Auditory short-term memory affects initial but not post-consolidation learning phases: An individual differences study on predictors of word form acquisition

Adults acquire new words, including written and spoken forms across the lifespan. Learning novel words is a dynamic process that progresses from initial familiarization through consolidation towards lexicalization. These processes exhibit substantial interindividual variability. In this study, we leverage this variability to investigate the mechanisms that characterize different learning stages, focusing on the distinct contributions of domain-specific linguistic and domain-general skills.Across three sessions distributed over three weeks, 140 native German participants learned Mandarin Chinese spoken and written (Pinyin) word forms and were tested on the retention of the new knowledge. Additionally, participants completed nine tests assessing linguistic experience, processing speed, auditory and visual short-term memory, and nonverbal reasoning.Structural equation modeling, including latent growth curve analysis, revealed that the acquisition and linking of word forms was primarily shaped by domain-general skills: Processing speed supported word form learning at all stages, while auditory short-term memory supported initial but not later learning. A weaker association to linguistic experience was observed in exploratory network analyses with links between receptive vocabulary at all and spelling at initial stages of learning.These findings highlight that learning is conditioned by how fast and efficient incoming information are processed, and that initial learning is constrained by short-term memory capacity. Consistent with the Complementary Learning Systems account, this points towards distinct stages of learning with effortful and controlled processing at early familiarization stages, and more automatic processing at later consolidation-associated stages. The findings suggest that learners may benefit from tailoring initial input to individual memory capacity.