Infant-directed singing improves infants' social viewing behavior, according to new research

Infant-directed singing improves infants' social viewing behavior, according to new research

In a recently published study in the Proceedings of the National Academy of Sciences Journal, researchers examined the effects of child-directed singing on infants' social visual behavior.

Lernen: Die Musik des kindgerechten Singens fördert das soziale visuelle Verhalten des Säuglings. Bildnachweis: Prostock-Studio/Shutterstock

background

When children are young, caregivers sing to them to calm, soothe, and engage them. In this way, music begins to play a role in social bonding. Infant-directed singing is a universal event that promotes bonds of friendship across cultural boundaries. Singing directed at the child concentrates the child's attention, controls his state of arousal and relieves his suffering.

Singing to babies helps caregivers feel more emotionally connected to their infants and control their own arousal. The process of physiological entrainment is a promising candidate as a potential mechanism through which child-directed singing may promote social behavior.

About studying

In the present study, researchers evaluated whether the rhythm of infant-directed singing influenced infants' visual attention.

Fifty-six two-month-old and 56 six-month-old infants were enrolled in infantile singing. To construct an explicit, unidirectional test of infant entrainment, audiovisual (AV) recordings of infant singing were used. The speed, amplitude and pitch of nursery rhymes such as "Twinkle, Twinkle Little Star" and "Old MacDonald" with naturally occurring variations were performed by amateur singers. AV recordings were sampled at 44.1 kHz while video was recorded at 30 frames per second. A total of nine AV recordings were used, with each recording lasting almost 24 seconds

The rhythmic structure of the song was quantified by categorizing the vowel time spans of the metrically significant syllables in each song, which were referred to as “beats” for convenience. Coding was performed by visualizing each speech spectrogram and waveform and using interactive playback. A total of 227 beats were provided in the nine recordings.

The eye areas were represented as a bitmap in each video frame corresponding to each singing nurse. To determine whether the average eye gaze was timed to match the caregiver's singing rhythmic structure, eye tracking technology (ISCAN) was used to measure infants' visual scanning. Using phase diagrams and Lissajous curves, the team assessed the timing of the infant and caregiver's synchronized responses. The team also examined whether newborn singing rhythms and eye movements were synchronized. The timing associated with eye fixations relative to the timing of metrically strong beats of the song for each age group were also determined.

Results

In infants aged two and six months, infants' increased gaze was temporally tied to the caregiver's singing rhythm. The team also discovered that the phase of each response was strikingly timed to the beat. This was evidenced by the fact that the individual eye gaze reached its highest value within 108 ms after the blow at 58.9% and 32.1% for six-month-old and two-month-old infants, respectively.

The study also showed progression in child development. While infants at two months and six months showed eye gaze responses that were phase locked to the beat, the increase in eye gaze at six months showed much tighter phase locking compared to two months. Similar patterns were observed in the magnitude and shape of peristimulus time histograms (PSTHs). Infants aged two months and six months showed significantly increased eye vision that was temporally linked to the rhythm of the caregiver's singing. However, the magnitude of the increase was significantly higher in the six-month-old infants than in the two-month-old infants.

Furthermore, within-group comparisons and random expected values ​​showed that levels of looking almost doubled after two months, but more than fourfold after six months. These variations supported that rhythmic entrainment for socially adaptive action was detectable at two months of age and before becoming increasingly significant at six months of age, while reflecting motor maturation between two and six months of age.

The results for beats were significantly different from those for high amplitude and high frequency. Instances of high amplitude and high frequency may occur separately from moments of rhythmic significance. However, they are both essential prosodic indicators of communicative emphasis and relate to the rhythm of the stimulus. As a result, they provide related but occasionally separable communicative cues. Neither high amplitude nor high frequency were sufficient to regulate infant gaze at the two-month or six-month age groups when examined as discrete putative drivers of infant gaze.

Overall, the results showed that child-friendly singing was able to direct infants' gaze towards the eyes of their caregivers. This provides a mechanism for child-directed singing to facilitate social interaction throughout development and becomes detectable at two months and more pronounced at six months.

Reference:

• Lense, Miriam D., Shultz, Sarah, Astésano, Corine, Jones, Warren. (2022). Die Musik des kindgerechten Singens fördert das soziale visuelle Verhalten des Säuglings. Proceedings of the National Academy of Sciences. doi: https://doi.org/10.1073/pnas.2116967119 https://www.pnas.org/doi/10.1073/pnas.2116967119

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