 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

31. 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.

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

33. 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.

34. 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!

35. 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.

36. 2 Types of Discriminations.
Simple Discriminations.
Non-Conditional Discrimination.
Conditional Discriminations.
Matching-to-sample.
Arbitrary Discrimination.

37. 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

38. 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

39. 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

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

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

42. 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?

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

44. 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.

45. 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?

46. 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

47. 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

48. 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

49. 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

50. 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”

51. 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

52. 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

53. 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

54. 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

55. 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

56. Errorless Discrimination Learning:
Terrace: criticizes way most discrimination learning or training is conducted:
subjects allowed to make many, many errors
often get aggressive behavior occurring soon after transition from S+ to S-
even after long training durations, subjects till make many errors
Alternative suggestion: Errorless learning
subjects typically make fewer or no responses to S-
differs from traditional approach in two major ways:
rather than waiting for steady responding to S+, introduces S- early in learning
fading procedure used to make it unlikely that subjects will respond to S-

57. 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

59. RAT

60. RAT

61. RAT

62. RAT

63. RAT

64. RAT

65. RAT

66. 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

67. Feature Positive Effect
several limitations on effectiveness of discrimination training:
discrimination will not occur if animal cannot detect difference between stimuli
animal won't form discrimination if not attend to proper stimuli
the stimulus that an animal attends to is determined by many factors, including:
species differences
salience of stimuli
past experiences

68. Feature Positive effect: Jenkins and Hearst
basic experiment:
pigeons given 2 stimuli simultaneously
S+ = lighted key w/dark spot
S- = lighted key w/no dark spot
looked at discrimination ratio:
key pecks to S+/ total key pecks
thus: perfect dsicrimination ratio = 1.0
no discrimination = 0.5
results of initial experiment: pigeons quickly learned to discriminate

69. Feature Negative Effect
then: switched stimuli around:
S+ = lighted key w/NO dark spot
S- = lighted key w/dark spot
found NO discrimination in this case
Why? Feature Negative effect!

70. Feature Positive Effect

71. S+

72. S-

73. S+

74. S-

75. S+

76. S-

77. S+

78. Feature Negative Effect

79. S+

80. S-

81. S+

82. S-

83. S+

84. S-

85. S+

86. One more try!

87. S-

88. S+

89. S-

90. S+

91. S-

92. S+

93. S-

94. S+

95. S-

96. S+

97. S-

98. S-

99. So, what is the concept?

100. An Unusual Paragraph!
How quickly can you find out what is so unusual about this paragraph? It looks so ordinary that you would think that nothing is wrong with it at all, and, in fact, nothing is. But it is unusual. Why? If you study it and think about it, you may find out, but I am not going to assist you in any way. You must do it without coaching. No doubt, if you work at it for long, it will dawn on you. Who knows? Go to work and try your skill. Par is about half an hour.

101. A Clue
The author, Eliot Hearst, could not add his name to the paragraph and maintain the concept!

102. Vaughan and Greene (1973):
pigeons trained to classify slides as positive or negative
random- no concept involved
after 10 sessions, could classify 80 slides (40 + and 40-)
learned next 80 even faster
eventually worked up to 320

103. Herrnstein, 1976: Wanted to see if pigeons could categorize
Three categories:
Trees
Water
Person
Found that pictures being seen for first time (novel) discriminated as well as training pictures
Interestingly- similar patter of errors and correct discrimination across the pigeon subjects

104. What does this mean?
Ability to discriminate open-ended classes of stimuli poses problems at two levels:
Analysis of features enabling subject to tell whether object is member of particular class
Analysis of properties of classes that render them discriminable

105. What are they responding to?
Too complex to be common elements
Cluster of features that are more or less isomorphic-probabilistic conjunctions and disjunctions
Look like semantic categories of generalization

106. Pigeons as Art Critics
Birds: excellent visual acuity in comparison to humans!
But: use artificial settings for discrimination training
This study used “natural” stimuli- paintings
Difference between Monet and Picasso
Monet: landscapes, more realism
Picasso: Cubism, not “real”, much more sharp corners and edges

107. Experiment 1
Pigeons trained on discrmination between photos or videos of Monet and Picasso
8 pigeons
Projected pictures and then had to peck key underneath “correct” picture
10 paintings from each artist
Testing stimuli: novel paintings from Monet and Picasso, then from Cesanne, Braque and Delcroix
Second test similar with 3 other new artists

108. Experiment 1 Trained to 90% criterion
Test 1: color paintings of monet vs picsso
Test 2: presented paintings out of focus to obscure “edges”
Test 3: left right reversed
Test 3: novel stimuli of Monet, Picasso and other artists

109. Experiment 1 All subjects learned discrimination
Had preference for some paintings
Not color
Not edges or sharp outlines
little problem with mirror image and upside down images
Generalized to other impressionist paintings and cubist paintings
Evidence of both categorical and individual discriminations

