The respective contribution of cognitive control and working memory to semantic and subjective organization in aging.

Abstract

Organizing information is beneficial to episodic memory performance. Among several possible organizational strategies, two consist of organizing the information in semantic clusters (semantic organization) or self-organizing the information based on new associations that do not exist in semantic memory (subjective organization). Here, we investigated in a single study how these two organizational behaviors were underlined by different controlled processes and whether these relations were subjected to age-related differences. We tested 123 younger adults (n = 63) and older adults (n = 60) on two episodic memory tasks, one where the words were organizable and another where the words were not organizable, allowing for semantic and subjective organization, respectively. Additionally, participants were tested on three cognitive control tasks (Wisconsin Card Sorting Test, Stroop Test and Trail Making Test) and three working memory tasks (Backward Digit Span, Alpha Span and N-back test). Results revealed well-established age-related differences in terms of recall performance and organizational strategy implementation. More importantly, we found evidence that the different cognitive tests statistically yielded two different latent factors, a cognitive control factor and a working memory factor. Based on this dissociation, we found that only cognitive control contributed to semantic organization in all age groups whereas only working memory contributed to subjective organization, also in all age groups. These results shed new lights on our understanding of how controlled processes differently contribute to organizational behaviors in episodic memory. Public Significance StatementThis article shows that cognitive control and working memory are dissociable processes based on the cognitive tests used here. Importantly, it was found that these processes contribute differently to different mnemonic organization strategies. Cognitive control contributes more to the organization of words based on their semantic categories, whereas working memory contributes more to the self-organization of unrelated words. These findings appear to be found similarly in younger and older adults.