Vocabulary skills are well developed in university students with dyslexia: Evidence from multiple case studies

Most studies in adults with developmental dyslexia have focused on identifying the deficits responsible for their persistent reading difficulties, but little is known on how these readers manage the intensive exposure to written language required to obtain a university degree. The main objective of this study was to identify certain skills, and specifically vocabulary skills, that French university students with dyslexia have developed and that may contribute to their literacy skills. We tested 20 university students with dyslexia and 20 normal readers (matched on chronological age, gender, nonverbal IQ, and level of education) in reading, phonological, vocabulary breadth (number of known words), and vocabulary depth (accuracy and precision) tasks. In comparing vocabulary measures, we used both Rasch model and single case study methodologies. Results on reading and phonological tasks confirmed the persistence of deficits in written word recognition and phonological skills. However, using the Rasch model we found that the two groups performed at the same level in the vocabulary breadth task, whereas dyslexics systematically outperformed their chronological age controls in the vocabulary depth task. These results are supplemented by multiple case studies. The vocabulary skills of French university students with dyslexia are well developed. Possible interpretations of these results are discussed.