1. Psychiatric disease: Psychiatric criteria (DSM-IV) will be used to determine exclusion of volunteers with psychiatric illnesses. A psychological interview by a trained clinician to determine diagnoses. We will exclude participants with any disorders or psychiatric diagnoses, including, but not limited to; schizophrenia, bipolar disorder, current/active and untreated depression or generalized anxiety, post traumatic stress disorder, attention deficit hyperactive disorder, past history of eating disorders without successful treatment within 3 yrs, will not be allowed.