Bleuler, Eugen /bloi″lər/ [Swiss psychiatrist, 1857–1939] , a pioneer investigator in the fields of autism and schizophrenia. Bleuler introduced the term schizophrenia to replace dementia praecox and identified four primary symptoms of schizophrenia, known as Bleuler’s “4 A’s”: ambivalence, associative disturbance, autistic thinking, and affective incongruity.