Short-term memory and equivalence judgments in normal and retarded readers.

Matched groups of normal and disabled readers were required to perform same/different judgments in which the interval between standard and comparison stimuli was either 0, 1, or 6 sec. Standard and comparison stimuli were either the same, different in element order, or different in actual elements present. Retarded readers performed as well as controls on same tasks in all 3 delay conditions. Difference tasks discriminated retarded readers on 1- and 6-sec conditions, but not on 0-sec conditions. Differences in order and gross element distinguished retarded from adequate readers equally well. The results are interpreted to indicate a deficit in short-term memory in retarded readers, but only for tasks requiring a difference judgment.