1 Chapters 10 & 11 (Richards text) CHANGING CRITERION Designs in Single-Subject Research Ps534 Dr. Ken Reeve Caldwell College Graduate Programs in ABA

2 Review: Single-Case Experimental Designs Issues For each design we will ask the following:  Does the design allow us to see a change in DV (without regard to whether it was caused by the IV)? YES  Does the design allow us to infer a functional relationship between IV and DV? YES  Why does it allows this? WE’LL FIND OUT  What threats to internal validity (confounds) does the design control for?  What ethical issues are important to know about using a particular design?

3 CHANGING CRITERION Designs Main Purpose: We examine the effects of one IV (treatments) on a SINGLE DV (target behavior) Specifics: 1. Usually used with a target behavior the person already has in their repertoire 2. And we want to dramatically increase or decrease the target behavior (rate, duration, frequency, % correct, magnitude) 3. And it is a behavior that is usually very difficult to change a great deal all at once (studying, smoking, cursing, over-spending) 4. Frequently used in self-management interventions

4 How To Do CC Designs  Begin with single participant (each participant is a SEPARATE experiment and serves as his or her own control like in a withdrawal design)  MUST take baseline to demonstrate experimental control (phase A)  Prior to initial treatment step (phase B 1 ), you must determine two different criteria: –a) criterion to move to next treatment step and –b) final goal criterion  Learner must reach step criterion for at least 2/3 occasions before next treatment step (phase B 2 ) is implemented  Continue on with treatment phases B 3 …B X  Stop when final goal criterion is reached

5 Sample CC design Phase A B 1 B 2 B 3 B 4 B 5

6 Issues Using CC Designs  You should vary each treatment phase to control for confound of person simply changing behavior when a certain number of days goes by (as opposed to the person’s behavior actually being controlled by the changes in response requirements  Longer phases are needed for slow-to-change behaviors  Shorter phases are okay for quick-to-change behaviors  More…

7 Issues Using CC Designs  How much of a step increase in response requirements is desirable?  Clinically, the quicker you get to the goal the better BUT if you step up too fast then it is too difficult to succeed so better to be conservative  There are formulas to determine the steps but there are no studies demonstrating what step size is most desirable (thesis or dissertation anyone?)  Usually the first step in treatment is the average of the baseline responding (or slightly higher than the average)

8 “Reversals” in CC designs (step down)  To increase internal validity (demonstration of functional relationship), you can step down the requirements to see if behavior drops  This is a GREAT control for maturation & practice effects, in particular

9 “Reversals” in CC designs (back to baseline)  Experimentally, it is even better if you reverse back to baseline instead of just stepping down response requirement (assuming behavior will drop a lot)  Clinically, though, this may not be as ethical Not shown in this graph but imagine that the “reversals” are return to baseline

10 Design a study using CC Design  Question: You wish to decrease the frequency of cigarette smoking in an adult group home resident who currently smokes 60 cigarettes a day and has been doing it for 20 years.  The resident already uses a token motivational system to earn access to leisure activities  How would you do it?

11 End