Single-route and dual-route approaches to reading aloud difficulties associated with dysphasia.

Abstract

The study of reading aloud is currently informed by two main types of theory: modular dual-route and connectionist single-route. One difference between then theories is the type of word classification system which they favour. Dual-route theory employs the regular-irregular dichotomy of classification, whereas single-route considers body neighbourhoods to be a more informative approach. This thesis explores the reading aloud performance of a group of people with dysphasia from the two theoretical standpoints by employing a specifically prepared set of real and pseudoword stimuli. As well as being classified according to regularity and body neighbourhood, all the real word stimuli were controlled for frequency. The pseudowords were divided into two groups, common pseudowords and pseudohomophones, and classified according to body neighbourhood.

There were two main phases to the study. In the first phase, the stimuli were piloted and the response time performances of a group of people with dysphasia and a group of matcehd control people were compared. In the second phase, a series of tasks was developed to investigate which means of word classification best explained the visual lexical decision and reading aloud performance of people with dysphasia. The influence of word knowledge was also considered.

The data was analysed both quantitatively and qualitatively. The quantitative analysis of the number of errors made indicated that classification of items by body neighbourhood and frequency provided the more comprehensive explanation of the data. Investigation of the types of errors that were made did not find a significant relationship between word type and error type, but again the results indicated that the influence of frequency and body neighbourhood was stronger than that of regularity. The findings are discussed both in terms of their implications for the two theories of reading aloud and their relevance to clinical practice.