Bertenthal, B. I. | bioRxiv Science

bioRxiv2021

Associations between Acoustic Features of Maternal Speech and Infants' Emotion Regulation following a Social Stressor

Caregiver voices may provide cues to mobilize or calm infants. This study examined whether maternal prosody predicted changes in infants biobehavioral state during the Still Face, a stressor in which the mother withdraws and reinstates social engagement. Ninety-four dyads participated in the study (infant age 4-8 months). Infants heart rate and respiratory sinus arrhythmia (measuring cardiac vagal tone) were derived from an electrocardiogram (ECG). Infants behavioral distress was measured by negative vocalizations, facial expressions, and gaze aversion. Mothers vocalizations were measured with spectral analysis and spectro-temporal modulation using a two-dimensional fast Fourier transformation of the audio spectrogram. High values on the maternal prosody composite were associated with decreases in infants heart rate ({beta}=-.26, 95% CI: [-.46, -.05]) and behavioral distress ({beta}=-.20, 95% CI: [-.38, -.02]), and increases in cardiac vagal tone in infants whose vagal tone was low during the stressor (1 SD below mean {beta}=.39, 95% CI: [.06, .73]). High infant heart rate predicted increases in the maternal prosody composite ({beta}=.18, 95% CI: [.03, .33]). These results suggest specific vocal acoustic features of speech that are relevant for regulating infants biobehavioral state and demonstrate mother-infant bi-directional dynamics.

physiology↗

bioRxiv2021

Associations between Infant-Mother Physiological Synchrony and 4- to 6-Month-Old Infants' Emotion Regulation

In this study we assessed whether physiological synchrony between infants and mothers contributes to infants emotion regulation following a mild social stressor. Infants between 4- to 6-months of age and their mothers were tested in the Face-to-Face-Still-Face paradigm, and were assessed for behavioral and physiological self-regulation during and following the stressor. Physiological synchrony was calculated from a continuous measure of respiratory sinus arrhythmia (RSA) enabling us to cross-correlate the infants and mothers RSA responses. Without considering physiological synchrony, the evidence suggested that infants distress followed the prototypical pattern of increasing during the Still Face episode and then decreasing during the Reunion episode. Once physiological synchrony was added to the model, we observed that infants emotion regulation improved if mother-infant synchrony was positive, but not if it was negative. This result was qualified further by whether or not infants suppressed their RSA response during the Still Face episode. In sum, these findings highlight how individual differences in infants physiological responses contribute significantly to their self-regulation abilities.

physiology↗