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  • Writer's pictureStephen Parker

The "Sine Qua Non" of Reading Acquisition

Updated: Sep 26, 2021

With over 50 articles in refereed journals, David Share has been one of the most influential reading research scientists in the past 35 years. His research eventually led him to identify the skill he considered indispensable to skilled reading – so indispensable he called it the sine qua non of successful reading acquisition. Sine qua non is Latin for “that which is absolutely necessary.” Here’s an example of the phrase used outside the realm of reading instruction: Talent in math and physics is the sine qua non for a successful career in rocket science.

In this blog, I wish to explore Share's sine qua non of reading acquisition and its implications for phonemic awareness training and for initial reading instruction. In so doing we’ll see how Share’s research leads inexorably to Synthetic Phonics (not Whole Language or Balanced Literacy, not Analytic Phonics or SWI) as the only sensible method for teaching a child to read. [Most of the following quotes are from this particular article.]

Astonishingly, a skilled reader on the university level recognizes 50,000 or more words. These are words that no longer need to be identified by painstakingly sounding them out. They are simply recognized when encountered in print; their sound and meaning are immediately available. These are the words which have become “sight words” for the individual skilled reader.

How can such an impressive feat be accomplished? Share eliminates two possible answers: direct instruction, and contextual guessing. By “direct instruction,” Share means the teaching of new words in the classroom where the teacher supplies the identity of an unfamiliar word and the student, through considerable effort and drill, consciously transforms the word into a sight word by “direct rote association.”

As Share points out, such a method of teaching reading is unlikely to offer a “feasible word-acquisition strategy” when the typical 5th grader is already faced with reading 5,000 new words per year in natural printed text. [Do the math yourself. How many sight words must a student acquire, on average, per year in order to have a sight word inventory of 50,000 by college? If you wish to object that Chinese (or Japanese) students do learn to read their logographic writing system by rote memorization, see my blog here.]

By “contextual guessing” Share means “the use of syntactic, semantic, and pragmatic information in the surrounding text to predict unfamiliar words.” If we include the use of pictures to assist with the guessing, what Share is discussing here is “three-cueing.” Why can’t contextual guessing be effective if the goal is to produce a skilled reader? Share’s answer is straightforward. Study after study reveals that if the word being guessed is a content word (for example: MOROSE, GRACEFULLY, CONGEAL, ISOTOPE) rather than a function word (HIM, OF, BUT, HAVE), the predictability rate is only 10-20%. (Content words carry the bulk of a sentence’s meaning in natural text.) Share concludes: “It seems that contextual guessing is least helpful where it is needed most.”

Worse, from the point of view of building the necessary sight word inventory of a future skilled reader, it’s not enough to guess a word with a plausible meaning (HORSE when the actual word is PONY), or even to guess the exact word. Transforming the word into a sight word involves deliberate analysis, matching the word’s individual letters (graphemes) to the word's individual sounds (phonemes). Without such analysis, the same word, reappearing next week, will have to be guessed all over again.

So, if a child needs to acquire 50,000 sight words to succeed in college, and neither direct instruction nor contextual guessing has a chance in hell of getting the child there, how can such an achievement occur? Share says there is only one possible answer: the child must be provided the ability to self-teach. According to Share’s Self-Teaching Hypothesis,

"Word-specific orthographic representations are acquired primarily as a result of the self-teaching opportunities provided by the phonological recoding of novel letter strings." (See here, p95)

This academese may need some translation: Specific words and their exact spellings become sight words as a result of the self-teaching opportunity provided by the skill of decoding. Share continues:

“According to the self-teaching hypothesis, each successful decoding encounter with an unfamiliar word provides an opportunity to acquire the word-specific orthographic [spelling] information that is the foundation of skilled word recognition. A relatively small number of (successful) exposures appear to be sufficient for acquiring orthographic representations [sight words], both for adult skilled readers and young children.” (p155)

Three items here might need some clarification. First, by “decoding,” Share means the full “sounding out” of a word. This is accomplished by matching the correct sound (phoneme) to each of a word’s letters (graphemes) and then blending those sounds, left to right, into a complete pronunciation. This needs to be said because in Balanced Literacy circles, every strategy from “try again,” to “make attempts that make sense,” to “skip and return” is considered “decoding.” Such nonsense strips the word “decoding” of all meaning. (See, for example, Chapter 3 in Jennifer Serravallo’s The Reading Strategies Book. For my review of her book, see here.)

Second, decoding is used only in identifying words, not in recognizing them. Share uses the phrase “word recognition” to refer to sight words for which decoding is no longer necessary. “Decoding” is the self-teaching mechanism used for word identification. “Although it may not be crucial in skilled word recognition, decoding may be the principal means by which the learner attains word recognition proficiency.”

