Short-term serial recall in ADDH, normal, and reading-disabled boys.

Short-term retention of verbal items of span and subspan length was examined in hyperactive (ADDH), normal and non-ADDH reading-disabled boys. Performance of ADDH and normal boys did not differ on three measures of verbal serial recall. Thus, it appears that the cognitive deficits of ADDH children cannot be attributed to deficient retention of stimuli. In contrast, reading-disabled (RD) boys performed significantly more poorly than both normal and ADDH boys when required to recall verbal items following "filled" delay intervals in which the children were required to perform a competing verbal activity. The results suggest that verbal encoding of RD children is particularly vulnerable to interference from other verbal stimuli. ADDH and RD children may represent subsamples of children demonstrating academic difficulties, with each group showing a characteristic pattern of cognitive deficits.