“…First, some data already show both direct and inverse relations between responding and reward density within the same type of feeding economy (e.g., Allison, 1981;Atnip, 1986;Baum, 1981;Brandauer, 1958;Green, Kagel, & Battalio, 1982Hanson & Timberlake, 1983;Hogan & Roper, 1978;Hursh, 1984;Peden & Timberlake, 1984;Staddon, 1979;Timberlake, 1977Timberlake, , 1980. Second, open and closed economies usually differ in terms of a number of dimensions in addition to supplemental feeding and the relation between responding and intake.…”