Testing effects, also known as order effects, only occur in experimental and quasi-experimental research designs that have more than one stage; that is, research designs that involve a pre-test and a post-test. In such circumstances, the fact that the person taking part in the research is tested more than once can influence their behaviour/scores in the post-test, which confounds the results; that is, the differences in scores on the dependent variable between the groups being studied may be due to testing effects rather than the independent variable.
