The effect of a relevant analogy and of subject visualization on the amount of cognitive capacity needed to process unfamiliar information about science was investigated. The dependent measure was reaction time on a secondary task while listening to six tape recorded passages about chemistry and physics in a 2 x 2 x 6 mixed design. The analogy treatment group required less cognitive capacity and the visualization treatment group required more cognitive capacity to process the materials. The analogy results support the theory that analogies make mental processing more efficient by modifying existing cognitive structures prior to processing the new information. The visualization results support a theory that visualizers devote more attention to the material being processed. A general similarity effect of organizing devices is suggested. (Author)