Abstract
Normal aging brings diminished performance on many cognitive tasks. However, some recent studies suggest that visual short-term recognition memory is preserved (Sekuler et al., 2005). To test the boundaries of such preservation, we exploited direct-matching recall, which is sensitive to subtle imperfections in visual memory (Huang & Sekuler, 2010). In this task, subjects adjust one stimulus to match the remembered characteristics of another.
Methods. On each trial, subjects saw two Gabors (each 500 msec) presented in rapid succession. Subjects reproduced the remembered spatial frequency of either the first or the second Gabor. We manipulated the usefulness of attentional selectivity by presenting a cue either before both stimuli (pre-cue) or after (post-cue) in a block design. The cue specified which Gabor, first or second, subjects should match. The presentation of a pre-cue made one upcoming stimulus task-irrelevant, enabling subjects to encode and store only the other stimulus. Subjects were 10 younger (18–24 years, M = 22.1) and 10 older (62–76 years, M = 68.5) adults.
Results. (1) Older subjects' accuracy in memory-based matches was equal to that of the younger subjects. (2) The two groups of subjects showed substantial and equal improvement in accuracy when a pre-cue allowed them to selectively attend to just one of the two stimuli. (3) Subjects in both age groups exhibited a Prototype effect: reproduced frequencies were shifted toward the prototypical value of stimuli seen on previous trials. (4) This Prototype effect gained strength when subjects had to encode and remember two, not one stimulus. This last result is consistent with the hypothesis that the Prototype effect reflects an adaptive augmentation of an imprecise memory.
Short-term recall is preserved with aging, as are the benefits gained from selective visual attention. Both outcomes suggest the importance of compensatory changes in cortical circuitry (McIntosh et al., 1999).
Supported by MH-068404, the Canada Research Chair program and the Canadian Institutes of Health Research.