Implicit memory bias for threat in posttraumatic stress disorder

We employed a noise judgment task to investigate implicit memory bias for threat in Vietnam veterans with and without posttraumatic stress disorder (PTSD). Subjects first heard neutral (e.g, ''THE SHINYAPPLE SAT ON THE TABLE) and combat-relevant (e.g, ''THE CHOPPER LANDED IN HOT LZ'') sentences. Implicit memory for these sentences was tested by having subjects rare the volume of noise accompanying the presentation of these ''old'' sentences intermixed with ''new'' sentences, Implicit memory for old sentences is revealed when subjects rate the noise accompanying old sentences as less loud than the noise accompanying new sentences. Results revealed that under high noise volume PTSD patients demonstrated an implicit memory bias for combat-relevant sentences, whereas control subjects did not. This differential priming effect suggests that information about threat may be automatically accessed in PTSD.