PSYC207 Lecture Notes - Lecture 10: Demand Characteristics, Observer-Expectancy Effect, Internal Validity

• School: University of Delaware
• Department: Psychology
• Course: PSYC207
• Professor: Eric Splan

Document Summary

Interrogating internal validity is the priority for experiments. Design confound: another variable happens to vary systematically along with intended independent variable. Selection effects: different independent groups have systematically different types of participants. Order effects: only within-groups designs, outcome might have been caused by the order in which the levels of the independent variable are presented. Six threats to internal validity that especially apply to one-group, pretest/posttest designs. Three threats to internal validity that can apply to any experiment. Six threats to internal validity especially applies to one group, pretest/posttest group. Change in behavior that emerges more or less spontaneous over time. Grow to become more mature over time not due to some outside intervention. Difficult to tell whether the results occurred from the intervention, or just because of maturation. When a historical or external (to the experiment) event occurs to everyone in the treatment group at the same time as the experiment.