The Experience of Intrusions Scale: a preliminary examination.

Intrusive thoughts (i.e., unwelcome, distressing, involuntary thoughts) are prevalent in a variety of clinical conditions and are increasingly a focus of translational research. The goal of this study was to develop and preliminarily examine a brief self-report measure designed to assess clinically relevant aspects of the experience of intrusive thoughts related to a particular target. The Experience of Intrusions Scale (EIS) is a five-item measure that assesses the frequency, unpredictability, and unwantedness of intrusive thoughts, as well as the interference and distress caused by the intrusions, each on a five-point Likert-type scale. Five times over a four-] period, female undergraduates (N=160) completed the EIS in response to intrusive thoughts regarding a film clip depicting a sexual assault. On the first and last days, participants completed the EIS five minutes after watching the clip. In between film clip viewings, participants completed the EIS once per day. The EIS demonstrated good internal consistency, good to excellent test-retest reliability using both immediate post-stimulus and 24-hour time intervals, and convergent validity with two existing measures of intrusive phenomena: the White Bear Suppression Inventory (Wegner & Zanakos, 1994) and the Post-traumatic Stress Disorder Checklist-Civilian Version (Weathers, Litz, Herman, Huska, & Keane, 1993).