Determine the effects looking in certain direction or moving the eyes in a certain way have on the ability of a subject to maintain equilibrium in different circumstances (eyes open/closed, and standing on hard or compliant surface, with the head straight or rotated right or left, flexed or extended).

Subjects will undergo computerized dynamic posturography (CDP) testing using the extended modified Clinical Testing of Sensory Integration in Balance (ext_mCTSIB) protocol: the subjects will be required to stand on a hard or the compliant surface in a comfortable posture, feet shoulder width, with eyes open or closed, arms to the side and free to move, gazing forward, and breathing normally, with head straight, turned right or left, flexed or extended. This testing will be used to determine the health status of the subjects.

Then a sequence of tests will be performed (they could be done in different days to avoid fatiguing the subject): each sequence will comprise of a baseline test in one of the ext_mCTSIB testing conditions and a subsequent test in the same conditions but with an oculomotor additional task, such as gazing in a specific direction other than straight, performing saccades in different directions, at different speed and using different paradigms (prosaccades, antisaccades, to a remembered target, gap saccades, …), following a target moving on the screen at different speed and in different directions, receiving an optokinetic stimulation in different directions and at different speeds. Video recordings of the eyes movement may be done to make sure that the subject is actually moving the eyes, to verify that the observers are well trained to detect and count the saccadic movements, as well as to obtain quantitative information regarding the eye movements per se.

Inclusion Criteria:

• Self assessed healthy subjects

Exclusion Criteria:

• subjects suffering from pathology known to affect balance