Tehran University of Medical Sciences Iranian Journal of Psychiatry 1735-4587 8 3 2013 09 15 124 30 Abass Abolghasemi Department of Psychology, University of Mohaghegh Ardabili University of Mohaghegh Ardebili, Ardabil, Iran Fereshteh Bakhshian Department of Psychology, University of Mohaghegh Ardabili University of Mohaghegh Ardebili, Ardabil, Iran Mohammad Narimani Department of Psychology, University of Mohaghegh Ardabili University of Mohaghegh Ardebili, Ardabil, Iran 2015 10 14 Objective: The purpose of the present study was to compare response inhibition and cognitive appraisal in clients with acute stress disorder, clients with posttraumatic stress disorder, and normal individuals . Method:  This  was a comparative study. The sample consisted of 40 clients with acute stress disorder, 40 patients with posttraumatic stress disorder, and 40 normal individuals from Mazandaran province selected through  convenience  sampling  method.  Data  were  collected  using Composite International Diagnostic Interview, Stroop Color-Word Test, Posttraumatic Cognitions Inventory, and the Impact of Event Scale. Results:  Results showed that individuals with acute stress disorder are less  able  to  inhibit  inappropriate  responses  and  have  more  impaired cognitive   appraisals   compared   to   those   with   posttraumatic   stress disorder. Moreover, results showed that response inhibition and cognitive appraisal explain 75% of the variance in posttraumatic stress disorder symptoms  and  38%  o   the  variance  in  posttraumatic  stress  disorder symptoms . Conclusion: The findings suggest that response inhibition and cognitive appraisal are two variables that influence the severity of posttraumatic stress disorder and acute stress disorder symptoms. Also, these results have important implications for pathology, prevention, and treatment of posttraumatic stress disorder and acute stress disorder. https://ijps.tums.ac.ir/index.php/ijps/article/view/127 https://ijps.tums.ac.ir/index.php/ijps/article/download/127/123