Spatial Orientation, Navigation, and Neuropsychologic Function in Patients With Vestibular Implant

1. Patients receiving vestibular implants at UNIGE: Their inclusion criteria are defined as follows: * Deaf, scheduled for CI surgery * Minimum of five year history of documented absence of bilateral auditory and vestibular function, based on review of their audiograms and vestibular tests. * Vestibular testing consistent with BVL * No neurologic disease. note: these patients are recruited and implanted by the group at the University of Geneva Hospital (UNIGE) as part of their ongoing research. The study team are not involved in any way with the decision to surgically implant patients with cochlear or vestibular implants, nor are the researchers involved in any way with pre- or post-operative clinical care. The researchers only involvement is to perform the cognitive tests before, during, and after relatively short periods of stimulation using the vestibular implant (VI) 2. Vestibular patients tested at MEE: vestibular testing consistent with unilateral or bilateral vestibular damage. Both aspects of the study share the same exclusion criteria: Exclusion Criteria: * No known neurologic or otologic disease other than the vestibular and auditory deficits noted above. * Pregnancy. Pregnant women and women up to 4 months postpartum will be excluded because of the known effects and unknown potential effects of pregnancy on sensory function. * Body weight \>250 lbs (due to motion device safety limits) * The chronic use of vestibular suppressant medication (benzodiazepine, antihistamine, anticholinergic) * Inability to stand or walk unassisted. * Blindness. * Unstable medical condition. * Orthopedic or musculoskeletal injuries/conditions that affect gait or balance. * Ongoing neck or spinal pain/injuries or recent history of neck or spinal surgery * Amputation, musculoskeletal deformity, or significant leg-length discrepancy * A history of severe head trauma. * Any major psychiatric disorder (e.g., psychosis, schizophrenia, panic disorder), not including anxiety or depression. * Severe heart or pulmonary conditions * Active cancer for which chemo-/radiation therapy is being received.