An internal cognitive variable--mental imagery representation--was studied using a set of three information-processing strategies under external stimulus visual display conditions for various learning levels. The copy strategy provided verbal and visual dual-coding and required formation of a vivid mental image. The relational strategy combined dual-coding with a peg-mnemonic memory procedure involving a set of pre-formed images. The hierarchy strategy combined the processing advantages of the other two strategies but involved encoding new information into a logical taxonomy. Visual stimulus complexity was examined using the visual portion of three slide-tape instructional presentations on the human heart, containing either line drawings, detailed color illustrations, or realistic photographs. Although all three strategies used imagery representations as an information-processing mode, they varied in the amount of cognitive organization imposed on encoded data. The hierarchy strategy resulted in the most effective learning, while the relational strategy was slightly superior to the copy strategy. The simple visual display was the most effective and efficient. (LMM/Author)