Abstract
A longitudinal study of an initial sample of 300 men whose ages ranged from 24 to 87 years was carried out using modifications of the logical problems devised by John.Cross-sectional results for all problems showed that, with increasing age, proportions of subjects who solved decreased and uninformative inputs increased.The mean interval between first and second measures was 6.70 years. Longitudinal measures of change showed a mean decline in performance only for the group which was over 70 initially. Much of the decline was attributable to redundant inputs despite the fact that memory demands were minimized and the entire record of input-outcome events was always available. Six-year survival also was related to successful problem-solving performance in the first session.

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