APA Dictionary of Psychology

a form of cycloid psychosis in which disturbances of cognitive processes are prominent and accompanied by a labile (highly changeable) emotional state characterized alternately by manifest anxiety, with the individual often misidentifying other people, and by mutism and greatly decreased movement. The latter differs from catatonic stupor in that self-care and spontaneity are preserved and negativism is absent. [defined by German psychiatrist Karl Leonhard (1904–1988)]