Pretest and Sensitization Effects in Curriculum Evaluation

The recent flurry of curriculum development activity sponsored in large part by the federal government has spawned a rapidly growing field of curriculum evaluation. Many evaluation studies rely on traditional research design procedures where the new curriculum (often called experimental) is compared to one that presently exists (usually referred to as traditional) on a set of selected criteria. Often the evaluators administer the criterion measures as pretests and posttests. This procedure raises two questions regarding the biases introduced in the posttest results. The first, termed the pretest effect, would lead to higher scores of those who take pretests because of item-practice effects. The second, termed sensitization, would lead to higher scores for only those in the experimental group who take the pretests because they learn what to concentrate on during their study of the experimental instructional materials as a result of having been exposed to the criterion. Unfortunately, both of these effects are largely speculative in curriculum research; although Solomon four-group designs have been proposed to deal with them, (Campbell and Stanley, 1963), there is little empirical evidence for them and even less that bears upon curriculum research.