Effect of articulatory and mental tasks on postural control

THE present study sought to determine whether the increased postural instab ility produced by a spoken mental task was due to competing demands for att entional resources or perturbation of posture by articulation. Postural swa y was measured in 36 normal subjects under the following conditions: repeat ing a number aloud (articulation), counting backwards aloud in multiples of seven (articulation and attention), counting backwards silently (attention ), and no mental task (neither articulation nor attention). Articulation re sulted in a significant increase in sway, whereas no effect of attention wa s observed. We conclude that in order to accurately assess the effect of at tentional demands on postural control, it is important to eliminate or cont rol the effects of articulation. (C) 1999 Lippincott Williams & Wilkins.