Iconic memory deficit of mildly mentally retarded individuals.

Ten mildly mentally retarded, 10 equal-CA matched, and 10 equal-MA matched nonretarded subjects were required to recognize both verbal (two-letter words) and nonverbal (polygons) stimuli presented tachistoscopically. A backward visual masking paradigm utilizing both monoptic and dichoptic masking and varying stimulus onset asynchrony (SOA) was employed. The mildly retarded subjects were significantly poorer at the most advantageous (longest) SOAs. The monoptic mask was more effective than was the dichoptic mask, with the three groups demonstrating similar masking functions.