Inclusion Criteria:  Age 18-80 and able to provide informed consent. Have a diagnosis of Parkinson's disease, essential tremor, or cervical dystonia made by a movement disorders specialist. Medically optimized without planned medication changes for the duration of the study. For patients with ET, they will have a score of at least 2 on items 5 and 6 of the Fahn-Tolosa-Marin (FTM) Tremor Rating Scale. For patients with dystonia, they will have abnormal dystonic postures of the head and not isolated head tremor  Exclusion Criteria:  The presence of additional neurologic diseases, that might confound testing or the coexistence of PD and ET together (action tremor that was present prior to the development of parkinsonism). Symptoms of peripheral neuropathy at the wrist (reduced vibratory, pinprick, or temperature sensation) Montreal cognitive assessment (MoCA) score < 20 or previously documented dementia Unable to walk without a walking aid (e.g. cane, stick, walker)