Inclusion Criteria:  Age: 18-85 Fluent in English Normal or corrected-to-normal vision Able to participate in study activities Passed Johns Hopkins Medicine Outpatient Office COVID-19 screening checklist within 24 hours of study visit.  Exclusion Criteria:  Hospitalization for heart failure, stroke or major cardiac event (myocardial infarction) within past 3 months. History of chest pain during exercise (angina). High blood pressure needing more than 1 medication for treatment. Blood pressure at rest exceeding systolic blood pressure (SBP) 150 millimeters of Mercury (mmHg), diastolic blood pressure (DBP) 100 mmHg. Heart rate at rest exceeding 100 beats per minute (bpm). Abnormal ECG, indwelling pacemaker or cardiac defibrillator. Home oxygen prescription. Women who or are pregnant or suspect they may be pregnant.