Starting with laboratory research on the suppression of visualization in reading, this study investigates effects of treatments (reading vs. listening and pictures vs. no pictures, in a 2x2 design) and aptitudes on the learning of verbal and spatial types of content. Approximately 100 fifth grade pupils were given a battery of four ability tests, learning materials dealing with the heart and the flow of blood, and immediate post-tests to assess acquisition of verbal and spatial aspects of the content. The Joreskog LISREL technique was used to analyze the main effects and interactions. It was found that acquisition of spatial content is superior in the audio-visual treatment, and that girls high in general ability perform better when listening than when reading. The results are interpreted in relation to research on visualization suppression and sex differences in lateralization of processing. (Author/PN)