The Inhibitory and Enhancing Influence of Pretest Commitment

Abstract

Sixty subjects, 30 volunteers and 30 nonvolunteers, participated in an experiment examining pretest sensitization effects. Two interpretations of these effects—the commitment hypothesis and the demand interpretation—are explored. A variation of the Solomon four-group design was employed and an interaction between pretesting and the type of communication used was hypothesized. The hypothesis was confirmed. The possibility of using the GSR as an indicator of sensitivity in the pretest design was further explored. Heightened GSR activity was found for pretested when compared with unpretested subjects.EDUCATIONAL AND PSYCHOLOGICAL MEASUREMEN1 1974, 34, 857-869. FOR a number of years psychologists have been intrigued by the influence of the pretest in studies employing a before-after design (Campbell and Stanley, 1966;Hovland et al., 1949Hovland et al., , 1957Lana, 1966Lana, , 1969Solomon, 1949). One of the consistent findings in this research has been that the administration of a pretest tends to inhibit attitude change if it has any effect at all. The type of communication which a subject receives (Lana, 1966) and the motivation of the subject who receives it (Rosnow and Suls, 1970) are major factors inherent in such a phenomenon. Type of Communication Persuasive communications can either be unidirectional or bidirectional. A unidirectional communication presents a subject with a persuasive argument in favor of one side of an issue. A bidirectional 1 The authors wish to thank Ralph Rosnow, Robert Menapace, and Jerry Suls for most usefully commenting upon the study. at Harvard Libraries on June 30, 2015 epm.sagepub.com Downloaded from 858 EDUCATIONAL AND PSYCHOLOGICAL MEASUREMENTcommunication offers subjects opposed arguments on both sides (pro and con) of an issue (for example, a television debate between two political candidates with opposing ideological views) or offers a brief qualification of the main assertion of an unqualified persuasive statement (e.g., Hovland, Lumsdaine, and Sheffield, 1949). To date, the pretest depressive effect has generally been limited to those studies employing a bidirectional communication (Lana, 1966(Lana, , 1969Lana and Rosnow, 1963). Typically, there is an enhancement effect or no effect at all when a pretest is associated with a unidirectional communication (Lana, 1959;Lana and Menapace, 1971;Solomon, 1949).One explanation of the enhancement effect accompanying unidirectional communications can be made in terms of the demand characteristics (Ome, 1969) of the before-after design. A study which uses a pretest-treatment-posttest procedure may encourage subjects to change their opinions regardless of the nature of the persuasive argument since subjects probably perceive the intent of the experimenter to be consistent with the presentation of a persuasive communication. This would facilitate heightened attitude change in cases where the persuasive communication directly follows the administration of a pretest and an enhancement effect would be expected. The major obs...