Two instructional variables, visual illustrations and visual mental imagery, were compared for their influences on learning and cognitive strategies. It was hypothesized, based on dual-code theory, that attempts to combine the two would facilitate learning. In a completely randomized factorial design, treatments consisted of 4 versions of a text-based 2,000-word module on the structure and function of the human heart. Subjects were 112 undergraduates without knowledge in the content area. For the imagery instructed groups, imagery instructions were placed in the treatment booklets in association with the visual illustrations. Results reinforce the importance of relevant visuals to learning and the prominence of imagery use during accretion and retrieval. Main effects were largely produced by visual illustrations, but those who used imagery heavily had higher test scores and were more likely to use imagery in other learning situations compared to those who did not use imagery heavily. Results provide evidence that imagery instructions are valuable for increasing learner interactions with instructional materials, and that they may be especially important when spatial information must be learned. (Contains 28 references.) (SLD)