• Male and female subjects 18-66 years of age

• Healthy volunteers or volunteers with a diagnosis of ADHD in adulthood, meeting the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) \[American Psychiatric Association, 2013\] criteria, including at least 5 moderate inattentive or impulsive-hyperactive symptoms, and onset of two symptoms of inattentive or of impulsive/hyperactive traits by the age of 12.

• Patient will be either off stimulant medications or, if undergoing treatment with stimulants, will be asked to discontinue two days prior to the experiment, under physician-guided protocol, and allowed to resume afterwards. Subjects may resume stimulant use between the two study visits so long as they discontinue use two days prior to the second study visit. If fatigue is problematic in subjects discontinuing medication, they will be allowed to continue with the study if they are able to follow the suggested taper plan (50% of the dose day one, 25% dose day 2, stop day of visit (day 3)).

• English-speaking