Hallucinations Are Far More Common Than Most People Think

Have you ever heard voices in your head without anyone actually talking to you? Or did you ever see things that were, in fact, not really there?

Psychologists call such an experience, which occurs without an external stimulus, a hallucination. Experiencing a hallucination can be quite distressing for people, as hallucinations are most widely associated with psychotic disorders like schizophrenia—and in fact, hallucinations are indeed common in several subtypes of schizophrenia. Therefore, somebody experiencing a hallucination may wonder “Am I losing my mind?“ or “Am I going crazy?”

What is not well known, unfortunately, is how common hallucinations are in non-clinical groups without a psychotic disorder diagnosis. Such knowledge would be important in order to have a realistic view of whether it is actually a reason for concern if somebody experiences a hallucination or whether it may also be a harmless occurrence.

A new study, recently published in the scientific journal Psychology and Psychotherapy, had the aim of closing the gap in the literature on how common hallucinations are in non-clinical groups (Aynsworth et al., 2022). Let's have a look at the findings of this study.

What Did the Scientists Do?

In the study, data from 466 volunteers with a mean age of about 21 years were collected by the scientists. Each volunteer filled out a questionnaire called MUSEQ (short for "Multimodal Unusual Sensory Experiences Questionnaire"). The MUSEQ contained questions like “I Have seen lights, flashes, or other shapes that other people could not see.”

For each question, volunteers had to indicate whether they had that experience "never," "hardly ever," "rarely," "occasionally," or "frequently." Next, the scientists asked the volunteers a few follow-up questions to determine whether an experience would adhere to a clinical definition of visual hallucinations—for example, whether they experienced the hallucinations while fully conscious or not.

What Did the Scientists Find Out?

The results of the study strongly suggest that visual hallucinations are surprisingly common in healthy people.

Overall, 84.8 percent of the volunteers that took part in the study reported having experienced some form of anomalous visual experiences in their life. More than a third of them (37.8 percent) reported that they had experienced an actual visual hallucination similar to what a patient with a psychotic disorder may experience. When the scientists analyzed the additional questions of whether an experience would agree with a clinical definition of visual hallucinations, about 17.4 percent of volunteers had experienced a hallucination that met these criteria.

When asked further about their experiences, most volunteers in the study reported that the hallucinations primarily happened when they were alone and in the evening. When asked to speculate on possible reasons for the hallucinations, most volunteers indicated that they were either tired or their minds were "playing tricks on them." However, some volunteers also reported that they felt the hallucination may be a threat to their mental health and were quite distressed by it.

Hallucinations Are Common

Taken together, the results of the study suggest that about 17 to 38 percent of healthy people experience visual hallucinations. This clearly shows that experiencing a single visual hallucination is likely a common experience and not necessarily a reason to worry that one is suffering from psychosis. In fact, the authors of the study argue that it is important to normalize the experience of visual hallucinations—so that when people do experience one, they're less likely to react negatively.

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