Case-control study;
The effect of counterfactual thinking on retrospective control perceptions in posttraumatic stress disorder.

Counterfactual thinking (CFT) can be described as considering alternative outcomes of past events and has been found to be positively associated with syptoms of posttraumatic stress disorder (PTSD). The present study assesses whether the generation of CFT leads to enhanced retrospective control perceptions over the traumatic event in a sample of trauma-exposed individuals. Differential effects are compared among a group of individuals that are diagnosed for PTSD and a healthy control group. Is is expected that the PTSD group will generate more characterological counterfactuals which will not be associated with increaes in control perception. The healthy control group is expected to generate more behavioral counterfactuals which in turn will lead to increased control perceptions.

1. The generation of behavioral and controllable CFTs will lead to increased retrospective control perceptions in both groups,;

2. The PTSD group will generate more characterological and uncontrollable counterfactuals relative to the comparison group.

Participants will write down their traumatic event. They will then rate the event on their perceived control over the outcome of the event. After that, they will be instructed to engage in counterfactual thinking concerning the traumatic event by generating thoughts that begin with "What if -?". After performing this task, participants will rate their perceived control over the event again. Thereby, a pre-post counterfactual difference score will be obtained and used as the dependent variable.