The study attempted to determine whether the failure of Down Syndrome (DS) individuals to show the modality effect (the tendency to show better short-term memory for brief sequences of auditory rather than visual information) is due to the verbal-expressive demands of oral responding in memory tasks. DS, nonretarded (NR) and MR (non-DS mentally retarded) Ss (N=33) listened to or looked at increasingly-long sequences of single digits and attempted to recall them either orally or manually. Analyses suggested that (1) manual responding failed to enhance auditory recall in either DS or any other Ss; (2) difficulity in recalling auditory stimuli was greatest for DS mentally retarded Ss; and (3) DS auditory difficulty was most apparent in the recall of order information. Findings suggested that the adverse consequences of mental retardation were most apparent in the recall of order information, and that this recall difficulty was greater for DS Ss. (Author/CL)