Fig. 3 Spectral sensitivity of human cones measured by the suction electrode technique. Average of five L cones (left) and a single M cone (right). The solid lines are derived from macaque monkey cones using the same technique. (Reprinted with permission from Schnapf JT, Kraft TW, Baylor DA: Spectral sensitivity of human cone photoreceptors. Nature 325: 439, 1987. Copyright 1987, Macmillan Magazines Ltd.)