Motion effects on intrusion development.

Analogue studies on intrusion development have found that visuospatial tasks performed during the encoding of aversive information reduce subsequent intrusion development. However, these studies cannot rule out a physical explanation in terms of simple movement. In the current study we addressed this issue. Healthy participants viewed an aversive film while performing a visuospatial movement task, a configurational movement task, or no task. Intrusive images from the film were reported in a diary during the week following film viewing. In line with an information-processing account of posttraumatic stress disorder, intrusion frequency was significantly reduced by the visuospatial movement task but not the configurational movement task compared to no task. This finding supports the role of visuospatial processing specifically in intrusion development.