158 POPULAR SCIENCE MONTHLY 



so nearly the same as to convince me that the method was fairly 

 accurate. Some preliminary tests were then made that showed that 

 a hundred words taken by chance from various parts of the dictionary 

 might serve as a fairly accurate measure of the size of one's understand- 

 ing vocabulary. The words used in the final test consisted of fifty 

 words taken from the first four words on every fiftieth page of Webster's 

 academic dictionary and fifty words from the first of other pages leav- 

 ing out different forms of the same root word (e. g., photograph, photog- 

 rapher). This was done with the thought that older persons might 

 be able to infer better the meaning of unfamiliar words than younger 

 persons. The results were negative and the author now considers 

 that the best list of words is obtained from Webster's academic dic- 

 tionary (which contains about 28,000 words on 645 pages), by taking 

 the first, second, or last word, or any other definite word on every sixth 

 page. For general purposes and for all ages this is probably better 

 than to take a hundred words from an unabridged dictionary which 

 contains so many various and obsolete forms of the same words, along 

 with rare words, and technical terms not found in the smaller dic- 

 tionary. Estimates based on words from the academic dictionary give 

 less than half as many words in the vocabulary as those based on 

 data from the unabridged, but they are more representative of funda- 

 mentally different concepts. 



The method of using the test was to place the printed list before 

 the subjects and ask them to mark the words that they knew with a 

 plus (-{-) sign, those that they did not know with a minus ( — ) sign, 

 and doubtful ones with a question mark (?). The tests which num- 

 bered about two thousand were made chiefly upon pupils from the 

 fourth grade up through the high school and university, although a few 

 were made upon younger children. Control tests showed that if the 

 same test was given orally, there was some difference in the words 

 marked as known and unknown. This difference was of course very 

 great in the second and third grades, where a few tests were made, 

 and became less with age, yet it usually amounted even in the case 

 of adults to from one to three per cent. In a few individuals the 

 difference was quite marked. 



The reason for this is that some words are more often heard than 

 others, while others are more often seen, hence in one case the audi- 

 tory stimulus arouses familiar associations while in the other case the 

 visual stimulus is more effective. In general the auditory stimulus" 

 is more effective for children, but, as they read more, the visual stimulus 

 becomes more effective and later many words are seen that are rarely 

 or never heard; hence for such words the visual stimulus is the most 

 effective and sometimes the only stimulus which will produce the 

 reaction of familiarity. The test is more accurate if both forms of 



