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.