Different object features shape mnemonic discrimination in younger and older adults

The ability to discriminate experiences in memory is an important indicator of cognitive health in older age and a sensitive marker of hippocampal integrity. Measures of mnemonic discrimination, such as the mnemonic similarity task, have the potential to become early diagnostic tools of Alzheimer's dementia. It is thus important to understand how hippocampus-dependent memory functions interact with nonmnemonic processes to determine mnemonic discrimination performance. In this study, we investigate which features contribute to mnemonic discrimination in younger and older age. First, we found in a sample of younger (n = 93, 20-30 years) and older adults (n = 103, 65-82 years) that age impacted performance on the mnemonic similarity task above and beyond the effect of perceptual discrimination of novel 2D configurative objects. Next, in two experiments, we acquired similarity and feature difference ratings for the mnemonic similarity task lures from younger (n = 25 and n = 47, 19-37 years) and older (n = 25 and n = 47, 65-79 years) adults. Using random forest regression and representational similarity analysis, we found that the two groups exhibited unique similarity rating patterns. Finally, enriching our memory data with the feature information, we showed, on the trial level, that mnemonic decisions of older and younger adults are affected by distinct object features. Altogether, these results provide evidence that older adults perceive the differences in lure images distinctively and they may rely on different levels of representations for mnemonic discrimination. (PsycInfo Database Record (c) 2026 APA, all rights reserved).