Bizarre behavior may take the form of childlike silliness, agitation, or inappropriate appearance, hygiene, or conduct. Catatonic motor behavior is an extreme form of bizarre behavior in which a person may maintain a rigid posture and resist efforts to be moved or, in contrast, display purposeless and unstimulated motor activity. Deficit or negative symptoms of schizophrenia include blunted affect, poverty of speech, anhedonia, and asociality. Blunted affect refers to a flattening of emotions. Events that would normally make a person laugh or cry produce no response.
Poverty of speech refers to a diminishment of thoughts reflected in a decreased amount of speech.
Answers to questions may be terse, one or two words, creating the impression of an inner emptiness. Asociality refers to a lack of interest in relationships with other people. These negative symptoms are often associated with a general loss of motivation, sense of purpose, and goals. Subtypes of schizophrenia have been proposed in an effort to classify patients into more uniform groups. However, among individual patients, the subtype may change over time.