Domain-general processing speed and linguistic experience differentially affect lexical retrieval and structural assembly during language production

Our ability to produce words and sentences relies on lexical retrieval and structural assembly processes, which are supported by domain-general skills. Important topics in current psycholinguistics concern the degree of interaction of both processes and the cognitive costs they incur. Targeting the latter topic, we used an individual-differences approach to test whether the involvement of domain-general skills in language production varies as a function of task complexity. Our participants (n = 169) completed three production tasks that capitalized on lexical retrieval (picture naming) and structural assembly (phrase generation and sentence generation) processes, respectively. In addition, they completed 15 tests measuring linguistic experience, processing speed, working memory, and nonverbal reasoning. Our analysis showed that extensive linguistic experience sped up onset latencies. However, its effect interacted with task, suggesting that it benefited picture naming more than phrase and sentence generation. Critically, this effect was complementary to that of processing speed, which selectively predicted phrase and sentence production but not picture naming. Nonverbal reasoning affected onset latencies in all three tasks, suggesting a non-selective influence. Working memory only had a weak effect. Our findings suggest that while lexical retrieval is primarily supported by linguistic experience, structural assembly is more reliant on processing speed. By integrating multiple predictors, this study provides novel insights into the cognitive architecture underlying language production and highlights the value of a holistic individual-differences approach.