This study assessed the effects of varying degrees of elaboration in a prose format using computer-assisted instruction (CAI) with accompanying slides on posttest scores of college age learners. Four instructional treatments were used: control, embedded questions (TR1), computer generated feedback (TR2), and computer generated feedback with a visual rehearsal strategy (TR3). The control group had no elaboration method; for the other three treatments, elaboration was added to the script in increasing degrees. The subjects were 148 undergraduate students enrolled at the Altoona Campus of Penn State University. Materials used included a revised version of an instructional unit on the human heart developed by Dwyer in 1972. The instructional treatments were presented via an interactive video slide system and all subject responses during treatments were restricted to simple keyboard inputs. Each of the four instructional treatments contained the same instructional script, visuals, terminology labels, and arrows. The experimental design was a randomized posttest-only control group design although a 36-question pretest on physiology was used to label each treatment's subjects as high or low prior knowledge. It was concluded that subjects with high prior knowledge will consistently score better than subjects with low prior knowledge regardless of the kind or amount of elaboration, although both groups will benefit about the same from extra elaboration on tests of increasing cognitive difficulty. (12 references) (BBM)