The effect of presentation time on learning under varying mediation instructions demonstrated a time-dependent difference in the facilitating effect of imagery generation or sentence generation instructions. Subjects were junior high school students working in a paired associate task with concrete nouns. Both cognitive strategies were more effective than none or a repetition technique for this learning task. The study suggests that shorter time intervals should be investigated to establish minimum times for verbal and imaginal processing. Instruction in the use of varying cognitive strategies may prove to be a useful teaching tool at all levels of education. (Author)