Executive Function Predicts Older Adults' Lure Discrimination Difficulties on the Mnemonic Similarity Task

Objectives Older adults often have difficulty remembering the details of recently encountered objects. We previously found this with the Mnemonic Similarity Task (MST). Surprisingly, the older adults' MST Lure Discrimination Index (LDI) was significantly correlated with visual acuity but not with memory or executive function. Here we ran a replication with new, larger samples of young (N = 45) and older adults (N = 70). We then combined the original and replication older adult samples (N = 108) to critically examine the relative contributions of visual acuity, memory, and executive function composite scores to LDI performance using dominance analysis. This provided, to our knowledge, the first direct statistical comparison of all 3 of these factors and their interactions on LDI. Methods Participants completed the MST and a battery assessing visual acuity, memory, and executive function. We examined age group differences on MST performance in the new (i.e., replication) young and older adult samples and performed multiple regression and dominance analysis on the combined older adult sample. Results Consistent with previous findings, the older adults showed significantly poorer LDI but preserved item recognition. LDI was significantly correlated with both memory and executive function but not with visual acuity. In the combined older adult sample, all 3 composites predicted LDI, but dominance analysis indicated that executive function was the most important predictor. Discussion Older adults' MST LDI difficulty may be predicted by their executive function and visual acuity. These factors should be considered when interpreting older adults' MST performance.