While individual hallucinations are relatively common, group hallucinations are extremely rare. Hallucinations are subjective perceptions that occur in the absence of corresponding external stimuli. They are typically experienced only by the individual and are not directly observable or shareable by others.
However, there are some reported instances of group-like perceptual experiences that may be mistaken for group hallucinations. These are often known as "collective illusions" or "mass hysteria." In such cases, a group of people may report similar or related perceptual experiences, but these experiences are not true hallucinations in the sense of perceiving something that is not there.
Collective illusions or mass hysteria are usually influenced by social and psychological factors. They can occur in situations where a group of people is exposed to a powerful suggestion, fear, or emotional arousal, leading them to perceive something in a similar way. Examples of collective illusions include:
UFO sightings: In some cases, multiple people may claim to have seen a UFO or unidentified flying object, but these reports are often influenced by media coverage or stories circulating in the community.
Religious visions: There have been instances of groups of people reporting visions of religious figures or supernatural phenomena during religious gatherings or events. These experiences are often shaped by religious beliefs and expectations.
Shared delusions: Although not hallucinations, some groups of people may develop shared delusional beliefs, known as "folie à deux" or "shared psychosis." In these cases, one person with a delusional belief can influence and convince others within close relationships or social circles to adopt the same belief.
It's essential to differentiate between genuine group hallucinations and these collective perceptual experiences. True group hallucinations, where multiple individuals simultaneously experience the exact same hallucination without any external stimulus, are not scientifically supported or well-documented. On the other hand, collective illusions and shared perceptual experiences are intriguing phenomena that highlight the social and psychological aspects of human perception and cognition.