The characteristic symptoms of schizophrenia have been classified into three broad categories: positive, negative, and disorganized. Positive symptoms include delusions and hallucinations. Negative symptoms include decreased thought and speech productivity (alogia), loss of ability to experience pleasure (anhedonia), decreased initiation of goal-directed behavior (avolition), and speech with little or no change to their tone, little or no change in their facial expression, even if they are talking about something upsetting or exciting (affective flattening). Disorganized symptoms include disorganized speech (frequent derailment and incoherence), and disorganized behavior and attention.