7. Memorizing a series of related words. Prepare a list of 40 words, as follows: first write the numbers 1 to 40 in a column; then write any word for No. 1; for No. 2, write some word closely related to No. 1; for No. 3 some word closely related to No. 2; and so on. Your list, for example, might begin like this: house, roof, chimney, soot, fire, coal, mine, miner, strike, arbitration, etc. Having finished writing your list, cover it and see how much of it you can recite without further study, and how long it takes you to complete the memorizing. Explain the results obtained. 8. Plot the curve of forgetting from the following data, which give the per cent, of retention of stanzas of a poem at different intervals after the end of memorizing. after 1 day 79% after 2 days 67% after 6 days 42% after 14 days 30% after 30 days 24% REFERENCES Ebbinghaus, _On Memory_, 1885, translated by Ruger and Bussenius, 1918. This is the pioneer experimental study of memory, and is still worth reading, and is not specially hard reading. James's chapter on Memory, in Vol. I of his _Principles of Psychology_, 1890, is still one of the best references, and contains some important remarks on the improvement of memory. Of the numerous special studies on memory, mention may be made of that by Arthur I. Gates, _Recitation as a Factor in Memorizing_, 1917, which, on pp. 65-104, gives a valuable account of the various devices used by one who is memorizing. For the psychology of testimony, see G. M. Whipple's article on "The Obtaining of Information: Psychology of Observation and Report", in the _Psychological Bulletin_ for 1918, Vol. 15, pp. 217-248, especially pp. 233-248. See also a popularly written account of the matter by Münsterberg, in _On the Witness Stand_, 1908, pp. 15-69. {366} CHAPTER XV ASSOCIATION AND MENTAL IMAGERY SOMETHING ABOUT THINKING AS RELATED TO MEMORY