<prompt> Perceptual misinterpretation of a real object isIllusionDelusionHallucinationSchizophrenia  <response>: Ans. is a i.e. Illusion Both illusion and hallucination are perceptual disorders.In illusion there is misinterpretation of the actual stimulus whereas in hallucination perception occurs in the absence of any stimulus.Illusion -Misinterpretation of rope as snake.Hallucination - Able to see snake without any ropeDelusionIt is the disturbance in the content of thought.It is a belief based on incorrect inference about external reality and not consistent with patients intelligence and sociocultural background.DeliriumIt is used as a general term for the quite cognitive impairment syndrome.Delirium is characterized by global impairment in consciousness, resulting in reduced level of alertness, attention, and perception of the environment. 