1. Experimental Design ã Dependent variable (DV): Variable observed to determine the effects of an experimental manipulation (behavior) ã Independent variable (IV): Variable manipulated by the experimenter (environmental event or treatment) ã Confounding variable: Source of influence other than the IV that may produce changes in the DV ã Experimental design: Rules for applying an IV so as to examine its effects on a DV ã Functional relation: A relationship in which changes in one variable (DV) are demonstrated to be the result (a function) of changes in another variable (IV) ã Single subject design: An experimental design in which a functional relationship can be demonstrated with the behavior of only one subject ã Baseline: Condition in effect prior to introduction of the IV ã A-B notation system: “A” denotes baseline; subsequent letters (“B,” “C,” etc.) denote different IVs ã Replication: Duplication of earlier conditions in an experiment

2. A-B Design Definition: Single introduction of at least one IV on at least one baseline

3. A-B Design ã Definition: Single introduction of at least one IV on at least one baseline ã Advantage: Repeated measurement under BL (A) and Rx (B) conditions allows examination of changes in level, trend, and variability ã Limitations:  No replication  Therefore, does not rule out the influence of confounding variables  Therefore, no demonstration of a functional relation

4. Reversal Design (ABA) Definition: Introduction and subsequent removal of at least one IV on one BL

5. Reversal Design ã Definition: Introduction and subsequent removal of at least one IV on one BL ã Variations: ABAB, ABA, BAB, ABAC, etc. ã Advantage: Simple yet powerful demonstration of experimental control

6. Reversal Design (ABAB)

7. Reversal Design ã Definition: Introduction and subsequent removal of at least one IV on one BL ã Variations: ABAB, ABA, BAB, ABAC, etc. ã Advantage: Simple yet powerful demonstration of experimental control ã Limitations:  Detrimental effects of reversal: Ethical considerations  Irreversibility: Failure to reproduce effect observed in a previous phase even though conditions are arranged identically  Sequence/Order effect: Influence of a previous manipulation on responding in a later condition (e.g., training  contingencies)

8. Irreversibility (suspected)

9. Multiple Baseline Design Definition: Sequential introduction of an IV across more than one BL

10. Multiple Baseline Design ã Definition: Sequential introduction of an IV across more than one BL ã Variations: Across subjects, behaviors, settings ã Advantage: Does not require reversal to show experimental control ã Disadvantages:  Stability requirement more cumbersome than with a reversal design  Potential generalization across baselines (more likely with MBL across behaviors or settings)

11. Multiple Baseline Design (Apparent Generalization)

12. Multielement Design Definition: Rapid alternation of BL and IV conditions (or 2 or more IVs) on a single BL

13. Multielement Design (aka Alternating Treatments) ã Definition: Rapid alternation of BL and IV conditions (or 2 or more IVs) on a single BL ã Variations: BL vs. Rx, Rx1 vs. Rx2 (with or without BL), etc. ã Advantages:  Does not require baseline (although preferred)  Accommodates trends and instability  Minimizes sequence effects (limited exposure to one condition)  Ideally suited to complex analyses (parametric, component, comparative) ã Limitation: Multiple treatment interference

14. Multielement Design (Adv & Disadv)

15. Changing Criterion Design Definition: Introduction of one IV on a single BL in step-wise fashion, with steps corresponding to progressive changes in either response requirement or value of the IV

16. Changing Criterion Design ã Definition: Introduction of one IV on a single BL in step-wise fashion, with steps corresponding to progressive changes in either response requirement or value of the IV ã Advantage: No reversal and no additional baselines required to show experimental control ã Disadvantages:  Requires control over both direction and level of change  Requires careful selection of criterion change

17. Changing Criterion Design (Problems)