The role of memory in the age decline in digit-symbol substitution performance.

Adult age differences in the Digit Symbol Test were investigated in three separate experiments. All experiments incorporated a manipulation of the number of digit-symbol pairs in modified versions of the test forms to determine whether the age differences would be reduced with decreased memory requirements. The results of all three experiments indicated that, as the number of digit-symbol pairs was reduced, the age difference was reduced in absolute terms, but not in relative terms. Older subjects decreased their times by greater absolute amounts, but by the same relative amounts when the number of digit-symbol pairs was decreased from nine to one. Independent results supported the interpretation that memory factors play a very small role in contributing to the age decline in digit-symbol performance.