Mothers speak less to infants during detected real‐world phone use

The current study is the first to document the real‐time association between phone use and speech to infants in extended real‐world interactions. N= 16 predominantly White (75%) mother–infant dyads (infants aged M = 4.1 months, SD = 2.3; 63% female) shared 16,673 min of synchronized real‐world phone use and Language Environment Analysis audio data over the course of 1 week (collected 2017–2020) for our analyses. Maternal phone use was associated with a 16% decrease in infants' speech input, with shorter intervals of phone use (1–2 min) associated with a greater 26% decrease in speech input relative to longer periods. This work highlights the value of multimodal sensing to access dynamic, within‐person, and context‐specific predictors of speech to infants in real‐world settings.