Objective : To investigate postural control factors influencing automatic (reflex-controlled) and attentional (high cortical) factors on dual task. Method : We used a dual-task model to examine attentional factors affecting 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 (COP) 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 early and late phases of the dual task trials that probably reflect 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 late phases when subjects were assigned nonverbal tasks. Less sway was observed during nonverbal task in a sequential study. Conclusion : 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.