Effects of a reaction time task on postural control in humans

The purpose of the present experiments was to investigate the effects of a reaction time (RT) task on postural control, du ring and following the exec ution. Th ree different RT tasks consisting in verbal responses to visual a nd auditory stimuli were supposed to require different demands on cognitive resources. There was also a control condition in which no concurrent task was required. Postural control was assessed using a force platform. Results showed that (1) center of foot pressure (COP) displacements significantly decreased while concurrently performing the RT tasks, (2) this effect laste d for at least 10 s following the secondary task performance and (3) COP di splacements decreased similarly, whatever the attentional requirements of t he secondary task. (C) 2000 Elsevier Science Ireland Ltd. All rights reserv ed.