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Updated: Oct 27, 2025
Quantifying Learning in Young Infants: Tracking Leg Actions During a Discovery-learning Task
Published on: June 1, 2015
Infants born preterm and infants born full-term generate more selective leg joint movement during the scaffolded
Jeong Ah Kim1, Linda Fetters1, Masayoshi Kubo2
1Division of Biokinesiology and Physical Therapy, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, USA.
Insights
Infants born very preterm (PT) showed improved selective leg movements in a mobile task. A scaffolded task encouraged PT infants to move hips and knees more selectively, aiding potential walking development.
Area of Science:
- Developmental neuroscience
- Pediatric motor control
- Rehabilitation science
Background:
- Infants born very preterm (PT) face higher risks for cerebral palsy, impacting motor skills.
- Spastic cerebral palsy in children often involves impaired selective leg joint movement, leading to lifelong walking difficulties.
Purpose of the Study:
- To determine if infants born PT exhibit more selective hip-knee joint movement during a scaffolded mobile task.
- To assess if varying virtual threshold heights influence selective leg movement in PT and full-term (FT) infants.
Main Methods:
- A scaffolded mobile task was used with 4-month corrected age PT and FT infants over 2-3 days.
- Infants were required to lift legs over virtual thresholds of low, middle, and high heights.
- Selective hip-knee movement was compared between baseline spontaneous kicking and task performance.
Main Results:
- Both FT and PT infants learned the task, demonstrating increased selective hip-knee movement.
- FT infants showed selectivity at all threshold heights on their learning day.
- PT infants exhibited selective movement primarily at the middle and high threshold heights.
Conclusions:
- The scaffolded mobile task is effective in promoting selective hip-knee joint movement in infants.
- Higher thresholds in the task appear more effective in encouraging selective movement in infants born PT.
- Findings suggest potential for early intervention strategies to improve motor outcomes in PT infants.
Abstract:
Infants born very preterm (PT), prior to 32 weeks gestation, are at increased risk of developing cerebral palsy. Children with spastic cerebral palsy have impaired selective leg joint movement, which contributes to lifelong walking limitations. We investigated whether infants born PT generated more selective hip-knee joint movement (e.g., hip flexes as knee extends) while participating in a scaffolded mobile task. Infants born PT and infants born full-term (FT) at 4 months corrected age participated in a scaffolded mobile task for 2-3 consecutive days. The scaffolded mobile task required infants to raise their legs vertically over a virtual threshold. Three threshold heights (low, middle, and high) were used to test whether the middle and high heights encourage infants to move their legs more selectively. Fifteen infants born FT learned the task and showed more selective hip-knee movement at each of the three threshold heights on the day that they learned, compared with their baseline spontaneous kicking. Thirteen infants born PT learned the task and showed more selective hip-knee movement on their learning day, but only when the middle and high thresholds were used. The results show that the scaffolded mobile task effectively encouraged infants to generate more selective hip-knee joint movement.
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