The Role of Caregiver Mental Health and Reading Routines on Toddlers’ Heart Rate Responses to Infant-Directed Pitch

Abstract

Infant-directed speech (IDS) is a form of caregiver communication characterized by high frequencies, wide pitch variations, repetition, and short phrases. However, caregiver depression significantly affects the quantity and quality of IDS, resulting in fewer exaggerated intonations, lower pitch, and reduced positive affect in speech. This study investigated the role of caregiver depression on pitch, given findings that IDS-based pitch serves as a communicative signal for children to modulate their attention. Additionally, we examined how caregiver responsiveness and at-home reading routines shapes toddlers’ responses to different pitches in speech. Participants included caregivers and their toddlers (ages 12 to 24 months). At the start of the study, caregivers completed questionnaires assessing depressive symptoms, parental responsiveness, and daily reading routines. Toddlers then watched a video of an actress describing toys using varied pitch contours, followed by a caregiver-led book-reading task. During the study, toddlers wore a heart rate (HR) monitor, with HR measuring attention to pitch. Results revealed that higher caregiver pitch during book reading was associated with increased toddler HR. Caregivers with more depressive symptoms used lower pitch during book reading, and their toddlers had lower HR responses. More responsive caregivers produced higher pitch during book reading. Analyses of at-home routines found that caregivers who read less frequently to their toddlers used higher pitches during the book-reading task, and their toddlers had greater HR differences between trials. These findings underscore the importance of pitch in shaping toddler attention, with caregiver mental health and reading routines being critical in influencing toddlers’ physiological responses to speech.