The Solomon four-group design is an experimental design that assesses the plausibility of pretest sensitization effects, that is, whether the mere act of taking a pretest influences scores on subsequent administrations of the test. For example, if respondents complete a questionnaire measuring their knowledge of science as a pretest, they might then decide to subsequently seek answers to a few unfamiliar equations. At the posttest they might then score better on the science test compared to how they would have scored without taking the pretest. Meta-analytic results suggest that pretest sensitization does occur, although it is more prevalent for some measures than others, and the more time passes between pretest and posttest, the less likely a testing effect will occur.

In the Solomon four-group design, the ...