Science of reading

Reading models

Since the purpose of reading is to understand what we read, it is necessary to teach reading comprehension skills. However, it is important to recognize that decoding is a precursor skill to understanding.

Decoding/word recognition is the ability to accurately and quickly read the words on a page and it plays a critical role in reading comprehension.

When a child struggles with decoding, fluency is decreased, accuracy is compromised, errors occur, and the energy needed for comprehension is depleted by the effort required to simply decode.

The Simple View of Reading

Gough & Tunmer (1986) proposed the widely accepted view that reading comprehension (R) has two basic components: word-level decoding ability (i.e. word recognition) (D) and listening/oral language comprehension ability (C) (i.e. how well one understands spoken language) (Figure 1). It is called the ‘Simple View of Reading’ (Farrell et al 2010, Wren 2001).  Good readers have strong abilities in both components of reading.  If decoding or language comprehension is poor, then reading comprehension will be affected.

Figure 1 The Simple View of Reading

Gough & Tunmer (1986)

Simple View of Readingc2

The Simple View of Reading has been tested in over 100 studies (see Kilpatrick 2015 p. 47 for further discussion) and endorsed by many reading experts (eg. Linda Farrell & colleagues at the Center for Development & Learning (2010)).

Other investigators have further developed the Simple View of Reading by elaborating on the cognitive foundations of decoding (D) and listening comprehension (C). Wren (2001) elaborates that decoding ability (D) is a function of knowledge of print concepts, letter knowledge, phoneme awareness and knowledge of the alphabetic principle (linking letters with sounds) (Wren, 2001). Scarborough also includes sight recognition of familiar words (eg. fluency) (Scarborough, 2001). Listening/language comprehension (C) is a function of background knowledge, phonology, syntax, and semantics (Wren, 2001); Scarborough (2001) also includes vocabulary, verbal reasoning, and literacy knowledge.

Scarborough "Rope" model

These components of decoding (D) and oral language comprehension (C) (and ultimately skilled reading) are clearly identified in the “Reading Rope” model by H Scarborough (2001) (Figure 2). This graphic shows that skilled reading also depends on the integration of the decoding/word recognition skills for the development of automaticity (fluency), which is the hallmark of a skilled reader.

Figure 2   The Scarborough 'Rope' Model of Skilled Reading

Scarborough rope model

Scarborough, H.S. 2001. Connecting early language and literacy to later reading (dis)abilities. Evidence, theory, and practice. In S. Neuman & D. Dickinson (Eds.), Handbook for research in early literacy (pp. 97–110). New York, NY: Guilford Press.

Dyslexia and the reading models

Gough & Tunmer, among others, have identified ‘dyslexia’ as a disability in word recognition ability. Intervention for this reading difficulty must be targeted on the foundational skills required for good word recognition, including phonological awareness, phonics (ie. alphabetic principle, letter-sounds) and rapid recognition/decoding of familiar words.

Research has clearly identified poor phonological awareness as a risk factor for dyslexia.  Intensive phonological awareness instruction can be very helpful for many readers with dyslexia.

Many readers also struggle with the development of automaticity in reading (fluency).  This difficulty has been linked to poor ability in Rapid Automatized Naming, which is the ability to quickly name familiar objects on a page, such as objects or numbers but most significantly, letters.  Fluency instruction, such as repeated readings, speed drills can be helpful in improving fluency, however, this challenge is often more difficult to remediate than reading accuracy.

Difficulties in reading comprehension but not word recognition/decoding ability is much less common; this has been termed ‘reading-comprehension impairment’ (Hulme & Snowling, 2011) or 'specific reading comprehension disability' (Spencer et al., (2014).  However, Spencer et al. (2014), in a study of over 425,000 first, second and third-grade students, found that, consistent with the simple view of reading, nearly all cases of poor reading comprehension were associated with inadequate decoding, oral language or both.  They conclude that "the term 'specific reading comprehension disability' is a misnomer: Individuals with problems in reading comprehension that are not attributable to poor word recognition have comprehension problems that are general to language comprehension rather than specific to reading."