110. Experiment 2 Trained to a pseudo concept discrimination 2 pigeons
Discriminate 2 arbitrary groups of paintings
Contained both Monet and Picasso pictures
2 pigeons
Same manipulation of stimuli
Both easily learned the task

111. What does this mean?
Pigeons’ discriminative performance could be controlled by different styles of paintings
No identified single cue for discrimination of paintings
Some decrease in responding for reversed or upside down paintings
Note: paintings had little if any ecological significance for pigeons-
Distortion tests:
More disruption when painting displayed real object (Monet) than abstract (Picasso)
Evidence that could discriminate both individual paintings and group them into categories
Evidence of Flexibility of categories

112. Gorillas and Natural Concepts
Several species of animals show ability to form concepts:
Pigeons
Parrots
Crows
Dolphins and whales
Seal lions
Dogs
Etc.
Question: is this a perceptual ability or cognitive ability?
Obviously, must have perceptual characteristics
To show cognitive ability must show ability to transfer learning to novel exemplars
These must vary across several dimensions
Evidence in nonhuman primates that they attend to local features, not global features (of concept)

113. Abstract vs. concrete concepts
Share many features
Easily discriminated along perceptual lines
Abstract concepts:
Share fewer features
Defined in terms of breadth of category to be learned
Fewer perceptual overlaps
Humans easily perform abstract concept formation
Question: do great apes also show this (since are our closest relatives)

114. Method Subject = 4 year old captive female lowland gorilla (Zuri)
Materials:
Photo sets: 10 S+ and 10 S- category exemplars
S+ and S- shared similar backgrounds, matched on as many features as possible
Minimized similar perceptual features across S+ and S-
Procedure:
Used Apple computer
10 S+ and 10 S- per session
Photo pairs randomly presented
Many sessions per day
Basically had to discriminate great apes vs. humans
Used first 2 sessions with novel photos to indicate transfer
Coded photos across several dimensions

115. Phase 1: concrete discriminations
Gorillas or orangutans vs. humans
Orangutans versus other primates
Orangutan color test
Could examine transfer by errors:
E.g., If responding by color: not show transfer to black and white photos

116. Phase 1: Results Orangutans versus other primates Gorillas vs. humans
Reached criterion in 14 sessions
Showed transfer
Orangutans vs humans
Reached criterion in 7 sessions
Better at pictures of adults than young apes
Orangutans versus other primates
Reached criterion in 19 sessions
No immediate transfer
Took 25 sessions on second rianing
Third set only 3 sessions
Orangutan color test
Reached criterion in 7 sessions
No transfer
Mastered second set in 2 sessions
Showed transfer to third
Gorillas vs other primates
Reached criterion after 16 sessions
High degree of transfer

117. Phase 1 results Could examine transfer by errors:
E.g., If responding by color: not show transfer to black and white photos
Could detect gorillas and orangutans vs humans
Not as good on orangutans vs other primates; gorilla vs other primates was good
Did not appear to be discriminating on basis of single feature, but instead was using multiple features
Still: could be concrete concepts rather than abstract

118. Phase 2: Intermediate discriminations
Primates vs. nonprimates
Mammals, reptiles, insects, birds, fish
Primate controls:
Used stimuli that she made many errors with
Results:
Primates vs. non primates
Reached criterion after 12 sessions
Not show transfer
23 sessions on second set
3 sessions on third set, with some transfer
Only age affected discrimination (as before)
Correct if primate photo was young animal
Incorrect if non primate photo was young animal

119. Phase 2: Intermediate discriminations
Zuri had more trouble with intermediate discriminations relative to concrete
Age affected ability to discriminate
More likely to select photos of species she had seen before or served as S+

120. Phase 3: Abstract Discriminations
Animals vs. non animals
Non animals = landscapes with neutral background
Food vs.. Animals
Results:
Animals vs non animals
12 sessions to criterion on first set
Showed transfer on all subsequent photo sets
Food vs animals
Quick to criterion
Good discrimination on initial transfer
Better at abstract discriminations!
Suggests may have been relying on perceptual qualities for concrete and intermediate, but could not for abstract
Why better at abstract than intermediate?
Within class and between class similarities interact to determine relative difficulty of discriminations at various levels of abstraction
Also: were artificial “human” discrminations…..don’t know meaning to gorillas
Showed excellent transfer, unusually so for a non human primate

121. Better at abstract discriminations!
Suggests may have been relying on perceptual qualities for concrete and intermediate, but could not for abstract
Why better at abstract than intermediate?
Within class and between class similarities interact to determine relative difficulty of discriminations at various levels of abstraction
Also: were artificial “human” discriminations…..don’t know meaning to gorillas
Showed excellent transfer, unusually so for a non human primate
Could not have been just memorizing
Some effect of experience: “learning to learn”