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Updated: Aug 26, 2025
An Instrumented Pull Test to Characterize Postural Responses
Published on: April 6, 2019
The Pull-to-Sit Task: Examining Infant Postural Development in Autism Spectrum Disorder
Jessica Bradshaw1, Dexin Shi1, Alexis Federico1
1Department of Psychology, University of South Carolina, Columbia, SC.
Insights
Early head control in infants, specifically a persistent head lag, may indicate later social and language challenges, including autism spectrum disorder (ASD). This highlights the link between early motor skills and developmental outcomes.
Area of Science:
- Neurodevelopmental Pediatrics
- Autism Spectrum Disorder Research
- Infant Motor Development
Background:
- Early detection of autism spectrum disorder (ASD) is crucial for timely intervention.
- Postural and head control assessed via the pull-to-sit task are early developmental milestones.
- Understanding the predictive value of early motor skills can inform diagnostic approaches.
Purpose of the Study:
- To investigate the relationship between early pull-to-sit task performance trajectories and later autism diagnosis.
- To determine if early postural and head control predict developmental outcomes at 24 months.
- To identify potential early indicators of social and language vulnerabilities.
Main Methods:
- Prospective longitudinal study of 100 infants with varying familial likelihood of ASD.
- Monthly assessment of pull-to-sit task performance from 1 to 6 months of age.
- Developmental and diagnostic evaluations at 24 months, with examiners masked to group assignment.
- Latent growth curve modeling to analyze trajectories and predictive relationships.
Main Results:
- No significant differences in pull-to-sit trajectories between infants later diagnosed with ASD and typically developing infants.
- Infants with ASD were more likely to exhibit head lag by 4 months.
- Early pull-to-sit trajectories predicted social and speech skills at 24 months.
Conclusions:
- Early pull-to-sit skills are linked to later social and language development.
- Atypical postural development and persistent head lag may signal early social and language vulnerabilities.
- These findings suggest potential for early identification of ASD and related developmental risks.
Objective:
To evaluate the predictive relationship between early trajectories of postural and head control during a pull-to-sit task and later autism diagnostic and developmental outcomes.
Study Design:
Using a prospective longitudinal design, postural skills of 100 infants at elevated and low familial likelihood of autism spectrum disorder (ASD) were evaluated using a pull-to-sit task monthly from age 1 month to 6 months. At age 24 months, infants were seen for a developmental and diagnostic evaluation completed by examiners masked to participant group. Latent growth curve models were used to compare early trajectories of pull-to-sit performance in infants later diagnosed with ASD and typically developing infants and to predict developmental outcomes.
Results:
Pull-to-sit trajectories did not differ in infants with an elevated likelihood of ASD or infants with ASD compared with low-likelihood and typically developing infants, but infants with ASD were more likely to exhibit a head lag by age 4 months. In addition, pull-to-sit trajectories were predictive of social and speech skills 2 years later.
Conclusions:
These findings highlight the link between very early pull-to-sit skills and later social and language outcomes. Atypical postural development and persistent presence of head lag may be important early indicators of social and language vulnerabilities, including ASD.
