[ 9]. C.S. Myers, M.D., An Introduction to Experimental Psychology, chap. V, p. 73.
[10]. G.M. Stratton, Experimental Psychology and Culture, p. 125.
[11]. William James, Psychology, Briefer Course, p. 171.
[12]. F.B. Gilbreth, Bricklaying System, chap. I, Training of Apprentices.
[13]. McClure's Magazine, May, 1911, Dec, 1911, Jan., 1912.
[14]. As a woodman's keenness of hearing.
[15]. M.W. Calkins, A First Book in Psychology, chap. III.
[16]. Stratton, Experimental Psychology and Culture, chap. VII.
[17]. Compare with an actor's learning a part.
[18]. As proved by experimenting with a six-year-old child.