answering about the present, about themselves 10 years earlier, and about what they expected 10 years hence. They generally reported greater differences between their earlier selves and their present than between their present and future selves.

Nitpick: The comparison was done between predictors and reporters across the same range in age:

Participants were randomly assigned either to the reporter condition (and were asked to complete the measure as they would have completed it 10 years earlier) or the predictor condition (and were asked to complete the measure as they thought they would complete it 10 years hence).

In other words, they compared the 10-year predictions of 18-year-olds to the 10-year reports of 28-year-olds. This is different from (and better than) comparing the 10-year reports and predictions of the same age group.