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Results of longitudinal studies of intellectual abilities show significant individual variation in maintenance or decrement of such functions throughout adult development. The Life Complexity Inventory (LCI) was designed as a questionnaire to investigate those variables present in the day‐to‐day experience of adults that might relate either to stability or decline of intellectual ability. The LCI was completed by 140 subjects ranging in age from 40–88 years, whose intellectual and personality functioning had been measured in 1956, 1963 and again in 1970. Initial analysis of the data produced eight distinct environmental item clusters. Correlations in the expected direction were found between environmental cluster scores and scores on tests of cognitive function over three time periods. Subject types were obtained from the grouping of individuals by their cluster profiles. Results of the present investigation suggest that those individuals who manifest similar life styles also display similar ability patterns over time.
Gribbin et al. (Tue,) studied this question.