The prisoner's cinema (also known as the prisoner's cinema phenomenon) is a term used to describe the entoptic (within-eye) occurrence experienced by an individual that has been deprived of light or visual stimuli for extended periods of time.
It is usually a result of isolation via imprisonment, meditative trance states, or other forms of sensory deprivation and appears to the individual as spontaneous hallucinations or "light show" style imagery that emerges out of the darkness with either open or closed eyes. Astronauts and other individuals who have been exposed to certain types of radiation have reported witnessing similar phenomena.
It has been suggested that the hallucinations are a result of high levels of phosphene production. There is also anecdotal evidence suggesting that the shapes of these hallucinations may take on that of geometrical form constants. Additionally, it has been speculated that the hallucinations can take on other, more abstract, or nebulous forms including (but not limited to) shapes, faces, figures, places, or even an entire production of full-on imaginary scenarios.
This effect is not to be confused with internal hallucinations, Charles Bonnet syndrome (i.e. the experience of complex visual hallucinations in one with partial or severe blindness), hypnagogia, or the hallucinations that can be induced by meditation.
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