Concreteness Effects in Word Production but Not Word Comprehension in Deep Dyslexia

Abstract

We present a patient, LW, who, like all deep dyslexics, is more able to read aloud concrete than abstract words. In order to explore the cause of this concreteness effect in word production, we tested LW's comprehension of concrete and abstract words, in the Shallice and McGill word-picture matching task, in a synonym judgement task, and in a definition-to-word matching task. LW showed no significant impairment of her comprehension of abstract high-frequency words in these tasks, despite being unable to read most of the words aloud. We conclude that the concreteness effect in oral reading in LW cannot be due solely to a semantic deficit for abstract words. We propose the NICE model, in which concreteness is an important dimension of normal lexicalisation, and suggest that deep dyslexia reflects the ability of qualitatively normal but isolated semantics to access or “drive” unique entries in a phonological output lexicon subject to a pathological increased aphasic “threshold” for lexicalisation.