PSYCHOLOGY 



XXXI. A BOY'S VOCABULARY AT EIGHTEEN 



MONTHS 



Geo. F. Miller, Margaret D. Miller and Margaret M. Nice* 



Norman, Oklahoma 



In any study of natural phenomena it is important to have in- 

 stances of the limits of variation. In the matter of speech develop- 

 ment careful studies should be made of children who are slow in 

 beginning to speak and also of some who are markedly precocious, 

 besides of the more normal cases. It is for the purpose of augment- 

 ing our knowledge as to the possibilities with a young child in the 

 way of large vocabularies that we are. offering the present record. 



Duncan Miller is the oldest son of two college teachers, his 

 father being a psychologist and his mother a specialist in languages. 

 As to physical development, he is large for his age, having weighed 

 8^ pounds at birth, 2S pounds at one year and 27 pounds at 18 

 months. Except for severe colic during the first two months of 

 his life, he has enjoyed excellent health. He walked at the early 

 age of 11 months. 



On his second brithday he was given the Binet test by his 

 father and scored an I.Q. of 166. He passed all the three year 

 tests but that of knowing his sex ; he repeated the digits and passed 

 the comprehension test of four years, while for the fifth year he 

 gave the definitions. 



A chronological list of the words used by Duncan was kept by 

 his mother through his thirteenth month, but the dates of new 

 acquisitions were not always recorded. At this time both parents 

 began to keep track of the rapidly increasing vocabulary in a very 

 systematic mnner, i. e., each new word was written on a card with 

 the date, all the cards being filed alphabetically. 



The first word "tick-tick" was spoken at the age of eight and 

 a half months. The first sentence "Man scold" was used at 15 

 months and the first complex sentence at 20 months — "Broke the 

 cup that had the flowers on it." The order of appearance of the 

 parts of speech was as follows: nouns, 8 months; interjections, 12; 

 verbs and adjectives, 13; adverbs, 14; pronouns, 16; prepositions, 17 

 and conjunctions 20 or 21 months. 



The vocabulary follows, the words being arranged chronologi- 

 cally under each part of speech. The pronunciation is not indicated 

 after the 13th month. N. W. means new words ; T. W. means 

 total words. 



*Tlie vocabulary was collected by the first two authors and the material 

 prepared for publication by the third. 



