Does post-event cognitive load undermine thought suppression and increase intrusive memories after exposure to an analogue stressor?

Ironic process theory has been used in part to explain the phenomenon of intrusive memories in various disorders including post-traumatic stress disorder. How thought suppression interacts with other cognitive processes believed to be instrumental in the development of traumatic intrusive memory was tested. In an analogue design 120 participants were randomised to five conditions, four of which also required participants to attempt to suppress intrusive memories after viewing a film of traumatic content. Participants in three conditions were also required to perform concurrent tasks that acted as a cognitive load during suppression. Intrusive memories were recorded during the experimental phase and at 1-week follow-up. Contrary to predictions, post-film processing did not undermine suppression success. There was some suggestion that post-film processing resulted in those participants experiencing intrusions of shorter duration than the no-suppression control group in two 5-minute intrusion monitoring intervals at the initial and follow-up phase of the experiment, but this was not reflected in a 1-week diary measure of intrusions. All experimental groups performed in a similar fashion in terms of memory testing of the film's content. The findings are discussed in the context of ironic process theory and cognitive models of post-traumatic stress.