FIGURE 8.13 Intelligence endures When Ian Deary and his colleagues (2004) retested 80-year-old Scots, using an intelligence test they had taken as 11-year-olds, their scores across seven decades correlated +.66. (When 207 survivors were again retested at age 87, the correlation with their age 11 scores was +.51 [Gow et al., 2011].)