Pretesting as Determinant of Attitude Change in Evaluation Research

Abstract

Two experiments were done to study the biasing effects of a pretest on subsequent posttest results. The problem of the first experiment was the evalua tion of a programmed textbook used by psychology freshmen. It used a separate-sample pretest-posttest design and showed that a pretest containing mostly negative statements on programmed instruction confounded posttest results. The second experi ment, using a different treatment, studied the pre test effects of positive or negative statements. The positive version counteracted the development of negative feelings towards the treatment. The negative version did not show a similar sensitizing effect. This was considered a consequence of the rather controversial character of the treatment and the obligatory participation of subjects. The nega tive statements perhaps confirmed existing at titudes. Three suggestions to control for pretest sen sitization effects were given: (1) use research de signs with control conditions; (2) separate the pre test phase from the posttest phase; and (3) give more emphasis to designs without pretests.