Where in an ordered sequence of variables do independent age-related effects occur?

Abstract

A series of regression analyses was conducted to determine which variables in an ordered sequence had significant age-related effects after control of the immediately preceding variable in the sequence. Independent age-related effects in these types of analyses are particularly interesting because they represent age-related influences that are not mediated through earlier variables. A total of 56 analyses are reported with ordered variables representing: (a) successive trials or sessions in learning; (b) progressively more intervening events during the retention interval of a memory task; (c) successively longer stimulus presentation durations; and (d) increased processing complexity. In most of the analyses a very large proportion of the age-related effects on later variables was found to be mediated through earlier variables in the sequence.