Short-Term Memory in Normals and Retardates as a Function of Stimulus Intensity and Recall Interval: A Test of Ellis's st Theory

Two predictions derived from Ellis's (1963) stimulus trace (st) deficit theory were tested with equal CA (approximately 9 years) normal and retarded children in a digit recall task. Length of recall interval (0 vs 8 sec.) and intensity level of the aurally presented items (55 vs 90 db) were varied factorially. All of the material was taped and received by subjects through earphones. Contrary to Ellis's theoretical predictions, the two IQ groups demonstrated parallel retention functions, and the performance of neither group was affected by the intensity manipulation.