The order of attentional focus instructions affects how postural control processes compensate for multisensory mismatch: a crossover study.

Directing attention during balance training can have an immediate and lasting impact on a patient's balance and ultimately decrease the risk of future falls. However, it is unclear how attention can best be utilized to improve postural control. The current study uses a 2 × 2 crossover design to investigate the potential impact of receiving multiple verbal instructions during a single session of sensorimotor control testing for balance. Twenty-eight healthy adults were tasked to balance on a rocker board while immersed in virtual reality (VR). The VR created a multisensory mismatch between visual VR motion and body motion. The strength of the relationship between visual motion and body motion was measured to assess visual dependence. Alpha and theta frequency bands in electroencephalography (EEG) recordings were also analyzed to identify potential neural correlates of visual dependence and postural stability. Participants were randomized into two groups: one group was first instructed to keep the board leveled (external focus) and then instructed to keep both feet leveled (internal focus) to help maintain stability. The other group was given these two instructions in reverse order. Analyses focused on time, instruction, and group effects from receiving multiple instructions. Results revealed that when participants are given external focus first, and internal focus second, they are more likely to demonstrate lower visual dependence and better postural stability throughout the entire session than participants given internal focus first and external focus second. However, channel-level EEG analyses did not reveal differences between the groups. Current findings suggest that the order of attentional focus instructions may influence how the postural control system resolves sensory incongruence during a single testing session.