An obsession is an "undesired, unpleasant, intrusive thought that cannot be suppressed through the patient's volition", but unlike passivity experiences described above, they are not experienced as imposed from outside the patient's mind. Obsessions are typically intrusive thoughts of violence, injury, dirt or sex, or obsessive ruminations on intellectual themes. A person can also describe obsessional doubt, with intrusive worries about whether they have made the wrong decision, or forgotten to do something, for example turn off the gas or lock the house. In obsessive-compulsive disorder, the individual experiences obsessions with or without compulsions (a sense of having to carry out certain ritualized and senseless actions against their wishes).