“…By requiring that infants look at, or even point to, something to demonstrate understanding, standard behavioral measures may be insufficient to capture infants' emerging representations of words that may not have direct visual associates (Wojcik et al, under review). When presenting only two-dimensional images, or even videos (e.g., Syrnyk & Meints, 2017) of intended referents, highly-controlled lab-based experiments generally lack the richness and diversity of infants' real-world language environments (Nastase et al, 2020;Reuter et al, 2021;Tamis-LeMonda et al, 2017) and may therefore eliminate connections to socio-emotional, pragmatic, or contextual information and other cues that are useful for word recognition. The low-dimensionality of common lab-based measures may be especially problematic for everyday words, which by their routine-based nature may be tied to less-visible situational factors, such as affective state (e.g., uh-oh is likely to be produced under more dramatic circumstances than many concrete nouns, Ponari et al, 2018) or event timing (e.g., uh-oh is likely to coincide with salient event transitions, such as when the child falls, hi is likely to occur when a new interaction begins, which creates opportunities for learning during moments of heightened attention, Kosie & Baldwin, 2019) Furthermore, early word knowledge may be highly idiosyncratic, as evidenced by the cross-household variability observed in our study, making it difficult to capture early comprehension with one standard set of stimuli.…”