A Computerized Measure of Idea Density in Two Genres of Written Language

Abstract

This study investigates a linguistic measure known as idea density (ID) calculated from two different genres of written language samples. ID has been previously used in research pertaining to language and aging and has been shown to have predictive validity for cognitive decline and severity of Alzheimer’s neuropathy (e.g. Snowden et al., 1996); however, little is known about ID, including how it may differ between different types of language genres and how it correlates with vocabulary and level of education. This study compares ID of narrative and expository texts generated by young adults to provide preliminary information regarding the relationship between genre type and ID. It also explores the relationship between ID and various measures of academic achievement and vocabulary. In this study, ID was calculated by the Computerized Propositional Density Rater version 5.1 (CPIDR 5.1) (Brown et al., 2012) software. The results of this study found mean ID for personal narrative texts to be significantly greater than mean ID for expository texts; however, results suggest little correlation between ID and education level or vocabulary skill. These results suggest that, as research utilizing ID continues to expand, researchers should consider the potential presence of a genre effect when determining methods for elicitation of a language sample for ID analysis. Results are in line with other literature suggesting that ID is measuring aspects of linguistic functioning separate from those used to attain academic success. A discussion of ID in relation to genre effects, cognitive reserve hypothesis, and implications for future research is included.