Origins of vocabulary variability: A scoping review of infant cognitive processes in relation to word learning and vocabulary development

The role early vocabulary plays in later language development and academic success has been widely acknowledged, and common developmental trajectories are known. Nevertheless, how general cognitive processes support individual trajectories of vocabulary development is not well understood. We explored this issue via a scoping review covering literatures on the relations between nine general cognitive processes (visual processing, visual/spatial attention, attention shifting, sustained attention, visual working memory, novelty detection, object recognition, statistical learning, and declarative memory) and vocabulary development. Processes were selected based on their instantiation in a successful neural-process model of word learning. Auditory processing and discrimination was also reviewed to inform future theory and model development. Systematic database searches were conducted for each process. Papers returned from three databases were screened, reviewed, and the relevant information for each process extracted. While the final number of included papers was limited, we found some evidence of links between nine of the processes and vocabulary development. Evidence of processing differences in children at risk for language impairment was also found for three processes. We discuss the revealed relations and gaps in the literature. We also provide a critical appraisal of the literature and implications for both theory and future work, highlighting the need for integrative longitudinal work and the usefulness of formal models in examining how multiple processes interact to support development.