Domain-general skills predict individual differences in linguistic knowledge and spontaneous language use

The present study investigated predictors of individual differences in linguistic knowledge and spontaneous language use in adults. Specifically, we examined the role of domain-general cognitive abilities—working memory, nonverbal reasoning, and processing speed—alongside implicit motivational factors, including achievement, power, and affiliation motives and activity inhibition. Linguistic knowledge was assessed through multiple tests covering receptive and productive vocabulary, grammar, spelling, and comprehension of fixed expressions, whereas language use was examined through participants’ written narratives in the Picture Story Exercise (PSE), analyzed with the Linguistic Inquiry and Word Count (LIWC) framework. Network and path analyses revealed that auditory working memory positively predicted linguistic knowledge and analytic language use, highlighting its role in the sequential organization and consolidation of verbal material. Visual working memory was unrelated to knowledge but predicted more authentic language use, suggesting a link to imagery-based and self-referential expression. Nonverbal reasoning supported knowledge but was negatively related to authenticity, indicating a trade-off between systematic abstraction and spontaneity. Processing speed, while crucial in early language development, did not predict knowledge in adults and was negatively associated with narrative word count, suggesting that efficiency may reduce elaboration in spontaneous production. Contrary to our predictions, implicit motives and activity inhibition were unrelated to both linguistic knowledge and language use. Together, these findings underscore how distinct domain-general abilities shape static linguistic knowledge and dynamic language use, highlighting the need for integrative models of adult language skills.