How do high frequency words help language acquisition?

Learners can extract transitional information from speech and use it to infer word boundaries and linguistic regularities. Critically, studies suggest that statistical language learning may benefit from the presence of high-frequency marker words (Bortfeld et al., 2005) that may act as anchors around which speech segmentation can occur, while also assisting with grammatical categorisation (Monaghan & Christiansen, 2010). To address these claims, we familiarised adults with a continuous stream of language comprising sequences of 8 bisyllabic target words, and compared learning to the same language but with high-frequency monosyllabic marker words preceding target words, and distinguishing them into two distributionally-defined categories. Participants completed a 2AFC testof segmentation, and a similarity judgement categorisation test containing word-pairs from the same versus different categories. We then tested transfer to a word-action/object learning task, where target word categories were either consistent or inconsistent with the action/object distinction. Participants segmented the speech stream better than chance, but only the marker word condition resulted in effective categorisation for the similarity judgement task. The advantage of marker words extended to the early stages of the word-learning task. Findings indicate that high-frequency marker words may assist grammatical categorisation even when they are not required for speech segmentation