Where paranoid delusions come from

Differences in social status and politics encourage paranoid thinking

University College London

Differences in social status and political belief increase paranoid interpretations of other people's actions, finds a new UCL experimental study.

Paranoia is the tendency to assume other people are trying to harm you when their actual motivations are unclear, and this tendency is increased when interacting with someone of a higher social status or opposing political beliefs, according to the study published in Royal Society Open Science.

"Being alert to social danger is key to our survival, but our results suggest social difference alone encourages us to think that the other person wants to harm us," said the study's senior author, Professor Nichola Raihani (UCL Psychology & Language Sciences).

"Intense paranoia is also a symptom of mental ill health, and is more common among people who perceive themselves to have low social rank. We believe our findings could shed light on why paranoia is more common in those who are struggling on the social ladder and excluded by society," she added.

For the study, 2,030 people participated in an online experiment where they were paired with another person and given a sum of money. 

Ahead of the experiment, all participants had reported their typical levels of paranoid thinking by filling out a questionnaire, as well as their own perceived social status and their political affiliation along the liberal-conservative spectrum. They were then paired with someone from a higher, lower or similar social status, or with someone who had similar or opposing political beliefs.

In each pair, one person got to decide whether to split the money 50-50 or to keep it all for themselves. 

The other person was then asked to rate how much they thought the decision was motivated by the decider's self-interest, and how much the decision was likely motivated by the decider wanting to deny them any of the prize -- a measure of perceived harmful intent. The roles were then swapped with a new sum of money.

People who were paired with someone with a higher social status or with different political beliefs more frequently assumed their partner's decision had been motivated by wanting to cause them harm. In contrast, social difference did not affect how often people assumed their partner was motivated by self-interest.

Researchers also found that the over-perception of other people's harmful intentions occurred at the same rate, regardless of whether participants already had heightened levels of paranoid thinking.

"Our findings suggest that people who struggle with high levels of paranoia are equally well-tuned to social difference despite sometimes seeming that they misperceive the social world. This research may help us understand how exclusion and disadvantage fuel some of the most severe mental health problems," said co-author Dr Vaughan Bell (UCL Psychiatry).

The researchers were funded by the Royal Society and Wellcome.