Could paranoia be a visual issue?

People with paranoia mistakenly believe that others wish to harm them. These misperceptions are generally assumed to stem from errors in how that person thinks about the world, including other people. However, some researchers have proposed that basic sensory errors might underpin what seem to be errors in thinking. There is research finding that people with schizophrenia often have problems with integrating information from different senses, for example, and it's been suggested that this might lead their brains to jump to incorrect conclusions about what it is that they're actually experiencing.

A recent study led by Santiago Castiello and colleagues, published in Communications Psychology, has produced findings that support the idea that basic errors in perceptions might lead to mistakes in thinking. Their research showed that people with heightened paranoia, and also people who scored highly for 'teleological thinking' — which means that they over-ascribe meaning or purpose to events that have neither — were more prone to what the team call visual 'social hallucinations'.

The research involved four online experiments on a total of more than 600 adults. In the first, participants watched clips in which differently coloured discs moved around a screen. In some of these videos, one dot (named the 'wolf') was 'chasing' another (the 'sheep'), by following its trajectory, at least to some extent. In other clips, this did not happen. On each trial, the participants had to decide whether a chase was happening. In the second study, the team added confidence ratings, which enabled this fresh batch of participants to indicate how sure they were that a chase was happening. The team also gathered questionnaire data on their levels of paranoia or teleological thinking.

The results of these studies showed that people with either heightened paranoia or heightened teleological thinking more often — and more confidently — felt that one dot was chasing another, when it wasn't. In other words, they perceived that a social interaction was taking place, though it was not.

In subsequent studies that also featured the moving discs, participants were asked to identify which dot was the 'wolf' and which was the 'sheep'. The team found that people with heightened paranoia were worse at identifying the 'sheep' but not the 'wolves' — in other words, when a chase was happening, they struggled to identify who, exactly, was being chased — whereas people with heightened teleological thinking were worse at identifying the 'wolves', but not the 'sheep'. "This pattern suggests that… different kinds of aberrant thought about intentions may be associated with strikingly specific forms of social perception," the researchers write.

Overall, their results suggest that people with heightened paranoia or teleological thinking are more likely to hallucinate visual social interactions. The results of other questionnaires that the participants completed also indicated that these people were more likely to have hallucination-type experiences in their everyday lives.

"On these bases, we suggest that aberrant beliefs about intentions may relate to social hallucinations in vision," the team writes.

These findings sit well beside the observation that people who are blind from birth are far less likely to develop schizophrenia or another type of psychosis than people with normal vision. One possible explanation is that someone who can't see cannot experience errors in visual processing that might otherwise cause them to make mistakes in their thinking. Castiello shared his sentiments in a press release statement, "Finding these social hallucinations in vision makes me wonder if schizophrenia is something that develops through errors in how people sample the visual world."

However, there is still a lot of debate about whether faults in visual processing led to 'bottom-up' errors in inferences and so thinking, or whether erroneous thinking (paranoia and teleological thinking, for example) causes 'top-down' changes in how the visual system processes the world. This new study can't answer this question. However, there is a third possibility, the team writes: that 'social hallucinations' are "located somewhere between" vision and inferences.

Further work will be needed to explore all these possibilities. But these results do suggest that links between how we see the world and how we think about the world might be closer than we often assume.

On a more immediately practical note, the researchers also suggest that it might be possible to use a version of the moving disc task to predict a person's risk of developing psychosis — and so identify people who might need clinical support.

Read the paper in full:
Castiello, S., Ongchoco, J.D.K., van Buren, B. et al. (2024). Paranoid and teleological thinking give rise to distinct social hallucinations in vision. Communications Psychology. 2, 117. https://doi.org/10.1038/s44271-024-00163-9

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