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

his research investigated adult age differences in recall of a narrative text after younger and older adults 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.