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Lateral biases and fluctuations in infants' spontaneous arm movements and reaching
1Department of Health, Kinesiology, and Leisure Studies, Purdue University, West Lafayette, IN 47907, USA.
Insights
Infant hand preference development shows lateral shifts in both reaching and spontaneous movements. These early motor system reorganizations predict later-established right-handedness in young children.
Area of Science:
- Developmental psychology
- Motor control
- Neuroscience
Background:
- Hand preference development in infants typically involves lateral fluctuations.
- Previous research focused on reaching movements, leaving spontaneous movements less explored.
Purpose of the Study:
- To investigate lateral fluctuations in infants' spontaneous, nonreaching movements.
- To determine if these fluctuations mirror those seen in reaching movements.
- To correlate early movement patterns with later-established hand preference.
Main Methods:
- Longitudinal kinematic data collection of reaching and nonreaching movements in 4 infants during their first year.
- Assessment of hand preference direction in the fourth year of life.
Main Results:
- Spontaneous, nonreaching movements exhibited lateral biases with shifts similar to reaching movements.
- All infants showed a transient period of right-handedness in their first year.
- This early right-handedness corresponded with their established hand preference at age 3.
Conclusions:
- Lateral shifts in infant hand preference development are not limited to reaching but also occur in spontaneous movements.
- These early motor system reorganizations, linked to developmental milestones like sitting and crawling, influence the trajectory of hand preference.
- The findings suggest a connection between early motor system plasticity and the emergence of stable hand preference.
Abstract:
The development of hand preference in infant reaching is marked by several lateral fluctuations. This study investigated whether similar lateral fluctuations were present in infants' spontaneous, nonreaching, and freely performed movements. We collected reaching and nonreaching movements kinematics in 4 infants that we followed longitudinally during their 1st year. In their 4th year, we assessed the direction of their hand preference. We found that lateral biases in spontaneous, nonreaching movements in the 1st year showed several shifts that were similar to those observed in reaching. Despite these shifts, all 4 infants traversed a short period of right-handedness. This right-handedness matched the direction of their hand preference at 3 years of age. We propose that shifts in the development of hand preference in the 1st year are linked to successive reorganizations of the motor system. These reorganizations take place as infants learn to sit, crawl, and walk.