Positive symptoms in primary psychotic transtornos include persistent delusions, persistent hallucinations (most commonly verbal auditory hallucinations), disorganised thinking (formal thought transtorno such as loose associations, thought derailment, or incoherence), grossly disorganised behaviour (behaviour that appears bizarre, purposeless and not goal-directed) and experiences of passivity and control (the experience that one's feelings, impulses, or thoughts are under the control of an external force). The rating should be made based on the severity of positive symptoms during the past week.