Speed of information processing and working memory as mediators of age differences in prose recall

Abstract

his research investigated adult age differences in recall of a narrative text after younger and older adults T engaged in the same, low-effort encoding strategy. Task-specific and task-independent measures of speed of information processing and a measure of working memory capacity were examined as potential mediators of age differences in prose memory. The effect of recall mode (oral vs. written) on prose recall was also investigated. Thirty-six younger adults (mean age = 21 years) and 36 older adults (mean age = 72 years) participated. They were required to read a story aloud once and then provide either oral or written recall of the text. Speed of processing was assessed by scores on reading time, articulation speed, and the Digit Symbol Substitution Test (DSST; Wechsler, 1981). Working memory capacity was assessed by a backward word-span measure. As expected, younger adults recalled more propositions from the text than did older adults, but there was no effect of recall mode on prose recall. Younger adults were faster on all speed-of-processing measures and had higher backward word-span scores than did older adults. Unexpectedly, reading time and articulation speed did not predict prose recall although, after controlling for reading time, age and DSST contributed more to the variance than when reading time was not controlled. Speed of processing, measured by the DSST, and working memory capacity made independent contributions to, and mediated most of, the age differences in prose recall.

The Executive Decline Hypothesis of Cognitive Aging: Do Executive Deficits Qualify as Differential Deficits and Do They Mediate Age-Related Memory Decline?

“…Recall and recognition also correlate more highly with the DSST than with the other subtests. Due to this pattern of correlations between age, recall, recognition, and the DSST, and given the reliable findings that DSST performance has been found to be a mediator of age-related variance in memory (e.g., Bryan & Luszcz, 1996, 1999Salthouse, 1991), it was decided to investigate the relative contributions of executive function and DSST performance to age-related decline in memory. Once again, hierarchical multiple regressions were employed to examine these predictors of memory and the results appear in Table 8.…”

Toward Understanding Age-Related Memory Loss in Late Adulthood

“…These should enable evaluation of how the mechanisms interact or if they make independent contributions to remembering. Typically experimental and correlational research proceeds in parallel, although the utility of hybrid approaches is substantial [18,20,22]. The challenging and exciting question of whether one mechanism or resource may be more basic or primitive to cognition necessitates that they be examined concurrently in the same individuals, across a range of different memory tasks.…”

“…Many studies have found that speed of processing is an important mediator of age-related memory decline [11,[17][18][19], including memory for prose [19][20][21][22][23] and incidental memory [1]. It appears that the role of speed of processing in remembering may be particularly important during rehearsal or encoding [18,24], as Salthouse [14] originally theorised.…”

“…Both Park et al [11] and Bryan and Luszcz [18,20] adopted a two-factor resource account in which both speed and working memory were postulated as potential mediators of memory performance across the adult life-span. Park and associates examined performance on free recall, cued recall and spatial memory, as these tasks differ in resource requirements, with free recall being the most, and spatial memory the least, resource intensive.…”

“…Bryan and Luszcz [18,20] examined the mediation of age differences by speed and working memory for free recall of word lists and text under conditions where encoding was controlled. In both studies speed emerged as the principle mediator of age-related variance.…”