If investigators know that the anticipatory mechanisms involved in precision grip take into account the gravity, however it is unclear how they adapt to changes in the gravitational level. The objectives of this study are to study and model the movement control and the mechanisms underlying learning and adapting to the condition of weightlessness. Specifically, i) investigators will determine if a change in the level of gravity is taken into account when controlling grip force and ii) investigators will examine the effects of gravity change on hand-eye coordination.

Inclusion Criteria:

• Healthy volunteers, male or female
• 18 to 65 years
• Affiliated with a Social Security plan or holder of a European Health Insurance Card (EHIC - European Health Insurance Card - EHIC).
• Having an aeronautical medical certificate of fitness for flight personnel unprofessional functions in civil aviation.
• Agreeing to participate in the study
• Having given informed consent

Exclusion Criteria:

• person not affiliated to a Social Security Inssurance,
• person who participated in a clinical trial within the trial below the exclusion period,
• person with a medical history or any acute or chronic condition that can affect the test results, or by running a risk on during the protocol, especially topics: past or present history of neurological disease, rheumatologic or otologic (hearing or equilibration) OR person with a corrected visual acuity of less than 5 / 10th.
• pregnant women.