At 27 days the active animals were significantly better than the passive animals on the initial test
in Richard D. Walk Papers, of University of Akron. Cummings Center for the History of Psychology; with Richard David Walk, 1920-1999, Series Four: Research Files, 1945-1997. Subseries One: Visual Cliff Research, 1958-1996, Box M4928, Folder 2: Visual cliff data - kittens, 1960-1968 , 23 page(s)
