When people experience delusions or hallucinations there is usually some loss of contact with reality whereby normal processes of thought and perception are disturbed. As humans, we are all susceptible to experiencing anomalous mental states such as this. In everyday life, for example, mentally healthy people distort reality to enhance their self-esteem and maintain beliefs about their self-agency.
When faced with negative, ambiguous or unsupportive feedback, we often respond with exaggerated perceptions of control and unrealistic optimism. In some life situations – in states of delirium, bereavement, severe lack of sleep and sensory deprivation – it is not uncommon for hallucinations to occur. The idea that delusions and hallucinations are a sign of illness or pathology tends to emerge when the belief or experience occurs outside of such situations and is held to be true in the face of strong contradictory evidence.
In a delusion where a person believes that electronic listening devices are implanted in their brain, for example, the implausibility of the belief is obvious to everyone else around, but is held with an unshakeable conviction by that person. Similarly, when hallucinations occur, such as the hearing of non-existent voices, the person experiencing the hallucinatory speech may nonetheless believe that others can hear the voices too (and are lying when they say they cannot), or even attribute the experience to the possession of a special power such as telepathy.
The Three Christs of Ypsilanti
Problems in the self-recognition of such mind states seem to occur even when they lead to personal distress and severe disruptions to quality of life. But this difficulty in self-recognition does not necessarily come from a lack of rational thought. In a 1960s study, The Three Christs of Ypsilanti, psychologist Milton Rokeach observed what would happen when three people, each firmly believing they were Jesus, lived together in very close proximity for several months.