Visual Memory Deficits: A Plausible Cause of Developmental Dyslexia? Evidence from a Single Case Study

Abstract

This paper presents the case of JAS, a developmental dyslexic who had largely resolved her reading problems as an undergraduate student. However, testing revealed that JAS had subtle reading deficits, having difficulty with low-frequency irregular words and with the comprehension of written homophones. In contrast, her phonological reading strategies were normal. JAS's reading deficit was accompanied by serious spelling problems; she showed a marked tendency to spell phonologically, although with reference to some word-specific knowledge.

JAS's reading and spelling difficulties were accompanied by significant visual memory deficits although phonological processing was relatively good. It is argued that visual memory impairments have prevented JAS from establishing detailed orthographic representations in a lexical system. In the absence of these, the operation of the system for reading is faulty; for spelling, which requires die use of full orthographic cues, there are serious consequences.