Cognitive demand and sensory modality influence the impact of a cognitive task on postural control


To address the current variability in the posture-cognition data, the aim of the present experiment was to evaluate the modulating effects of cognitive demand and sensory modality on postural control in young adults. Seventeen healthy young adults (23.71 ± 1.99 years; 9 F, 8 M) were instructed to stand feet together on a force platform while concurrently performing cognitive tasks of varying difficulty (easy, moderate, and difficult) and sensory modality (auditory and visual). The auditory tasks consisted of silently counting the total occurrence of one or two letters in a sequence of individual letters or three-letter words and completing a string of words broken down into individual letters. The visual tasks consisted of silently counting the total occurrence of one or two numbers in a 3-digit and 5-digit number sequence. Increasing cognitive demand resulted in a significant reduction in area of 95% confidence ellipse and medial-lateral (ML) sway variability. Presenting the cognitive tasks visually resulted in a greater reduction in ML sway variability compared to auditorily presenting the tasks. Contrary to previous literature (Pellecchia, 2003; Prado et al., 2007), the present findings suggest that visually presented cognitive task of higher demand can facilitate greater postural stability. The observed improvement may be a result of a shift in attention and the establishment of a visual anchor.