The purpose of this study is to test the effects of a computerized approach/avoidance training (AAT) procedure on behavioral, affective, and brain mechanisms that are important for reward sensitivity and well-being in individuals diagnosed with major depression. The training procedure is designed to modify automatic approach responses for positive social stimuli. The primary aim is to determine the effects of approach/avoidance training on the functioning of brain systems during reward processing in individuals diagnosed with major depression. A secondary aim will determine whether brain activation patterns following approach/avoidance training predict subsequent affective and behavioral responses during reward processing. An exploratory aim will test whether completing the approach/avoidance training procedure in combination with a brief computer-delivered behavioral activation program for depression will produce larger changes in depression symptoms, positive emotions, and social relationship functioning from pre- to post-intervention compared to the control training procedure.

Inclusion Criteria:

• Ages 18-55
• Principal psychiatric diagnosis of major depressive disorder
• Patient Health Questionnaire - 9 item score ≥ 10
• Ability to read and speak English sufficiently to complete study procedures

Exclusion Criteria:

• History of psychosis, mania, or substance dependence
• Current severe medical disorder that requires inpatient treatment or frequent medical follow ups including but not limited to: unstable hypertension, unstable angina, unstable diabetes mellitus, unstable cardiac arrhythmias, transient ischemic attacks, sever coronary artery disease, sever peripheral vascular disease, severe hepato-gastro-intestinal disease, severe infectious disease (e.g. HIV), recurrent severe headache or migraine, fainting spells, seizures, and history of traumatic brain injury with loss of consciousness > 30 minutes
• Current use of the following medications: antidepressants, benxodiazepines, antipsychotics, mood stabilizers, or other drugs that can acutely affect the hemodynamic response (methylphenidate and acetazolamide)
• Caffeine intake > 10 cups/day or recent significant changes in consumption
• MRI exclusions, including claustrophobia, cardiac pacemaker, metal fragments in eyes/skin/body (shrapnel), aortic/aneurysm clips, prosthesis, by-pass surgery/coronary artery clips, hearing aid, heart valve replacement, shunt (ventricular or spinal), electrodes, metal plates/pins/screws/wires, or neuro/bio-stimulators (TENS unit), persons who have ever been a metal worker/welder, history of eye surgery/eyes washed out because of metal, women who are or may be pregnant (determined by a positive pregnancy test), women using an intrauterine device, vision problems uncorrectable with lenses, inability to lie still on one's back for 60 minutes; prior neurosurgery; older tattoos with metal dyes; unwillingness to remove nose, ear, tongue or face rings.
• Concurrent psychosocial treatment: Participants completing ongoing psychosocial treatment will be required to meet a 12-week stability criteria so that symptom changes as a result of other psychosocial treatments are not confounded with changes due to the research.
• Inability to complete the initial assessment battery or behavioral training sessions.
• Clinical conditions assessed by the interviewer that necessitate more imminent clinical care (e.g., active suicidal ideation). These criteria are in place so participants with these other, more several symptoms can be referred for appropriate mental health services.