Poster #159 - Holding Objects: Developmentally Changing Attractor Dynamics in Late Infancy

• In Event: 3-003 - Poster Session 09
  In Poster Session: PS 09 Section - Perceptual, Sensory, Motor

Integrative Statement

Human infants interact with the environment through a growing and changing body and their manual actions provide new opportunities for exploration and learning. Many contemporary theories of motor development emphasize sources of order in movement over developmental time. In infants, the first two years of life is a period of development with dramatic anatomical changes resulting in new opportunities for action. Such developmental change provides a window into understanding the developmental trajectory of manual action dynamics. In the current study, a dynamical systems approach was used to quantify and characterize the early motor development of limb effectors during bouts of manual activity. We introduce a novel analytical protocol for estimating properties of attractor regions (Figure 1). We apply this new analysis to a longitudinal corpus of manual actions during sessions of toy play across the first two years of life (6,996 manual actions from 43 unique infants across a total of 131 sessions). We demonstrate developmental change in the attractor dynamics of the dominant hand, consistent with the emergence of flexible motor behavior (Figure 2). We also demonstrate that the act of holding itself occurs within the attractor region of the limb’s movement, a region characterized by low velocity and low speed. Our study is the first – to our knowledge – to index the development of flexibility of manual action in a natural free flowing context throughout the first two years of life. By showing that the dominant hand becomes more flexible across development – as observed by increased attractor region size – we add more insight into the developmental trajectory of the manual action system. Our study also contributes a new method for reducing the dimensionality of behavior down to a phase portrait and then quantifying properties such as the size of an attractor region or the time inside or outside of an attractor region. This study, therefore, serves as a first step in quantitatively defining the development and function of attractor dynamics in manual action.

Authors

• Jeremy Isaac Borjon, Indiana University
  Presenting Author

• Drew Abney, Indiana University
  Non-Presenting Author

• Linda B Smith, Indiana University
  Non-Presenting Author

• Chen Yu, Indiana University
  Non-Presenting Author