What is dyslexia and how does it affect learning?

Dyslexia is a specific learning difficulty primarily affecting the accuracy and fluency of word reading and spelling. It is neurological in origin, persists across the lifespan, and is unrelated to intelligence — which is the most important thing to state, because the historical framing as laziness or low ability caused enormous harm.

The core difficulty is generally understood as phonological processing — difficulty perceiving, remembering and manipulating the sound structure of language. Mapping letters to sounds, blending them and doing so automatically requires this, and when it is impaired, reading remains effortful long after peers have automated it.

Rapid automatised naming — quickly retrieving names for familiar items — is also commonly affected and is a strong early predictor.

What it looks like:

Slow, effortful reading with inaccurate decoding of unfamiliar words.

Persistent spelling difficulty, often inconsistent for the same word.

Working memory demands. Because decoding consumes effort, less capacity remains for comprehension — a reader may decode a sentence and retain nothing, which is exhausting and easily mistaken for inattention.

Difficulty with sequences — alphabet, times tables, months, instructions in order.

Slow writing and copying, and difficulty taking notes while listening.

Fatigue, since sustained reading is genuinely more tiring.

What it is not. It is not primarily a visual problem, and the widespread belief that letters visibly move or reverse is largely a misconception. Coloured overlays and tinted lenses are not supported by good evidence, despite continuing popularity.

What does help, with evidence:

Structured, systematic phonics taught explicitly, intensively and cumulatively — the best-supported intervention, and more effective earlier.

Assistive technology — text-to-speech, speech-to-text, audiobooks, spellcheckers. These are not shortcuts; they separate the reading difficulty from the learning.

Extra time and reasonable adjustments in assessment.

Not penalising spelling where the assessment is of subject knowledge.

It frequently co-occurs with dyspraxia, ADHD and dyscalculia.