Attention may influence the motor performance and frontal activity. This study will examine the effect of different attentional focus : internal, external and divided attention (dual task) on prefrontal cortical activation (fNIRS) and on gait performance. Thirty young healthy voluntary adults will participate in this study.

The subjects will be guided to walk at a normal pace while maintaining the required attentional focus. They will walk on 30 m five times in each of the four different focus conditions :1) no instructions about the attentional focus 2) internal focus on their feet movements, 3) external focus on two lines drawn on the floor, 4) divided attention (walking while performing an arithmetic task). A fNIRS system will be used for the prefrontal cortex activation evaluation and FeetMe soles for gait analyses.

Inclusion Criteria:

• Man or woman
• 18 -30 years old
• Informed consent obtained
• Free from any neurological, cardiologic, rheumatologic disorders.

Exclusion Criteria:

• Assisted walker.
• Disorders affecting gait.
• Concomitant medication likely to interfere with the results.