A chronic stage in the development of a schizophrenic illness in which there has been a clear progression from an early stage to a later stage characterized by long- term, though not necessarily irreversible, "negative" symptoms, e.g. psychomotor slowing; underactivity; blunting of affect; passivity and lack of initiative; poverty of quantity or content of speech; poor nonverbal communication by facial expression, eye contact, voice modulation and posture; poor self-care and social performance.