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FIGURE 8.12 Intelligence endures When Ian Deary and his colleagues retested 80-year-old Scots, using an intelligence test they had taken as 11-year-olds, their scores across seven decades correlated +0.66, as shown here. (Data from Deary et al., 2004.) When 106 survivors were again retested at age 90, the correlation with their age 11 scores was +0.54 (Deary et al., 2013).
(Deary et al., 2013).