The short-term memory of 24 retarded and 24 nonretarded individuals, aged 10 to 14, under conditions of restricted cognitive strategy use was investigated. An attempt was made to determine whether short-term memory difficulties of persons with mental retardation are caused by deficits in voluntary cognitive strategies, such as the organization and verbal rehearsal of incoming information, or to untrainable structural processes. Three conditions were investigated: short-term visual recall of nouns, short-term auditory recall of consonant triads, and short-term visual recognition for unfamiliar designs in a match-to-sample format. Analyses suggested that both retarded and nonretarded subjects processed auditory and visual information in similar ways. However, subjects with mental retardation demonstrated less efficient information processing, faster than normal stimulus decay, and greater stimulus interference on both recall and recognition items under conditions of restricted cognitive strategies. These findings were interpreted as evidence for structural short-term memory defects of subjects with mental retardation. (Author/JDD)