Third, for Share, the self-teaching enabled by competent decoding applies even to irregular words because “most irregular words, when encountered in natural text, have sufficient letter-sound regularity (primarily consonantal) to permit selection of the correct target among a set of candidate pronunciations.” (p166)

And so we’ve arrived at Share’s sine qua non of reading acquisition. It’s simply the ability to self teach by decoding new words while reading natural text. Such decoding automatically adds those words to an ever-growing personal inventory of sight words. As Share expresses it,

“The ability to use knowledge of spelling-sound relationships to identify unfamiliar words is the sine qua non of reading acquisition." (p156) "There can be no case of competent reading in the absence of functional decoding.” (p173)

If self teaching by means of decoding is the sine qua non of reading acquisition, the next logical question is this: Which skills enable competent decoding? Whatever these skills are, they’re the key because they make possible the sine qua non of reading acquisition.

Share provides two answers to this question. The first is that the child become aware of phonemes.

“In order to exploit the self teaching advantages of an alphabetic orthography [spelling system], the learner must have a working knowledge of the phonemes mapped [represented] by the orthography.” (p190)

[Note: There are 44 phonemes in spoken English. If you’re interested in knowing exactly what these fundamental sounds are, see here.]

Share elaborates: “Self-teaching requires an appreciation that spoken words are composed of a limited number of phonemes which can be combined to generate a virtually infinite number of possible words.” (p191) Acknowledging that a variety of units (morphemes, syllables, and phonemes) are represented by our spelling system, Share states the obvious: “English is first and foremost a phonemic script.” [my emphasis]

The second skill needed for competent decoding is this:

“Although an awareness of phonemes is necessary for successful reading acquisition, it is not sufficient. Hand in hand with this phonemic understanding, the learner must possess a thorough knowledge of the written symbols that transcribe these units, that is, a knowledge of letter-sound correspondences.” (p191)

At this point you may be thinking: “Hold on, does Share mean to say that it’s only:

  1. phonemic awareness, and

  2. knowledge of letter-sound correspondences

that are necessary for a child to decode, and therefore self-teach?”

Here’s Share making that exact point even more explicit:

“Since studies tend to show that neither letter-sound knowledge alone nor phonemic awareness alone are sufficient, we can conclude that phonemic awareness and letter-sound knowledge are causal co-requisites for successful reading acquisition.” (p192)
“The consistency and magnitude of the effect sizes in predictive and experimental studies indicates that knowledge of the alphabetic code and the phonemes represented by that code constitute critical co-requisites to successful early reading acquisition. Jointly, these two factors account for a majority of the variance in early reading achievement.” (p192)

“Phonemic awareness” is, as Share knows, a rather broad term, meaning different things to different people. It can mean training in phoneme segmentation, that is, listening to a spoken word and then separating it into its constituent phonemes. If those phonemes are then matched with the letters which represent them, the process is better known as spelling. Segmentation is the key skill in analytic phonics (analysis).

“Phonemic awareness” can also mean training in phoneme blending, that is, seeing a written word, assigning a phoneme to each of the word’s letters (or letter pairs), and then combining those sounds into a full pronunciation. This process is also known as decoding – the same decoding referred to earlier as the sine qua non of reading acquisition. Blending is the key skill in synthetic phonics (synthesis).

So what type of "phonemic awareness" is Share talking about?

When Share calls “phonemic awareness” a causal co-requisite for reading, he acknowledges that “the pattern of results appears to depend on precisely which phonemic awareness skills (synthesis versus analysis) are taught.” [192] Based on the research studies of others, as well as his own research, Share concludes:

“When phonemic awareness training includes blending (in addition, of course, to letter-sound training), trained groups consistently outperform controls. When phonemic analysis (segmentation) alone is trained (even in conjunction with letter-sound knowledge), findings are consistently negative. The research clearly points to synthesis [blending[ as the critical factor as far as reading is concerned.” (p193) [emphasis mine]
“In summary, there is strong evidence for a causal role of phoneme synthesis (blending) as a twin co-requisite (alongside letter-sound knowledge) for successful reading acquisition. This conclusion is supported by both laboratory and field studies. Additional support comes from research comparing initial programs of reading instruction. Phonics programs which explicitly teach blending produce superior results compared to "analytic" programs which generally do not include a blending component.” (p194) [emphasis mine]

Share acknowledges, however, that analysis (segmentation) is likely necessary for skilled spelling. (p194)

So, for Share, letter-sound knowledge (which is phonics proper), and phoneme awareness (in the form of phoneme blending) are the twin causal co-requisites for decoding and for skilled reading acquisition. Does that mean phonemic awareness training needs to occur before formal phonics training begins? Share says no. Pointing to the fact that adult illiterates lack awareness of phonemes, Share states the obvious:

