Postural Influences on the Development of Infant Lateralized and Symmetric Hand-Use


  • We would like to acknowledge the infants and parents that participated in our longitudinal study, and whose patience and help made this research possible. Also, we like to thank the many graduate and undergraduate students who helped with the coding of infant data: Richard Jordan, Jessica Hughes, Jessica Irvin, Claudio Ferre, Emily Marcinowski, Justin Varholick, and Jeremy Bailoo. These data were used in partial fulfillment for Iryna Babik's master's thesis. This research was supported by NSF Grant DLS0718045 awarded to George F. Michel.


Within-individual variability is such an apparent characteristic of infant handedness that handedness is believed to consolidate only in childhood. Research showed that manifest handedness is influenced by emerging postural skills (sitting, crawling, and walking). In this investigation, it was proposed that symmetric hand-use (tendency to acquire objects bimanually), rather than lateralized hand-use (the use of one hand more than the other), may be influenced by postural changes. Trajectories of lateralized and symmetric hand-use for object acquisition were examined in 275 infants tested monthly from 6 to 14 months. Multilevel modeling revealed that change in lateralized hand-use is unrelated to developmental transitions in infant posture, whereas the trajectory of symmetric hand-use changes significantly with the development of postural skills.