Stimulus Control Advanced Applied Behavior Analysis Presentation Based on Green (2001) and Chapter 17 of Cooper, Heron

1. Stimulus Control Advanced Applied Behavior Analysis Presentation Based on Green (2001) and Chapter 17 of Cooper, Heron, and Heward (2007)

2. Background • Contrary to popular myths about ABA, much of the basis for our current teaching technologies in stimulus control were already present in early pioneering work at U of Washington • See early work of Bijou, Hart, Risley, Baer, etc. • “generalization” and “antecedent control” were present a LONG time ago in comprehensive ABA programs

3. Antecedent Stimuli • SD v. prompt • Both are defined by FUNCTION, not whether the instructor labels them as such! • “I used a prompt but it didn’t work.” • 3-term contingency and relationship to term “trial” (I prefer “learning opportunity”!)

4. “Power” of Antecedent Stimuli • Stimuli presented prior to a reinforced response will increase the likelihood of that response in the future. Period! • If the stimulus could talk, it would be saying “Hey, remember that when I’m presented you should do X and that you’ll get a reward if you do? Remember that? Huh? Hey…Stop looking at that other thing!! Look at me!”

5. Stimulus Control • Terms refers to both a process and a field of study • In the former, it is the degree to which antecedent stimuli affect the likelihood of a response occurring • In the latter, it is the study of the variables responsible for that process

6. Stimulus Control • Stimulus Discrimination • Stimulus Generalization

7. 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

8. 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

9. 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

10. 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?”

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

12. The Need for Discrimination • Different antecedent stimuli often SHOULD differentially affect responding • If this is not occurring, then we need to teach discrimination among stimuli • Useful to be able to task analyze “discrimination” (it is much more complex than many interventionists are aware)

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

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

15. 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. • 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!

16. 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.

17. 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

18. “Simple” Discrimination • I would argue that really is no such a thing but traditionally this refers to a fairly constant 3-term contingency: • simplest way to teach discrimination is to reinforce a specific behavior in one situation (SD) and withhold reinforcement in the other (SΔ) • “Stimulus control” refers to a change in behavior that occurs when either an SD or SΔ is presented. • SD presented = probability of target response increases; • SΔ presented = probability of same response decreases.

19. “Simple” Successive Discrimination • One method is to arrange the presentation of SDs and SΔs so that one follows the other (called successive discrimination training). • Teach behavior that is appropriate for each SD (or teach learner NOT to respond to an SΔ) • See simple example next…

20. Learner receives reinforcement for taking the money

21. Learner receives NO reinforcement for taking the ball

22. “Simple” Simultaneous Discrimination • In alternative procedure, simultaneous discrimination, the SD and multiple SΔs are presented at the same time and the learner responds to the SD.

23. Learner receives NO reinforcement for taking the clock or ball Learner receives reinforcement for taking the money

24. Matching or Conditional Discrimination • In conditional discrimination training, the presence of a “sample stimulus” that changes from one trial to another (such as different instructions given to a learner) dictates which of two or more “comparison stimuli” the learner should select. • In reality, this is what MOST real-world discriminations involve: the IF-THEN nature of the conditional discrimination

25. One sample trial Another trial “Pick the money” “Pick the ball” Learner receives reinforcement for taking the ball Learner receives reinforcement for taking the money

26. Conditional Discrimination • behavioral function of an antecedent stimulus (i.e., the nickel or ball in the previous slide) changes depending on the presence of another stimulus (the different instructions in the previous slide). • That is, sometimes a stimulus is an SD for pointing to it (or taking it) and in other situations is the SΔ for pointing to it (or taking it) • the correct response is “conditional on” (dependent on) another antecedent stimulus • CONDITIONAL DISCRIMINATION is an “IF-THEN” rule

27. Conditional Discrimination = Matching To Sample • Because the conditional stimulus is referred to as a SAMPLE and the choices we respond to are called COMPARISON STIMULI, this is also called MATCHING TO SAMPLE (MTS) • because learner needs to make a specific response to a specific comparison in the presence of a specific sample • Examples…

28. Conditional Discrimination = Matching To Sample • Identity matching (match one thing to itself)

29. Conditional Discrimination = Matching To Sample • Perceptual similarity-based matching (e.g., match one dog picture to a similar dog picture)

30. Conditional Discrimination = Matching To Sample • Arbitrary matching (e.g., match one dog picture to dissimilar stimulus such as a word) DOG HOP CAT

31. Possible Confounds in Conditional Discrimination (MTS) Training • Also called “extraneous stimulus control” • That is, something other than the teacher-defined antecedent stimuli is controlling behavior • Often times, extraneous control can APPEAR to be “proper” stimulus control • Let’s examine the following trials…

32. CAT

33. CAT

34. CAT

35. What’s the problem? • Assuming you saw those 3 trials, would you say that the learner can match the written word CAT to a picture of a cat? • What function might the sample or conditional stimulus (written word CAT) be serving? • What is the problem with arranging trials in isolation this way?

36. What’s the problem? • Now look at these 3 trials…

37. CAT

38. DOG

39. HAMSTER

40. What’s the problem? • Assuming you saw those 3 trials, would you say that the learner can match the written word to corresponding picture? • What function might the sample or conditional stimuli (written words) be serving? • What is the problem with arranging trials in this way?

41. What’s the problem? • Now look at some more trials…

42. DOG

43. DOG

44. DOG

45. What’s the problem? • Assuming you saw those 3 trials, would you say that the learner can match the written word DOG to the corresponding dog picture? • What function might the sample or conditional stimulus (written word) be serving? • What is the problem with arranging trials in this way? • ARE THE NOVEL DISTRACTORS RELEVANT??

46. What’s the problem? • Here are some more trials

47. DOG

48. DOG

49. DOG

50. DOG