Resource allocation in on-line reading by younger and older adults.

Younger and older adults read a series of expository passages for immediate recall by self-pacing the presentation sector-by-sector on a computer screen. Regression analysis of sector reading times (RT) was used to estimate the time allocated by individuals to word-level (i.e., syllable length and mean word frequency), text-level (i.e., number of propositions, number of new concepts introduced, and total Yngve depth), and discourse-level (i.e., serial position) features. Age differences were found in the pattern of reading time allocation that engendered high levels of recall. Specifically, younger adults who achieved high recall were more responsive to word frequency and the introduction of new concepts. By contrast, high recall among the old was related to a greater degree of on-line contextual facilitation (i.e., a steeper serial position effect). These data suggest that there is an age difference in how the allocation of resources at encoding optimizes subsequent memory performance.