What are the clinical characteristics of Schizophrenia?

When looking at the clinical characteristics of schizophrenia, some psychologists make a distinction between positive and negative symptoms of schizophrenia. Positive symptoms are those showing an excess or distortion of normal functioning (hallucinations, delusions, experiences of control and disordered thinking). Negative symptoms are those reflecting a loss of normal functioning (disturbances of affect (emotions), alogia and avolition)+ Hallucinations: bizarre, unreal perceptions of the environment. They are usually auditory in the form of hearing voices but can be visual, smelling or taste.+ Delusions: false beliefs that seem real to the person that remain even in the presence of disconfirming evidence. + Experiences of control: individual may believe that they are under the control of an external force that has invaded their mind/body e.g. aliens/government. + Disordered thinking: involves thought disturbances; either believing thoughts have been inserted or withdrawn by someone else or that thoughts are being broadcasted to others. It also involves problems with thought processes; not being able to maintain focus and attention in thought (indicated by loosely connected speech). - Disturbances of affect (emotions): involve flattened effect (reduction in the range and intensity of emotional expression) and inappropriate effect (displaying emotions inappropriate to the situation). - Alogia: poor speech; i.e. breaks in trail of thought leads to incoherent speech. Alogia may also urge neologism (made up words). - Avolition: the individual has no motivation to initiate or persist in goals, e.g. sits around for hours doing nothing.