Overview
The lecture covers single-subject research designs in behavior modification, comparing their advantages and limitations to group designs, and explains various design types with practical examples.
Principles of Experimental Design
- All subjects in an experiment should receive comparable experiences for valid results.
- Group experiments may require uniform procedures, which might not fit all participants.
- Single-subject designs allow real-time modifications if individuals do not respond as expected.
Limitations of Group and Single-Subject Designs
- Group designs may fail to account for outside events influencing behavior (e.g., pandemic effects).
- Group studies rely on statistical methods to control variability and compare between groups.
- Some effects can only be studied through group comparisons, not single subjects.
- Single-subject data analysis is less statistically advanced than group analysis.
Baseline and Comparison Designs
- In single-subject research, behavior before treatment (baseline) is measured for stability.
- The baseline predicts future behavior if no treatment is applied.
- The AB (comparison) design compares baseline (A) to treatment (B) phases.
ABA and ABAB Designs
- ABA design involves adding and then removing treatment to observe reversibility.
- ABAB (replication) design repeats treatment to strengthen evidence for its effect.
- Ethical and practical issues may limit the reversibility of some treatments.
Alternating Treatments Design
- This design compares the effectiveness of multiple treatments by alternating them across sessions.
- Treatments should be randomly assigned to avoid confounds like time of day.
Multiple Baseline Design
- Multiple baseline design staggers the introduction of treatment across behaviors, subjects, or settings.
- Useful when behavior change is irreversible or withdrawing treatment is unethical.
- Clearly links changes in behavior to the introduction of treatment.
Changing Criterion Design
- The behavior criterion for reward is raised incrementally after stabilization at each level.
- Demonstrates the effect of treatment when behavior change cannot or should not be reversed.
Key Terms & Definitions
- Single-Subject Design — Experimental research focusing on individual participants rather than groups.
- Baseline — Pre-intervention measurement used as a reference for post-treatment comparison.
- AB Design — A research design comparing baseline (A) to treatment (B).
- ABA Design — Baseline, treatment, then return to baseline sequence.
- ABAB/Replication Design — Treatment is reintroduced after withdrawal to confirm effects.
- Alternating Treatments Design — Different interventions are alternated to compare their effects.
- Multiple Baseline Design — Treatment is introduced at different times across multiple behaviors or settings.
- Changing Criterion Design — Stepwise changes in behavioral goals to demonstrate treatment impact.
Action Items / Next Steps
- Answer the week's discussion questions.
- Submit part two of the research paper combined with part one as a single document.
- In the discussion section, follow the structure set by your literature review/introduction.
- Address instructor comments in your revised paper.
- Suggest future research directions in your discussion section.