Post-traumatic stress disorder (PTSD) is characterized by hypervigilance. In particular, previous works suggest that patients tend to scan constantly the environment for possible threats. The present project aims at investigating such attentional bias in patients with PTSD using the change blindness paradigm that offers the interesting possibility of studying sensitivity to sudden changes using ecological stimuli. More precisely, the investigators will investigate whether patients are more sensitive than matched controls to sudden changes in the visual environment and whether this hypersensitivity is specific or even stronger when visual information has an emotional content. The attentional bias will be measured using motor responses (accuracy and speed to indicate the occurrence of a change by pressing a button) as well as eye movements.

Inclusion Criteria:

• a diagnosis of PTSD based on the standard DSM-IV criteria,
• normal or corrected vision.
• clinically stable at the testing time

Exclusion Criteria:

• history of neurological illness or trauma that occurred in the previous six months, - pregnant and nursing women,
• drugs use in the last 24 hours,
• an acute ocular disorder.
• Participants will not be under tutorship, curatorship or deprived of liberty.

Thirty patients with PTSD and 30 participants exposed to trauma without PTSD will be asked to detect neutral or emotional changes in 96 scenes.