Dissociating recollection precision from success in healthy older adults and mild cognitive impairment

Abstract Background Age‐related variance in episodic memory can be accounted for in part by the retrieval of less precise mnemonic representations, independently of age differences in recollection success. Whether these selective deficits in memory precision are exacerbated in older adults with mild cognitive impairment (MCI) is unknown. Method Healthy older adults and adults with MCI recalled item‐location associations in a circular space. Distance errors between the remembered and true location of each item were fit with a probabilistic mixture model to determine the probability that a given response belonged to a Gaussian distribution with a mean distance error of zero (indicating memory success), or to a uniform distribution comprising the full range of possible responses (indicating memory failure). We defined memory precision as the variability in distance errors during successful retrieval trials (i.e., belonging to the Gaussian component). Result Item recognition and source memory accuracy were reduced in the MCI cohort relative to healthy older adults. By contrast, the precision of successfully retrieved item‐location associations did not differ between the two groups. Conclusion Retrieval success and mnemonic precision represent dissociable sources of variance in memory performance in older age and mild cognitive impairment.