“These findings suggest that phonemic awareness does not develop spontaneously in the normal course of cognitive and linguistic development, but only in the specific context of learning to read an alphabetic script.” (p195)
“Most children develop an awareness of phonemes as they learn to read.”
“Present evidence indicates that phonemic awareness is best classified not as a basic phonological [sound] processing ability, but as a reading skill… Thus lack of phonemic awareness does not necessarily imply a basic phonological deficiency.” (p196)
“Lack of phonemic awareness not only can but does cause reading failure.” (p196)

Let’s re-cap. It’s impossible to become a skilled reader (in the sense of recognizing 50,000 sight words by age 20) without the ability to self-teach. The ability to self-teach while reading natural text implies skillful through-the-word decoding. But decoding, itself, has two causal co-requisites: letter-sound knowledge (phonics) and a specific type of phonemic awareness, namely, phoneme blending. Further, this type of phonemic awareness training is best taught as a component of reading instruction, that is, as a component of phonics itself. There’s only one type of phonics that fits this description, and it does so elegantly and precisely: synthetic phonics. (See here for a more complete description of what synthetic phonics is and does.)


The bulk of David Share’s research and writing was done between 1988 and 2008. It had an unmistakable influence on England’s national inquiry into the teaching of reading. That study, called the Rose Report, called specifically for Synthetic Phonics in the teaching of early reading. Here’s an excerpt:

“Having considered a wide range of evidence, the review has concluded that the case for systematic phonic work is overwhelming and much strengthened by a synthetic approach, the key features of which are to teach beginner readers:
1) grapheme/phoneme (letter/sound ) correspondences (the alphabetic principle) in a clearly defined, incremental sequence, 2) to apply the highly important skill of blending (synthesizing) phonemes in order, all through a word to read it, 3) to apply the skills of segmenting words into their constituent phonemes to spell, and 4) that blending and segmenting are reversible processes.
All of these elements featured consistently in the best work seen…The sum of these elements represent ‘high quality phonic work’.” (See here, para 45-52)

Share has also had significant influence on Linnea Ehri, another giant in the area of reading research. It was she who coined the term orthographic mapping to describe the process whereby readers, using decoding, automatically acquire sight words, and begin to self-teach. Here’s Ehri acknowledging her debt to Share:

“To form connections and retain [sight] words in memory, readers need some requisite abilities. They must possess phonemic awareness, particularly blending and segmentation. They must know the major letter-sound correspondences of the writing system. Then they need to be able to read unfamiliar words on their own by applying a decoding strategy.” Doing so “activates orthographic mapping to retain the words’ spellings, pronunciations, and meanings in memory. David Share referred to this process as a self-teaching mechanism.” (See here, p7)
"The ability to decode words never read before, by blending letters into a pronunciation, enables readers to form fully connected sight words in memory." (See here, p21)

Stanislas Dehaene is one of today’s leading neuroscientists. His best selling book, Reading in the Brain, details how the brain is literally rewired in the act of learning how to read. The following quotes clearly exhibit Share’s direct influence on Dehaene:

“The mastery of reading lies, above all, in our ability to decode new words. ‘Self-teaching’ is an essential ingredient on the road to independent reading. Once they master spelling-to-sound correspondences, children can, on their own, decipher the pronunciation of a novel string and associate it with a familiar meaning. With ‘self-teaching,’ the neuronal links from letter strings to sound and to meaning can be progressively automatized without any further formal instruction.” (p226)
“This process [of decoding] whereby written words are converted into strings of phonemes, must be taught explicitly.” (p219)
“The punch line is quite simple: we know the conversion of letters into sounds is the key stage in reading acquisition. All teaching efforts should be initially focused on a single goal: the grasp of the alphabetic principle whereby each letter [or letter pair] represents a phoneme.” (p228)


Researchers have known, for at least a quarter century, how to teach reading in a manner that would allow the vast majority of our children to become independent, self-teaching readers within a year or two. What’s needed, sketched out above, is precisely what's provided by the teaching method called Synthetic Phonics.

This is a case where basic common sense happens to coincide with science: to teach a child, efficiently, how to read an alphabetic script, teach the child what the letters are, which sound(s) those letters represent, and how to blend those sounds into full words. This will allow the child to quickly make explicit the letter-sound connections that are at the heart of skilled decoding, self-teaching, and Orthographic Mapping.

Stephen Parker

July 2020

(Twitter @ParkerPhonics)


Where can you find a resource that will guide you in teaching a child (or adult) to read, in a manner that respects Share's sine qua non? On this site are stand-alone Synthetic Phonics books that will do just that - and they're 100% FREE. Simply pick out the one that's right for you and download it. I invite you to read my other blogs on the Science of Reading as well.



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