Perceptual Implicit Memory for Trauma-related Information in Post-traumatic Stress Disorder

We used a perceptual identification paradigm to investigate whether Vietnam combat veterans with post-traumatic stress disorder (PTSD), compared to healthy combat veterans, exhibit an implicit memory bias for trauma-related information. Subjects viewed a series of trauma, positive, and neutral words, and subsequently saw these "old" words intermixed with an equivalent number of "new" distractor words of the same types. During this test phase, each word appeared for 100 milliseconds and was replaced by a visual mask. Although both groups exhibited implicit memory by accurately identifying more old words than new words, this priming effect was not enhanced for trauma words in the PTSD group. Tasks that primarily tap perceptual implicit memory may be relatively insensitive to emotional variables.