Mentalisation: ‘mind-mindedness’, the ability to see ourselves as others see us, and others as they see themselves; to appreciate that all human experience is filtered through the mind and therefore that all perceptions, desires and theories are necessarily provisional. Psychotherapy, whether cognitive or psychoanalytic, aims to enhance mentalisation skills and to identify situations in which mentalisation is impaired. Mentalisation and arousal are inimical – stress interferes with the ability to mentalise effectively. Stressed non-mentalising psychiatrists and their patients, especially those with borderline personality disorder, are less likely to make good decisions than their mentalising counterparts. Training helps overcome this.