To conclude, the reading models are helpful in understanding the foundational skills affected by dyslexia and Structured Literacy instruction, which explicitly teaches these foundational skills, will help students with dyslexia become more accurate and fluent readers.

Developing automaticity - orthographic mapping

A skilled reader can automatically recognize most words using the ventral pathway in the brain, as described in Neurobiology of dyslexia.   They no longer need to use the slower, 'decoding' pathway in the brain, although the 'decoding' pathway is the key to developing automaticity using the faster pathway.

Orthographic mapping is the term used to describe the process we use to store printed words in our long-term memory for 'automatic' word recognition.

Prominent reading expert Dr. David Kilpatrick (2015) estimates that skilled readers can instantly recognize between 30,000 and 70,000 words.  This instant recognition means that a skilled reader does not need to devote mental energy to identifying words and can dedicate their full attention to comprehension.  This set of instantly recognizable words is referred to as an "orthographic lexicon".   Helping students add words to their orthographic lexicon is clearly important to reading success.  But what is the most effective way to do this?

Words are not stored as images in our visual memory

For a long time, instant word recognition was not clearly understood. It was widely believed that whole words are stored as images in our visual memory.  This mistaken belief led to the popularity of many "look-say" instructional methods and resources. Many of these, like flashcards, word games like bingo or go fish and early readers that rely on repetitive predictable text continue to be in widespread use in our classrooms.

We now understand that, while it is possible to memorize some whole words and store them in visual memory, this is not the most efficient and effective way to build a set of instantly recognizable words.  Look-say methods may appear to be working during early reading when the number of words required is relatively small, however, students who rely on visual memory to read will often hit a wall around grade three.  For a student with dyslexia, these methods are particularly ineffective.

So how do we recognize words instantly?

While the visual memory stores whole words as images, orthographic memory stores information about the correspondences between letters or groups of letters and speech sounds.  For many people, orthographic memory is incredibly efficient at instant word recognition and skilled readers are very good at adding new words to their orthographic memory.

Decoding words helps build orthographic memory and automaticity

Everyone adds new words to their orthographic memory when they decode new words by systematically applying knowledge of letter-sound correspondences and spelling conventions to identify the word.  It is estimated typically developing readers need to decode a new word 1 to 4 times before it is permanently stored in their orthographic memory.

Individuals with dyslexia often have weaker orthographic memory and need to decode a word many more times before it becomes instantly recognizable.

Relying on cues from context, syntax or the initial letter does not develop orthographic memory

Many students also struggle to learn the underlying skills required to decode words.  When students are not able to decode words quickly and easily, they often taught to rely on cues from context, syntax, or by looking at a few of the initial letters to guess the word.  The use of these strategies does not help students store new words in their orthographic memory or become skilled readers. Every time a student uses cues from context or syntax to identify an unfamiliar word, an opportunity to expand the set of words in their orthographic memory has been missed. Instead, students should develop strong decoding strategies to read words, which will in turn, develop a larger bank of words in orthographic memory that can be accessed more quickly.

Check out this video about orthographic mapping:

Orthographic mapping by Lyn Stone.

Farrell, L., et al. 2010. The Simple View of Reading. The Center for Development and Learning Blog. February 1, 2010. Retrieved from:

Hulme, C. & M.J. Snowling. 2011. Children’s reading comprehension difficulties: nature, causes, and treatments. Current Directions in Psychological Science. 20(3):139-142.

Kilpatrick, D. A. 2015. Essentials of Assessing, Preventing, and Overcoming Reading Difficulties. Wiley & Sons Inc.

Scarborough, H.S. 2001. A discussion of evidence, theory, and practice connecting early language and literacy to later reading disabilities. In Newman, S.B. & D.K. Dickinson (Eds.), Handbook of early literacy research. P. 98. Guilford Press, New York, NY.

Spencer, M., J.M. Quinn, R.K. Wagner. 2014. Specific reading comprehension disability: major problem, myth, or misnomer? Learning Disabilities Research & Practice. 29(1):3-9.

Wren, S. 2001. The Cognitive Foundations of Learning to Read: A Framework. Southwest Educational Development Laboratory. Austin, TX.