| The purpose of this thesis was to investigate how well healthy children and healthy young adults can track (with body sway and gaze) visual target cues that differ in degree of complexity (periodic, chaotic, and noise) during a voluntary, visually guided sway task in the anterior-posterior (A/P) and medio-lateral (M/L) directions. 22 healthy children (7.7 +/-1.9) and 13 healthy young-adults (23.8 +/-2.9) performed six, two-minute trials. The variables of this study examined the coupling between the participants posture (center of pressure) and the stimulus, as well as the gaze and the stimulus. Coupling was quantified using three different variables: cross-approximate entropy, cross-correlation, and coherence. Results showed that children, as young as five years old, could entrain their gaze and posture to stimuli of increasing complexity. The results of the present study are in agreement with previous research that healthy young adults can track, with their gaze and posture, complex motion of a visual stimulus (Hatzitaki et. al, 2015; Sotirakis et. al, 2016). It was also found that children do not couple as strongly as healthy young adults. Based on the results, reduced coupling is a function of stimulus complexity for both stimulus_COP and stimulus_Gaze on most trials, with the exception of the younger children who had higher coupling with the chaotic stimulus. Both stimulus_COP and stimulus_Gaze coupling are affected with age, in that as we age, coupling becomes stronger. Finally, we attribute the weaker coupling in young children to less neuromuscular development, and also differences in sensory prioritization. |
