eutral objects are paired with background scenes that are either of positive, neutral and negative valence (from the IAPS). During each test trial, only a studied or unstudied object is presented, which is first identified (named) in the presence of pixelwise noise (indexing priming); second, recognised from the study phase (after noise removed), using a 4-level confidence rating (from which familiarity can be derived), and third, used to cue recall of the associated scene at study (indexing recollection).
These asymmetrical age effects will be followed up with an examination of the role of regional structural integrity. For example, one explanation for these differential effects of age on different types of memory is that the MTL is more affected by ageing than the occipitotemporal regions associated with visual object priming. Future analyses will also examine the role of emotional processing on memory and the effects of age. A planned fMRI study will expand on structural analyses to examine the potential that prefrontal cortex can play a compensatory role in preserving performance.
Preliminary data from the first 107 CC700 volunteers (Fig bottom,left) confirms a large effect of age on recollection (R=-.68), a smaller effect on recognition (R=-.54) but no significant effect on priming (R=-.12; despite a strong effect of age on overall identification accuracy, R=-.59). This supports previous claims that age differentially affects these different types of memory. Importantly, the effect of age on recollection remained after partialing-out the effect of age on IQ (as indexed by Cattell), suggesting that the memory impairment does not reflect general intellectual decline (Fig bottom, middle). Emotional valence exerted a clear effect on recollection, with greater recall of negative than positive than neutral scenes, and a trend for a less of an age-decline in recall of positive than negative scenes, p=.06, two-tailed (Fig bottom, right).