An elliptically polarized laser beam tuned to the D1 transition of atomic sodium is sent through a vapor of sodium atoms that has been collisionally broadened by a buffer gas. The beam, initially Gaussian, is observed to break up into a narrower, pure circularly polarized spot surrounding an annulus of the opposite circular polarization. The sense of circular polarization of the central output spot corresponds to the weaker polarization component of the input field, and the polarization of the annular output beam corresponds to the stronger polarization component of the input field. A detailed comparison is made between the behavior observed and a recently developed theory of self-induced spatial separation of circularly polarized components.