Hallucinations occur when a person experiences a sensory stimulus, which they perceive as real but which has not actually occurred. For example, auditory hallucinations occur when the person has the experience of hearing a voice or voices when in fact nobody has spoken. Visual hallucinations occur when the person sees something which is not there in reality. The experience how ever, is totally 'real' to the person. Schizophrenia also impacts on a person's ability to establish and maintain friendships and to remain in school or employment.