{ "participant_id": { "Description": "Unique participant identifier" }, "age": { "Description": "Age of the participant at time of testing", "Units": "years" }, "sex": { "Description": "Biological sex of the participant", "Levels": { "F": "female", "M": "male" } }, "hand": { "Description": "Handedness of the participant", "Levels": { "R": "right", "L": "left", "A": "ambidextrous" } } }