Cohen, P. A., Ebeling, B. J. & Kulik, J. A. (1981). A meta-analysis of outcome studies of visual-based instruction. Educational Communication & Technology Journal, 29(1), 26-36.

This article describes a statistical integration of findings from 74 studies of visual-based college teaching. In the typical study, students learned slightly more from visual-based instruction than from conventional teaching. In the typical study, visual-based instruction had no special effect on course completion, student attitudes, or the correlation between aptitude and achievement. Students were equally likely to complete visual-based and conventional classes: their attitudes toward the two kinds of classes were very similar; and aptitude played a strong role in determining student achievement in each kind of class.