The most common category of PSYCHOSIS and one which covers a wide variety of symptoms and BEHAVIOUR. The term schizophrenia comes from the Greek words schizo (split) and phrenia (mind) and this is the source of an almost universal popular misconception. Split mind (or SPLIT PERSONALITY) is the popular term for MULTIPLE PERSONALITY, in which the split occurs between what appear to be different personalities within the same person. The split in schizophrenia however is between the processes of thinking and feeling within the same person, so that the harmony normally found between a person's thought, feelings and actions is disrupted. A schizophrenic may smile or show no EMOTION at all when discussing a tragic event, for instance. Difficulties in communication with others. DELUSIONS and HALLUCINATIONS are also common symptoms of schizophrenia.