Individual Differences in Global Cognition Modulate the Effect of Motor-Relatedness on Object Naming in Healthy Older Adults.

Lexical retrieval difficulty is a common daily complaint among older adults. Recent evidence suggests that older adults name motor-related nouns (e.g., knife) more accurately than non-motor nouns (e.g., steak). However, it remains unclear whether this motor-relatedness effect can reduce older adults' object naming latency (a potentially more sensitive measure of word retrieval than accuracy) and how it may be modulated by individual differences (e.g., age and global cognition). Therefore, we recruited a large number of older adults to complete a Chinese version of the Montreal Cognitive Assessment (MoCA) and a timed picture-naming task, and we explored the two remaining issues with data from 76 community-dwelling older adults (65-81 years old), excluding participants with possible AD. Linear mixed-effects analysis revealed a main effect of motor-relatedness on naming latency in older adults and a significant interaction with the MoCA score after controlling for a number of stimulus-related factors (i.e., age of acquisition, familiarity, name agreement, and visual complexity) and participant-related factors (i.e., gender and education) as covariates, but age showed neither a main effect nor a significant interaction with motor-relatedness. Further simple slope analysis showed that older adults were faster at naming objects with high motor-relatedness and that older adults with low MoCA scores benefited more from the motor-relatedness effect. These findings suggest that motor-relatedness may compensate for the normal course of cognitive ageing in older adults. Implications for the motor-relatedness effect were discussed.