Optimal Linguistic Input for Verb Learning in Young Spanish Learners: Single-word Utterances vs Multi-word Utterances

The acquisition of verbs has long puzzled researchers in language development. Competing hypotheses address whether single-word utterances (SWUs) or multi-word utterances (MWUs) are more effective for early verb learning, with some accounts arguing that encountering words-and verbs in particular-in isolation has benefits (e.g., Brent & Siskind, 2001; Grimm et al., 2019; Lew-Williams et al., 2011; Ninio, 2015, 2016). This study examines the impact of verb uses in SWUs and MWUs on verb acquisition in Spanish-learning children aged 1;6 to 3;0. Longitudinal data from naturalistic interactions across nine CHILDES corpora were analyzed to assess the distribution of SWUs and MWUs, revealing that SWUs are overall less frequent and decrease with age. Study 1 modeled children's actual verb production as a function of input characteristics, showing that verbs appearing more frequently in SWUs were produced by a greater number of children over time-an effect that held across age intervals. In addition, verbs occurring more frequently in MWUs were initially less likely to emerge in the population, although this inhibitory effect diminished with age. Study 2, based on Spanish CDI data, revealed a different pattern: the proportion of verb uses in SWUs or MWUs did not independently predict verb production but instead moderated other effects, with MWUs favoring production at older ages, particularly for more frequent verbs. Thus, despite their relative infrequency in children's input, SWUs appear to play a crucial role in early verb learning, as evidenced by children's production data. CDI results further suggest that MWUs may become increasingly beneficial as children age; however, this finding warrants further investigation. Overall, these results contribute to ongoing discussions about optimal input conditions for early verb acquisition.