It also surfaces in the genteel purlieux of Lorrie Moore's recent collection of stories, Birds of America. Somebody stares "at her own reflection: in an attempt at extroversion, she had worn a tunic with large slices of watermelon depicted on the front".
It is a logical develop- ment from the adjective extrovert, but little used in England. Originally, in the 17th century, it had a religious, mystical connotation, and acquired its psychological tang in the 1920s, but the OED last notes its use in 1959. Lorrie Moore would surely add local colour to the entry.