g. High frequency word list/low density
The work of Morrisette & Gierut (2002), Morrisette (1999) and Storkel & Morrisette (2002) identified two lexical properties, frequency and density, that interact with phonology. First, treating high-frequency words created more change in a child’s system than low-frequency words. Second, these studies identified the target of word density, or the number of words that differ from a target word by one sound through substitution, addition or deletion. For example, the word “sound” has ten neighbors that differ by one sound, such as “found,” “send” and “sounds.” These studies categorized words with ten or fewer neighbors as low-density and those with eleven or higher as high-density. Different treatment effects were observed for each category. Low density tended to impact the treated sound(s) while high density impacted untreated sounds or contexts. In order to apply these principles, SLPs can download a document entitled High Frequency Word List at: http://slpath.com/highfrequencywordlist.html. This resource was created based on the database of Dr. Larry Sommers at Washington University in St. Louis (http://128.252.27.56/neighborhood/Home.asp)(n.d.) and is organized by sounds (and often word position). Two numbers follow each target word. For instance, the first word is “race” following by the numbers 103 and 29. 103 indicates that “race” is a high frequency word. (According to the database, any word that occurs 100 or more times out of one million is deemed high-frequency. All words in the resource fall into this category.) 29 refers to the number of neighbors or counterparts “race” has, making it a high-density word.