Although composed of similar elements and structured similarly, the communications systems associated with the physical sciences and the social sciences differ markedly with respect to the operation and use of these elements. For both groups of disciplines, as information flows through the system it encounters lags and filtering, and much of a scientist's communication behavior is an effort to compensate for these factors. Because the lags and filtering within each system differ in loci and extent, the members of different disciplines adjust to them differently, and the overall information flow patterns in the physical and in the social sciences differ.