* The patient expresses an idea or belief with unusual persistence or force.
* That idea appears to exert an undue influence on his or her life, and the way of life is often altered to an inexplicable extent.
* Despite his/her profound conviction, there is often a quality of secretiveness or suspicion when the patient is questioned about it.
* The individual tends to be humorless and oversensitive, especially about the belief.
* There is a quality of centrality: no matter how unlikely it is that these strange things are happening to him, the patient accepts them relatively unquestioningly.
*An attempt to contradict the belief is likely to arouse an inappropriately strong emotional reaction, often with irritability and hostility.
* The belief is, at the least, unlikely.
* The patient is emotionally over-invested in the idea and it overwhelms other elements of his psyche.