title: Sequential analysis of postural control resource allocation during a dual task test.
abstract: OBJECTIVE
  To investigate the postural control factors influencing the automatic (reflex-controlled) and attentional (high cortical) factors on dual task.
  
  
  METHODS
  We used a dual task model to examine the attentional factors affecting the control of posture, subjecting test subjects to vibration stimulation, one-leg standing and verbal or nonverbal task trials. Twenty-three young, healthy participants were asked to stand on force plates and their centers of pressure were measured during dual task trials. We acquired 15 seconds of data for each volunteer during six dual task trials involving varying task combinations.
  
  
  RESULTS
  We observed significantly different sway patterns between the early and late phases of dual task trials, which probably reflect the attentional demands. Vibration stimulation perturbed sway more during the early than the late phases; with or without vibration stimulation, the addition of secondary tasks decreased sway in all phases, and greater decreases in sway were observed in the late phases, when subjects were assigned nonverbal tasks. Less sway was observed during the nonverbal task in a sequential study.
  
  
  CONCLUSIONS
  The attentional and automatic factors were analyzed during a sequential study. By controlling the postural control factors, optimal parameters and training methods might be used in clinical applications.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Center for Clinical Research, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Ji Hye
authors.initials: JH
authors.lastname: Hwang
authors.forename: Chang-Hyung
authors.initials: CH
authors.lastname: Lee
authors.forename: Hyun Jung
authors.initials: HJ
authors.lastname: Chang
authors.forename: Dae-Sung
authors.initials: DS
authors.lastname: Park
keywords: Analysis; Attention; Postural balance; Task performance