What are positive and negative symptoms of schizophrenia?

A classification: An attempt to differentiate patients based on predominant symptoms. Positive are delusions and hallucinations and are thought to denote those with a better response to treatment. Negative symptoms include withdrawal, flat affect, poverty of speech, poor hygiene or grooming, low motivation, and anhedonia. These make the patient less accessible to any therapy and are less responsive to medication.

Definitions: Positive symptoms are additional experiences, such as hallucinations and delusions added to a person's perception of reality. Negative symptoms represent a lack of what should be there, i.e. Motivation, drive, desire for human interaction and conversation.