Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Whether or not information processing differences between severely profoundly retarded (SPR) and normal individuals may be attributed to the inability of severely/profoundly retarded individuals to utilize rehearsal strategies was investigated in this study. The representative ages were chosen based on developmental trends in the utilization of processing strategies. The selected ages were 5-, 7-, 11-, and 15-year-olds for the normal group, and 7-, 11-, and 15-year-olds for the SPR group. A sample of 140 male (60 SPR and 80 normal) were randomly selected from a criteria-selected population. Subjects were randomly assigned within age by intelligence level into experimental (E) and control (C) groups of 10 individuals each. A piece of equipment was designed to measure reaction time (RT), decision time (DT), movement time (MT(,1) and MT(,2)) and response time (TRT). These measures were utilized to indicate the presence, absence, and level of sophistication of rehearsal strategies. The design for the study was age x intelligence level x treatment condition. The results were analyzed in 3 different ways. The first analysis was performed utilizing only data from the normal group. Results indicated that performance improves across ages from 5 years to 15 years. E and C group performances were significantly different at the 5-year-old age level. C group performances approximated the E group performance at the subsequent age levels. The similar performance of the E and C groups at the older age levels was explained by the spontaneous use of rehearsal strategies in the C group. These results verified that information processing strategies such as rehearsal are developmental in nature; i.e., the lack of spontaneous rehearsal by 5-year-olds produced the significantly better performance by the E group when compared to the C group. The second analysis matched SPR and normal individuals by chronological age. Since there were no 5-year-olds in the SPR group, the 5-year-old normal group individuals were omitted from this analysis. Results indicated that some developmental trends were present in the SPR group, since improvement was apparent across ages. SPR and E and C group performances across all ages illustrated that SPR E group performance was consistently superior to performance of SPR C group. The two treatment groups for SPR did not approximate one another at the older age levels which indicated that very little spontaneous use of rehearsal strategies was occurring in the C group. The third analysis regrouped the chronological age matched SPR and normal groups into Developmental Levels. This was accomplished by matching the 5-year-old normal individuals with the 7-year-old SPR individuals, 7-year-old normal individuals with 11-year-old SPR individuals, and 11-year-old normal individuals with the 15-year-old SPR individuals. Results indicated that the performance of the older SPR individuals was closer to the performance of the younger normal individuals. The general conclusions of the study suggested that information processing differences between SPR and normal individuals could be attributed to the inability of the SPR individuals to utilize rehearsal strategies.