Psychological processes and paranoia: implications for forensic behavioural science

Paranoid delusions have recently become the focus of empirical research. In this article, we review studies of the psychological mechanisms that might be involved in paranoid thinking and discuss their implications for forensic behaviour science. Paranoia has not been consistently associated with any specific neuropsychological abnormality. However, evidence supports three broad types of mechanism that might be involved in delusional thinking in general and paranoia in particular: anomalous perceptual experiences, abnormal reasoning, and motivational factors. There is some evidence that paranoia may be associated with hearing loss, and good evidence that paranoid patients attend excessively to threatening information. Although general reasoning ability seems to be unaffected, there is strong evidence that a jumping- to-conclusions style of reasoning about data is implicated in delusions in general, but less consistent evidence specifically linking paranoia to impaired theory of mind. Finally, there appears to be a strong association between paranoia and negative self-esteem, and some evidence that attempts to protect self-esteem by attributing negative events to external causes are implicated. Some of these processes have recently been implicated in violent behaviour, and they therefore have the potential to explain the apparent association between paranoid delusions and offending.