This dissertation presents the results of an investigation of visual mental imagery as a strategy hypothesized to increase the amount of interaction with content material and therefore the level of information processing and acquisition, and to assist information retrieval on posttests. Four treatments were used in a crossed, randomized two by two factorial design. The two independent variables were imagery instructions embedded in the text and visual illustrations related to the text. Instructional materials used were four versions of a 2,000-word script on the human heart (F. M. Dwyer, 1978). Dependent measures taken were a drawing test and three multiple-choice tests of 20 questions each, designed to measure factual learning, identification of parts, and comprehension learning. A post-treatment questionnaire assessed the subjects' perceptions of the effect of the imagery instructions and their use of imagery. Significant differences were noted on the ANOVA tests for many of the dependent measures, and both factors produced significant results on the drawing posttest. The group with the treatment containing both visuals and imagery consistently had the highest means for all test measures, while the group having text plus imagery had the lowest multiple-choice test score means of all groups. Among this sample, imagery was found to be a prominent cognitive process for the retention of information in all learning situations. Although it is not used exclusively to retain information, there is some evidence that imagery instructions interact with instructional visuals when embedded in text. Appendices contain the informed consent form and instructions to the subjects, the post-treatment questionnaire, pilot study data, experimental materials, criterion-referenced posttests, reliability coefficients, and the cell means of the dependent measures. (117 references) (Author/DB)