This is the third published report of the annual symposium on cybernetics sponsored by the Josiah Macy, Jr. Foundation. Eight conferences have been held but the transactions of only the last three have been published. Cybernetics (a name devised by Norbert Weiner) designates a mode of investigation of biological behavior with the aid of concepts derived from the mathematical and physical approaches to the understanding of group, causal and controlled phenomena. It is not a well demarcated field and, in general, is more or less coextensive with the interests of its founders which include Norbert Weiner, Arturo Rosenblueth, Warren McCulloch, Lawrence S. Kubie, Walter Pitts, John Von Neumann and Claude Shannon. One of the most important and earliest interests of this group is the study of the logical principles underlying the construction of electronic and mechanical computing machines and the applications of such principles for furthering understanding of intellectual