Cogs 14A | Chapter 12: Single-Subject Designs

nomothetic research

conducted on __groups__ and attempts to identify general laws and principles of behavior

idiographic research

focuses on the behavior of an __individual__

case studies

* descriptions of an individual + their experiences
* NO systematic manipulation of an IV

single-subject designs

focus on one individual + manipulate IV

baseline measure

measurement of the DV taken prior to manipulation of IV (intervention)

baseline vs intervention measurements

* first, must have a stable baseline
* if intervention causes change, the change will be more apparent if the baseline is stable

single-subject time-series design

several measurements made before and after the introduction of the IV

* withdrawal design
* ABAC design
* ABCB design

withdrawal design (ABAB)

baseline → intervention → withdrawal → intervention

ABAC design

baseline → intervention → withdrawal → __second__ intervention

* compare effects of interventions

placebo effect

behavior being studied changes after intervention even though we know the intervention has no effect

ABCB design

baseline → intervention → placebo → intervention

* placebo effect when little change and B and C phase

reversal design

baseline → intervention → opposite intervention

alternating-treatments design

* between-series
* variation of ABAB, but does not require baseline
* two+ random/systematically ordered treatments presented to participant

multiple baselines design

effect of a treatment on two+ behaviors assessed or effect of a treatment on a single behavior is assessed across two+ situations

changing-criterion design

criterion changes as time progresses after being met for some time

threats to the internal validity of single-subjects design

* subject bias
* demand characteristics
* experimenter bias
* possible solution: test for placebo