Role Differentiated Bimanual Manipulation in Infancy

This dissertation utilizes data from lab-based free play and natural play in the home setting to expand upon the contextual factors that influence fine motor skills, specifically role differentiated bimanual manipulation (RDBM). Study 1 consisted of free play data collected in a lab-based setting and furthers the understanding of how complex bimanual actions emerge during play where infants can adopt a wide range of postures and interact with a variety of objects. During this study, 78 13- and 24-month-old infants (39 of each age) were able to play with objects of various sizes and weights in whichever posture they chose. While infants frequently engaged in object interactions, RDBM made up a small percentage of the interactions. Although infants engaged with various toy sizes in multiple postures, they preferred light weight toys and being in a seated position. The 13-month-old infants preferred small toys while the 24-month-old infants engaged with medium and large toys. Study 2 and 3 of this dissertation documented RDBM in the home setting during a one-hour-long observation of everyday activity between 107 caregiver and infant pairs (Study 2: 17 13-month-olds; 17 23-month-olds; Study 3: 13 9-month-olds; 20 12-, 15-, and 18-month-olds), allowing us to capture a wider range of object characteristics as well as caregiver interactions for RDBM. Overall, RDBM made up less than a quarter of object interactions for infants of all ages. Furthermore, infants preferred to engage in RDBM with toys instead of non-toys (household objects). Additionally, infants preferred to be seated while performing RDBM, but infants with advanced locomotor abilities were able to incorporate RDBM more often while standing. Altogether, these findings indicate that while infants display RDBM with a variety of objects and postures, they do have specific preferences, suggesting that contextual factors play a role in the emergence and development of complex bimanual actions, providing information on how to encourage and promote RDBM during play.