Inclusion Criteria:  between ages of 18 and 50 ability to sufficiently speak and understand English so as to be able to understand and complete cognitive tasks ability to give valid informed consent  Exclusion Criteria:  no history of head trauma no current or previous history of treatment with psychotropic medication corrected vision 20/30 or better tDCS/MRI contraindications, including: pregnancy, ferrous metal in any part of the body, serious medical conditions, claustrophobia, metallic implants, skin damage, conditions such as eczema at electrode sites, cranial pathologies