Changes in lateral differentiation of head posture in the human neonate
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Newborn infants show a developmental shift in head turning. Infants over 12 hours old consistently turn their heads right, suggesting early lateralization in responsiveness.
Area of Science:
- Developmental psychology
- Infant motor development
- Neuroscience
Background:
- Infants exhibit lateral differences in responsiveness to stimuli.
- Asymmetrical head postures are common in newborns.
- The interplay between head posture and sensory responsiveness is not fully understood.
Purpose of the Study:
- To investigate developmental changes in the relationship between lateral responsiveness and asymmetrical head postures in infants.
- To determine the age at which consistent head turning preference emerges.
Main Methods:
- Observed head turning in 70 infants aged 0-72 hours.
- Utilized a procedure to minimize lateral differences in response to stimulation.
- Compared head turning in infants with and without interference with natural lateral sensitivity.
Main Results:
- Infants older than 12 hours showed a significant preference for rightward head turns, even after midline positioning.
- Younger infants (0-12 hours) did not exhibit a significant head turning preference when responsiveness was normalized.
- Infants aged 0-12 hours without interference also displayed a rightward head turn preference.
Conclusions:
- A developmental change occurs in the relationship between lateral responsiveness and head posture.
- Rightward head turning preference emerges after 12 hours of age.
- This suggests a reciprocal relationship between asymmetric head position and lateralized sensory sensitivity in early development.
Abstract:
Developmental changes in the relationship between lateral differences in responsiveness and the assumption of asymmetrical head postures were examined. The head turning of 70 infants ranging in age from 0-72 hr was observed following a procedure (maintenance of the head in a midline position) known to reduce or eliminate lateral differences in the infant's response to stimulation. Even following this procedure infants older than 12 hr made significantly more right than left head turns whereas younger infants exhibited no such difference. When lateral differences in sensitivity were not interfered with in 0 to 12 hr old infants (n=20) they, kile the older infants, made significantly more right than left turns. These results are discussed in terms of possible developmental consequences of a reciprocity between asymmetric head position and lateral differences in sensitivity.