Research studies on dyslexia: participant inclusion and exclusion criteria

ABSTRACT

Dyslexia is a term widely used to describe reading characterised by problems with the fluent and accurate letter or word recognition. Nevertheless, there is no consensus about the definition, origin, and diagnosis of dyslexia and the term is often used very differently by researchers and practitioners. In many cases, research findings are employed by clinicians in ways that are misleading and potentially counterproductive. The present study takes the form of an examination of participant samples included in studies of dyslexia (n = 800) over 20 years (2000–2019). The findings show that (1) researchers use a wide range of inclusion and exclusion criteria; that (2) IQ-reading achievement discrepancy is the most common inclusion criterion for dyslexia samples; (3) studies typically compare dyslexic samples to normal controls but not to other poor readers; (4) dyslexia seems to be employed as a catch-all term for poor readers in general, not as a term to define a specific type of poor reader. Finally, (5) dyslexia studies are very rarely published in educational journals.

KEYWORDS:

• Dyslexia
• poor readers
• sample constitution
• inclusionary criteria
• exclusionary criteria

Disclosure statement

No potential conflict of interest was reported by the authors.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Notes

1. An Excel file containing the complete data set can be found at https://www.dropbox.com/s/b3j0u2ldmo0wsdl/2000-2019.xlsx?dl=0.

Additional information

Notes on contributors

João A. Lopes

João A. Lopes holds a Ph.D. in Psychology, and he is a hired Professor in the School of Psychology of the University of Minho. His research interests focuses in the areas of learning disabilities, reading instruction, classroom behavior problems and classroom management. He wrote more than a dozen books on these subjects.

Cristina Gomes

Cristina Gomes is an Educational Psychologist. She holds a Master degree in Psychology from the University of Minho. She is a member of the “Learning and Behavior Problems Research Group” at the University of Minho where she has been actively involved in the project of samples constitution in dyslexia studies. Shis is also a Chartered Educational Psychologist.

Célia R. Oliveira

Célia R. Oliveira holds a PhD in Experimental Psychology and Cognitive Sciences from the University of Minho. She is Assistant Professor at Lusófona University of Porto, where she is responsible for course units in the field of Cognition (Attention and Memory) and of School and Educational Psychology. Her research has been focused in the fields of jearning and human memory, teaching in elementary education, and classroom indiscipline. She also has been carried out scientific consultancy in research projects, alongside with intervention and technical consultancy in educational issues.

Julian G. Elliott

Julian G. Elliott is Principal of Collingwood College, and Professor of Educational Psychology, at Durham University. He is a Fellow of the Academy of Social Sciences, a Chartered Psychologist, and an Associate Fellow of the British Psychological Society. One of his recent books (co-authored with Rod Nicolson), Dyslexia: Developing the Debate. London: Bloomsbury Press, 2016, follows on from his earlier The Dyslexia Debate, co-authored with Elena Grigorenko (Cambridge University Press, 2014).