Veterans with Posttraumatic Stress Disorder (PTSD) will be randomly assigned to either Attention Bias Modification Treatment (ABMT) designed to reduce bias toward threat or a placebo control condition not designed to change attention patterns. Outcome measures will be PTSD, anxiety, depression, and alexithymia symptoms as measured by standard psychological interviews and questionnaires. Participants will also be invited to participate in physiological testing before and after receiving AMBT or placebo to serve as additional outcome measures and assess brain functioning, heart rate, and muscle tension.

The investigators expect to see significant PTSD symptom reduction in the Attention Bias Modification Treatment (ABMT) group relative to the placebo control group in which no symptomatic relief is expected. At the end of the study, if ABMT is shown to be effective, we will offer active ABMT to those participants randomly assigned to the placebo arm if they would like to receive the treatment.

Inclusion Criteria:

• Veterans with Posttraumatic Stress Disorder (PTSD) serving in United States Military after March 20, 2003.

Exclusion Criteria:

• Schizophrenia
• Bipolar Disorder
• Obsessive Compulsive Disorder
• Head Injury with Loss of Consciousness for more than 30 minutes
• Active Alcohol/Substance Dependence in past 6 months