Reading Ability: Lexical Quality to Comprehension

The lexical quality hypothesis (LQH) claims that variation in the quality of word representations has consequences for reading skill, including comprehension. High lexical quality includes well-specified and partly redundant representations of form (orthography and phonology) and flexible representations of meaning, allowing for rapid and reliable meaning retrieval. Low-quality representations lead to specific word-related problems in comprehension. Six lines of research on adult readers demonstrate some of the implications of the LQH. First, large-scale correlational results show the general interdependence of comprehension and lexical skill while identifying disassociations that allow focus on comprehension-specific skill. Second, word-level semantic processing studies show comprehension skill differences in the time course of form-meaning confusions. Studies of rare vocabulary learning using event-related potentials (ERPs) show that, third, skilled comprehenders learn new words more effectively and show stronger ERP indicators for memory of the word learning event and, fourth, suggest skill differences in the stability of orthographic representations. Fifth, ERP markers show comprehension skill differences in meaning processing of ordinary words. Finally, in text reading, ERP results demonstrate momentary difficulties for low-skill comprehenders in integrating a word with the prior text. The studies provide evidence that word-level knowledge has consequences for word meaning processes in comprehension.