9. Write brief explanations of the following terms: practice habit higher unit overlapping plateau physiological limit insight trial and error negative adaptation substitute stimulus substitute response conditioned reflex {331} REFERENCES Thorndike's _Animal Intelligence, Experimental Studies,_ 1911, reports his own pioneer work in this field. See also Chapter X in the same author's _Educational Psychology, Briefer Course_, 1914. For other reviews of the work on animal learning, see Watson's _Behavior_, 1914, pp. 184-250; also Washburn's _Animal Mind_, 2nd edition, 1917, pp. 257-312. For human learning and practice, see Thorndike's _Educational Psychology, Briefer Course_, 1914, Chapters XIV and XV; also Starch's _Educational Psychology_, 1919, Chapter XI. For an experiment showing the acquisition of fears by a child, see Watson and Raynor, "Conditioned Emotional Reactions", in the _Journal of Experimental Psychology_, 1920, Vol. 3, pp. 1-14. James's chapter on "Habit", in his _Principles of Psychology_, 1890, Vol. I, is a classic which every one should read. {332} CHAPTER XIV MEMORY HOW WE MEMORIZE AND REMEMBER, AND IN WHAT RESPECTS MEMORY CAN BE MANAGED AND IMPROVED So much depends on a good memory in all walks of life, and especially in brain work of any sort, that perhaps it is no wonder that many students and business and professional men become worried about their memories and resort to "memory training courses" in the hope of improvement. The scientific approach to this very practical problem evidently lies through a careful study of the way in which memory works, and the general problem may be expressed in the question, how we learn and remember. This large problem breaks up, on analysis, into four subordinate questions: how we commit to memory, how we retain what has been committed to memory, how we get it back when we want it, and how we know that what we now get back is really what we formerly committed to memory. In the case of a person's name which we wish to remember, how do we "fix it in mind", how do we carry it around with us when we are not thinking of it, how do we call it up when needed, and what assures us that we have called up the right name? The four problems may be named those of (1) Memorizing, or learning, (2) Retention (3) Recall (4) Recognition {333} The Process of Memorizing