1. CHAPTER 11 Small N Designs

2. Research in Psychology Began with Small N
Most early research in psychology…
Small N
Data not summarized; data for each subject presented
Additional subjects used for replication
Dresslar’s facial vision study
Also a good example of falsification thinking

3. Reasons for Small N Designs
Misleading results from statistical summaries of grouped data
A failure of individual-subject validity
e.g., discrimination learning research in children
Grouped data  suggested gradual learning
Individual data  suggested hypothesis testing and quick solutions once proper hypothesis found
Solution  children reach criterion at different rates

4. Reasons for Small N Designs
Practical problems with large N designs
Participants with a particular attribute are rare
e.g., obsessive-compulsive disorder occurs in < 2% of population
Members of a specific animal species are rare, costly, or require much time for training

5. The Experimental Analysis of Behavior
Operant conditioning
Behavior conditioned, in a particular environment, by consequences (e.g., reinforcement)
Primary DV  rate of response
Recorded cumulatively

6. The Experimental Analysis of Behavior
Applied behavior analysis
Contemplative (understanding basic causes of events) vs. technological ideal (using science for control)
Skinner  using science to achieve control
The issue of control (Box 11.2)
Comparing Watson and Skinner
Attempt to improve society
Use of punishment for controlling self-destructive behaviors
Justified?
Judge Rotenberg Center

7. Small N Designs in Applied Behavior Analysis
Elements of single-subject designs
Importance of operational definitions (again); what constitutes a child’s “problematic behavior”?
Baselines established
Introduce some treatment
Simplest  A-B design
A = baseline
B = treatment
Withdrawal designs
A-B-A
Treatment (B) introduced, then withdrawn
To see if behavior change correlates with treatment change

8. Small N Designs in Applied Behavior Analysis
Withdrawal designs
A-B-A-B design
Treatment evaluated twice
Experiment ends with treatment in place
Ideal pattern:

9. Small N Designs in Applied Behavior Analysis
A-B-A-B design
Research example 34: Differential Reinforcement of Alternative Behavior
Peer reinforcement of on-task behaviors for ADHD children
External validity issue
Laboratory study might not generalize to classroom

10. Small N Designs in Applied Behavior Analysis
Multiple baseline designs
Three varieties of multiple baseline
One behavior, two or more subjects
Two or more behaviors, one subject
Two or more environments, one behavior, one subject

11. Small N Designs in Applied Behavior Analysis
Changing criterion designs
For behaviors that must be changed gradually
Operant principle of shaping

12. Small N Designs in Applied Behavior Analysis
Alternating treatments design
Compares relative effectiveness of two or more of treatments

13. Small N Designs in Applied Behavior Analysis
Evaluating single-subject designs
External validity issues
Visual inspection instead of statistical analysis, although this is changing
Hard to test interactive effects; effect on one type of person but not another?

14. Case Study Designs Detailed analysis of single individual or event
Incorporates other methods (e.g., observation, psychometric tests)
Individual
Both clinical and non-clinical cases
Effects of head trauma in boxer: Demonstrated targeted treatment plan for speech problems, independent of cognitive functioning
The mind of a mnemonist (Box 11.3), autstic savants
Event
Response to catastrophic event

15. Case Study Designs Evaluating case studies
Level of detail not found elsewhere
Can serve falsification (Remember Hans?)
Limited control
External validity issues
Faulty memory problems