<prompt> A person identifies a pattern on wall as an animal is having:HallucinationDelusionIllusionSensory distortion  <response>: Ans: c IllusionIllusion:Misinterpretation of stimuli arising from an external object. There are three types:i Complete illusion: depends on inattention of the person. For eg: misreading words in newspapers missing misprints, we read the word automatically as if it were complete. It also depends on our previous experience interests. For eg: to the person with an interest in reading, _ook may be misread as book even though the faded letter is 1.ii Affect illusions: Arising in the context of a particular mood state, eg: young child wakes up scared in the middle of the night and misinterprets a white towel as a ghost.iii Pareidolia: Vivid illusions of excessive fantasy thinking. For eg: the subjects sees vivid pictures in fire cloudspattems on walls.Hallucinations:Perceptions without an adequate external stimulus.Special types of hallucinations;i Functional hallucinations: Hallucinations which require the presence of another real sensation. For eg: patient hears the voice of God hallucination as her clock ticked real sensation.ii Reflex hallucianations: Morbid form of synaesthesia.Synaesthesia: experience of a stimulus in one modality produces a sensory experience in another.For eg: patients can feel, taste and hear Flowers simultaneously in reflex hallucination: stimulus in one sensory field produces a hallucination in another. For eg: patient feels pain in her head somatic hallucination when she heard someone sneeze the stimulus.iii Extracampine hallucinations: it has hallucinations outside the limits of the sensory field. For eg: patient hears the voices of the people in Delhi when he is in Kerala.iv Hypnagogic hallucinations: hallucinations which occur when subjects go to sleep.v Hypnapompic hallucinations: hallucinations which occurs when subject wakes up from sleep.CHARLES- BONNET SYNDROME:Complex visual hallucinations occur in the absence of any psychopathology and in clear consciousness.Associated with central peripheral reduction in vision.BODY IMAGE DISTORTIONS:i Hyperschemazia: perceived magnification of body parts.ii Aschemazia: perception of body parts as absent.iii Hyposchemazia: perception of body parts as diminished.iv Paraschemazia: feeling that body parts are distorted twistedseparated from the rest of the body.v Hemisomatognosia: unilateral lack of body image- person behaves as if one side of body is missing.vi Anosognosia: ddenial of illness.vii Somatoparaphrenia: patients showing bizarre attitude to their paralysed limb. They feel they have too many distorted inanimate limbs.KORO: belief that the penis is shrinking and will retract into the abdomen and cause death.DELUSIONS: false, unshakable belief that is out of keeping with the patients social and cultural background.Special types:i COTARD S SYNDROME: extremely severe nihilistic delusion. Seen in severe depression. Eg: patient complains that their bowels have been destroyed and may never pass feces again.ii CAPGRAS SYNDROME: patient believes that a person closely related to her has been replaced by a double.iii FREGOLI SYNDROME: the patient believes that one or more people have changed their appearance to resemble familiar people, usually in order to persecute the patient.iv INTERMETAMORPHOSIS : patient believes that a person persons have been transformed, both physically and psychologically into another person that people have exchanged identities with each other.v Doppelganger: patient has delusion that another person has been physically transformed into his own self syndrome of subjective doubles.vi FOLIE A BEUX: person in a close relationship with somebody who already has an established delusional system develops similar ideas shared induced delusional disorder. 