Reading and a Diffusion Model Analysis of Reaction Time

Abstract

Processing speed is associated with reading performance. However, the literature is not clear either on the definition of processing speed or on why and how it contributes to reading performance. In this study we demonstrated that processing speed, as measured by reaction time, is not a unitary construct. Using the diffusion model of two-choice reaction time, we assessed processing speed in a series of same–different reaction time tasks for letter and number strings. We demonstrated that the association between reaction time and reading performance is driven by processing speed for reading-related information, but not motor or sensory encoding speed.

ACKNOWLEDGMENT

The authors express sincere gratitude to Mr. Stephen Katz for programming the experimental procedures and managing the initial database, a team of research assistants who collected the data, and to Ms. Robyn Rissman and Ms. Mei Tan for their editorial assistance.

This work was supported by a grant from the International Dyslexia Association (PIs: E. Grigorenko and L. Katz), by grants NICHD01994 (PI: C. Fowler), DC007665 (PI: E. Grigorenko), HD048830 (PI: K. Pugh), HD052120 (PI: R. Wagner), MH18268 (PI: J. Leckman), and MH081756 (PI: F. Volkmar) from the National Institutes of Health. Grantees undertaking such projects are encouraged to freely express their professional judgment. This article, therefore, does not necessarily represent the position or policies of the IDA or the NIH, and no official endorsement should be inferred.