Page:Popular Science Monthly Volume 70.djvu/162

158 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 understanding 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 leaving out different forms of the same root word (e. g., photograph, photographer). 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 dictionary (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 dictionary. 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 fundamentally 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 numbered 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 auditory 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