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The effect of body orientation to gravity on early infant reaching
G J Savelsbergh1, J van der Kamp
1Faculty of Human Movement Sciences, Free University, Amsterdam, The Netherlands.
Insights
Infant reaching development is influenced by body position relative to gravity. Early reaching skills in infants appear when positioned upright, suggesting environmental factors interact with neurological maturation.
Area of Science:
- Developmental Psychology
- Motor Control
- Infant Motor Development
Background:
- Infant reaching is a key developmental milestone.
- Understanding factors influencing reaching development is crucial for developmental research.
- Previous research has primarily focused on age-related maturation.
Purpose of the Study:
- To investigate the impact of body orientation relative to gravity on infant reaching quantity and quality.
- To compare reaching behaviors across different age groups and body positions.
- To explore the interplay between organismic and environmental factors in motor development.
Main Methods:
- Two groups of infants (12–19 weeks and 20–27 weeks) were studied.
- Infants were positioned vertically, reclined, and supine while presented with objects.
- Video analysis quantified reaching quantity (number, duration) and quality (hand posture, arm position, grasp).
Main Results:
- A significant interaction between age and body position was observed for reaching quantity.
- Younger infants (12–19 weeks) in a vertical position demonstrated reaching comparable to older infants in all positions.
- A similar trend for reaching quality was noted, though not statistically significant.
Conclusions:
- Infant reaching development is not solely dependent on central nervous system maturation.
- Environmental context, specifically body orientation with respect to gravity, significantly modulates reaching behaviors.
- Motor development arises from a dynamic interaction between the infant's developing systems and environmental constraints.
Abstract:
The purpose of the study was to examine the effect of body orientation with respect to gravity on infant's reaching quantity and quality. Two groups, 12- to 19-week-old and 20- to 27-week-old infants, were seated in three positions: vertical (90 degrees from horizontal), recline (60 degrees), and supine (0 degrees). Nine balls on a black board were presented. Video recordings were used to measure quantity of reaching (number and duration of reaches) and quality of reaching (open or closed hand, starting position of the arm, and position of touched and grasped balls). On the quantity measure there was a significant age x body position interaction that indicated that the 12- to 19-week-olds showed reaching behavior in the vertical position equal to that of 20- to 27-week-old infants in all positions. A similar tendency, although not significant, was found for the quality measurements. These findings indicate that the development of reaching does not just reflect maturation of the central nervous system, but a changing interaction between organismic and environmental constraints.