Differential Effects of Intellectual Level on Age Related Declines in Intelligence -- Tonya L. Bennett, Student, School of Psychology and Henry V. Soper, Faculty, School of Psychology
Though intellectual declines with age have long been acknowledged, the question of interest here is the differential loss of functioning over the years among those of above and below average intelligence. Methods: We decided to compare the performances of the different age groups to those just entering adulthood at age 16. We used a current adult intellectual assessment scale, the Wechsler Adult Intelligence Scale-IV. Scores which would result in average (index = 100), superior (120) and low average (80) for each age were compared using the normative data for 16-year-olds. Results: Full Scale scores for the lower two groups start to drop after age 45, and by age 80 average functioning is equivalent to the borderline or lower range for 16-year-olds. The Full Scale IQ (FSIQ) scores for the superior group actually rise on the order of 10 points and remain above the initial score to about age 55, whence a slow decline begins. Vocabulary score held well for all groups, and verbal comprehension held almost as well. Perceptual reasoning showed declines after mid-adulthood. Working memory, surprisingly, held well into the 70s for each group, but the expected drop in processing speed after age 45 was observed. Conclusions: This study showed the expected and previously observed intellectual decline of those of average and below intelligence, but the results indicate that those who start in the superior range hold overall ability and actually improve in FSIQ scores over the working years.