This study investigated whether veterans with post-traumatic stress disorder (PTSD) would display a bias to interpret ambiguous faces in a more threatening way than veterans without the disorder. While there are a number of studies showing that high levels of anxiety are associated with a negative interpretive bias, there is only one published study investigating interpretive style in PTSD. Furthermore, all but one of these studies has relied on ambiguous words or sentences as the evocative stimuli. The current proposal extended extant studies by investigating how PTSD and control subjects responded to ambiguous emotional faces. Specifically, using morphing software, a set of faces were developed that were ambiguous with regard to their emotional expression. Participants were asked to categorize the emotional expression of both the newly created set of ambiguous facial images as well as the easily discernible, threatening and non-threatening faces that were used to create the ambiguous stimuli. All stimuli were presented optimally (2500 ms) to allow for full conscious awareness of the stimuli as well as suboptimally (30 ms followed by mask). The participants' behavioral categorizations of the faces as well as their facial physiological responses were the primary outcome variables. The results from the behavioral data suggest that there was weak evidence for a negative interpretive style in individuals with PTSD, but stronger evidence for a lack of a positive interpretive bias as compared to controls. In other words, PTSD subjects made significantly fewer non-threatening interpretations of ambiguous facial expressions than control subjects. Signal detection analysis suggested that controls, but not participants with PTSD, exhibited a positive response bias when evaluating ambiguous stimuli. Psychophysiological data revealed that participants with PTSD showed higher levels of baseline tension in the zygomaticus major facial muscle region, possibly due to paradigm response demands. Additionally, an exploratory analysis of the corrugator supercilii muscle region response to suboptimally presented faces suggested confirmatory support for the results from the behavioral data that PTSD participants are characterized by the absence of a positivity bias / acase@tulane.edu
| Identifer | oai:union.ndltd.org:TULANE/oai:http://digitallibrary.tulane.edu/:tulane_27471 |
| Date | January 2005 |
| Contributors | Jensen, Amy M (Author), Constans, Joseph I (Thesis advisor) |
| Publisher | Tulane University |
| Source Sets | Tulane University |
| Language | English |
| Detected Language | English |
| Rights | Access requires a license to the Dissertations and Theses (ProQuest) database., Copyright is in accordance with U.S. Copyright law |
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