A naturalistic home observational approach to children’s language, cognition, and behavior.

Although early life experiences of language and parenting are critical for children's development, large home observation studies of both domains are scarce in the psychological literature, presumably because of their considerable costs to the participants and researchers. Here, we used digital audio-recorders to unobtrusively observe 107 children, aged 2.03 to 3.99 years (M = 2.77, SD = 0.55), and their families over 3 days (M = 15.06 hr per day, SD = 1.87). The recording software estimated the total number of words that a child heard over the course of a day. In addition, we transcribed six 5-min excerpts per family (i.e., 30 min overall) to extract estimates of children's and their parents' lexical diversity, positive and critical parenting, and children's internalizing and externalizing behaviors. We found that home language input (i.e., number of words and lexical diversity) was positively associated with children's cognitive ability and lexical diversity but not with their behaviors. In addition, we observed that home language input varied as much within as between families across days (intraclass correlation = .47). By comparison, parenting predicted children's behavioral outcomes but was not related to their cognitive or lexical ability. Overall, our findings suggest that home language input affects child development in cognition and language, while positive and parenting informs their behavioral development. Furthermore, we demonstrated that digital audio-recordings are useful tools for home observation studies that seek to disentangle the complex relationships between early life home environments and child development.