<prompt> Illusion is:A false unshaken belief not keeping ones sociaocultural backgroundPerception without stimuliAbnormal perception by a sensory misinterpretation of actual stimulusFear of closed spaces  <response>: Illusion is an abnormal perception caused by a sensory misinterpretation of actual stimulus, sometimes precipitated by strong emotion, e.g. fear provoking a person to imagine they have seen an intruder in the shadows. REF : Oxford text book of psychiatry 3rd Ed. 