Poster #164 - Relations Between Postural Support and Object Manipulation Skills During the Transition to Independent Sitting

• In Event: 2-055 - Poster Session 06
  In Poster Session: PS 06 Section - Perceptual, Sensory, Motor

Integrative Statement

Reaching and independent sitting are two crucially important milestones in infancy. These skills assist in object manipulation, which facilitates learning about the world and paves the way for later communication skills. Little research has examined how pre- and newly-sitting infants manipulate objects in real time while sitting independently, as they face the challenge of maintaining balance while exploring toys. Infants at heightened risk (HR) for Autism Spectrum Disorders (ASD) experience delays in sitting and exhibit high variability in the development of reaching and object manipulation skills (Nickel et al., 2013; Bhat, Galloway, & Landa, 2012). The present study investigates whether and how two aspects of object manipulation – the ability to grasp an object and transfer it between two hands – change in infants at low (LR) and heightened risk for ASD during the transition to independent sitting, and whether they vary when infants sit with versus without support.
Infants were observed at three sessions in their homes as they transitioned to sitting independently. These sessions include the sit milestone (defined as 30 seconds of sitting without support), as well as sessions two weeks before (pre-sit) and two weeks after (post-sit) the milestone. Participants include 44 infants (24 LR; 20 HR) ranging from 4.5 to 8 months old at first session. Each infant participated in eight 30-second object presentation trials: four while sitting supported by a boppy pillow and four while sitting independently with no external support. In each trial, a toy was presented at midline and the infant reached for and manipulated the toy.
Mean proportion of time spent grasping objects and rate of transferring objects between two hands were calculated for each infant at each session. Preliminary analyses with a subset of LR infants revealed a marginally significant main effect of session on grasping time (p = .061). The proportion of time spent grasping increased linearly across sessions (p = .027; see Figure 1). The main effect of Support was not significant for grasping time. There was another main effect of session on transfer rate (p = .040), with a linear increase over time (p =.054). However, there was a marginally significant Session X Support interaction, such that the linear increase in transfer rate differed as a function of support (p = .093; see Figure 2). Rates of transferring between two hands remained relatively consistent over time in Supported Sitting, but increased sharply in Unsupported Sitting.
The preliminary analyses reveal a trend for both grasping and transferring skills increasing as infants learn to sit and unveil a pattern of greater change in transferring in the unsupported sitting posture. The results provide evidence of the importance of examining object manipulation skills in multiple postural contexts. The study’s future analyses will compare changes in these skills in LR and HR infants. Comparing these groups of infants will not only inform our knowledge of typical motor development, but also support earlier identification of developmental delay and intervention strategies for infants at risk for motor delays.

Authors

• Miranda Michele Mlincek, Carnegie Mellon University and University of Pittsburgh
  Presenting Author

• Emily J Roemer, University of Pittsburgh
  Non-Presenting Author

• Christen E Kraemer, University of Pittsburgh
  Non-Presenting Author

• Jana M Iverson, University of Pittsburgh
  Non-Presenting Author