Second, ORI is not associated with a singular event, but is repeated. Spitzberg and Cupach write, "Obsessiveness is reflected in the fact that the intruder is fixated on the target of attention; the intruder's thoughts and behaviors are persistent, preoccupying, and often morbid. Pursuit is persistent despite the absence of reciprocity by the obsessional object and despite resistance by the object." The episodes of unwanted behavior tend to escalate over time, with the seriousness rising and the time between incidents shortening.