The New Final Definition of Dyslexia released by SASC

Understanding Dyslexia: A New Expert Consensus

Dyslexia is one of the most well-known learning difficulties, yet there is still confusion about what it really means. Over the years, different definitions have led to mixed messages for parents, teachers, and even professionals. A recent Delphi study, carried out by leading dyslexia researchers, aimed to bring clarity by gathering expert opinions and agreeing on a definition that reflects the latest understanding of dyslexia.

What is a Delphi Study?

A Delphi study is a research method used to gather expert opinions and reach an agreement on complex topics. In this study, a panel of academics, specialist teachers, educational psychologists, and individuals with dyslexia reviewed statements about dyslexia over several rounds, refining them until they reached at least 80% agreement.

What Did the Experts Agree On?

The study confirmed that dyslexia is a difficulty with reading and spelling that varies in severity and persists throughout life.

Key points from the expert panel:

• Dyslexia is a neurodevelopmental condition, meaning it is present from birth and affects how the brain processes language.

• Reading fluency and spelling difficulties are the most consistent signs of dyslexia across different languages.

• Phonological difficulties (challenges recognising and working with sounds in words) are a common feature, but other factors like working memory, processing speed, and recognising spelling patterns can also contribute.

• Dyslexia frequently co-occurs with other learning differences, such as ADHD, developmental language disorder (DLD), and dyscalculia (difficulty with maths).

• Dyslexia is not related to intelligence—it affects people across all ability levels.

Moving Away from the ‘IQ Discrepancy’ Model

In the past, dyslexia was diagnosed based on a gap between reading ability and IQ. However, experts now agree that dyslexia can affect individuals of all intelligence levels and should not be defined by a discrepancy between ability and achievement. Instead, it is better understood as a specific difficulty with literacy that persists despite good teaching and learning opportunities.

Dyslexia is a Lifelong Condition

Dyslexia is not something children "grow out of." While interventions can improve reading and spelling, many people with dyslexia continue to struggle with reading fluency, spelling, and written work throughout their lives. This is why ongoing support and adjustments are crucial, even when reading skills improve.

Addressing Common Myths About Dyslexia

The study also tackled some misconceptions about dyslexia:

• Dyslexia is not caused by vision problems or ‘visual stress’. While some people with dyslexia experience visual discomfort when reading, these issues are separate and should not be confused with dyslexia.

• Dyslexia does not automatically mean a person is more creative or has special talents. Some individuals develop strengths in creative areas, but there is no strong scientific evidence that dyslexia gives people an advantage in visual-spatial or artistic skills.

A Clearer Definition of Dyslexia

Based on the study, the experts proposed a new definition of dyslexia that:

1. Describes dyslexia as a processing difficulty that affects the development of reading and spelling skills.

2. Recognises that dyslexia exists on a spectrum, meaning it can be mild, moderate, or severe.

3. Acknowledges that multiple genetic, cognitive, and environmental factors influence dyslexia.

4. Confirms that dyslexia often occurs alongside other learning differences.

5. Emphasises that reading fluency and spelling difficulties remain challenges throughout life, even when reading accuracy improves.

What This Means for Assessments and Support

Experts stress that dyslexia assessments should take a developmental approach, considering factors such as family history, phonological difficulties, and response to intervention. The study also highlights that all individuals struggling with literacy should receive appropriate support, whether or not they have a formal diagnosis of dyslexia.

Final Thoughts

By bringing together research and real-world experience, this study helps to clarify what dyslexia is and how it should be identified and supported. The findings provide an updated, research-backed understanding of dyslexia, which can help parents, teachers, and professionals ensure that children and adults with dyslexia get the right help at the right time.

Source: Carroll, J. M., Holden, C., Kirby, P., Thompson, P. A., Snowling, M. J., & the Dyslexia Delphi Panel. (2025). Toward a consensus on dyslexia: Findings from a Delphi study. Journal of Child Psychology and Psychiatry. doi:10.1111/jcpp.14123