Seeing is believing: the role of 'preconscious' perceptual processing in delusional misidentification.

We have no introspective knowledge of the effects of preconscious processing on our perceptions. We are, therefore, not aware that our expectancies may have prejudiced our perceptions. Expectancies tend to foster perceptions with which they are consonant. Therefore false expectations, driven by false beliefs, may result in misperceptions which reinforce those false beliefs. This morbid cycle is central to the delusional misidentification syndromes. This cycle, with positive feedback, is intrinsically unstable, which helps to explain brief episodes of delusional misidentification. Good sensory data, strong links between sense data and memory, and good judgement will all help to prevent misperceptions. The less these constraints are disrupted, the stronger will be the psychological forces needed to generate a delusional misidentification. It is likely that suspiciousness generates particularly assertive effects on preconscious processing of perceptions. Abnormalities of perceptual processing in patients with schizophrenia explain their proclivity to delusional misidentification.