Written by Kathleen Hipfner-Boucher & Dr. Becky Chen
The average skilled adult reader has a “database” of between 30,000 and 70,000 words that are read instantly and effortlessly (Mather & Jaffe, 2021). That database is called an orthographic lexicon or a sight word vocabulary. An orthographic lexicon is essentially a mental dictionary of letter sequences that represent whole words or frequently recurring word parts (e.g., -tion) that are stored in memory for rapid retrieval when reading or writing. A complete “dictionary entry” includes information about the three forms of the word: its phonological form (its pronunciation); its orthographic form (its spelling); and its semantic form (its meaning(s) (Perfetti, 2007) (see figure 1.). The speed and ease with which words are retrieved from the orthographic lexicon depends on the degree to which these three forms are linked – or “bound” - to one another in memory. Unlike the names of the provincial and territorial capitals, or the months of the year in French, most words stored in the orthographic lexicon were committed to memory without conscious effort or explicit instruction in school.
A theory explaining how skilled readers build an orthographic lexicon is the orthographic mapping theory (Ehri, 2014). Orthographic mapping is the cognitive process by which children learn to read words by sight and to spell words from memory. Through orthographic mapping, letter-sound connections are formed that bond the pronunciations, spellings, and meanings of individual words in the sight word vocabulary. It is important to note that the definition of “sight word” as it relates to orthographic mapping differs from the more common definition. A sight word is commonly defined as an irregularly spelled, high-frequency word (the, she) that cannot be sounded out on a letter-by-letter basis. A sight word as it relates to orthographic mapping is a word that has been learned to the point that it is recognized instantly “on sight”.
The Building Blocks that Support Orthographic Mapping
To better understand what orthographic mapping is, let’s review a few concepts that underpin it, beginning with phonology and phonological awareness. Phonology refers to the sound system of a language. The phonological form of a word is, therefore, the way it is pronounced when spoken aloud. Spoken words are made up of phonemes, the smallest units of sound. There are 44 phonemes in English, each of which is represented by one or more letters or graphemes (for example, the phoneme /m/ is represented by the letter m, the phoneme /ʃ/ by the digraph sh as in shoe). Phonological awareness is an umbrella term that refers to the ability to isolate and play with the sounds of a language at the syllable, onset-rime and phoneme levels (Schuele & Boudreau, 2008). Children demonstrate phonological awareness when, for example, they can clap out the syllables in a word, produce rhyming words, or name words beginning with the same sound.
Phonemic awareness is the phonological awareness skill that is most important for learning to read an alphabetic language. That is because, in an alphabetic writing system, printed words are essentially sequences of characters that represent sequences of phonemes. Learning to first recognize letters and then letter patterns (e.g., -ight, -ough) and to pair them with their corresponding phonemes – referred to as grapheme-phoneme correspondence (GPC) – is essential if children are to become successful readers and writers. The phonemic awareness skills that are most important to master are phoneme blending (/k//a//t/--> cat) and phoneme segmentation (cat -->/k//a//t/). Knowledge of GPCs and proficiency in blending and segmenting are the intersecting skills that enable orthographic mapping (Ehri, 2014). Children who have difficulty reading words quickly and accurately tend to display weaknesses in all three, compromising their ability to map letter sequences onto known phonological word forms and to develop the sight word vocabulary on which fluent reading depends.
Whereas phonology relates to sound, orthography relates to the ways those sounds are represented by printed symbols. The word orthography comes from the Greek words orthos, meaning “right or true”, and graphein, meaning “to write”. In English, orthographic symbols include upper- and lower-case letters, numbers, and punctuation marks. Orthographic knowledge is the knowledge stored in memory of word spellings, commonly recurring spelling patterns, and the rules that govern what speech “looks like” in print in a given language (that u always follows q in English, for example, or that the vowels e and o may be doubled, but not a, i, and u) (Apel, 2011).
Different levels of orthographic knowledge are needed to become skilled readers and skilled writers (Mather & Jaffe, 2021). Skilled word reading involves automatic recognition of printed letters or letter sequences and blending of the individual phonemes they represent to retrieve a word’s spoken form. Skilled spelling, on the other hand, requires the segmentation of a word into its constituent phonemes and recall of the letter(s) associated with them to retrieve the words written form. Recall is more cognitively challenging than recognition and requires a more firmly established memory trace of the sequence of letters that make up a word. That is why, even as adults, we may have no trouble reading the words medieval or kaleidoscope but may need to pause and think before writing them. Children whose ability to process orthographic information is weak are less able to establish reliable connections between a word’s orthographic and phonological forms. As a result, they may have difficulty both recognizing words they read and recalling the order in which letters are sequenced in words.
What is orthographic mapping?
Orthographic mapping is the cognitive process by which readers associate phonemes with their corresponding graphemes so words can be stored for immediate “on-sight” retrieval (Ehri, 2014). Orthographic mapping allows the letters we see on the page to be mapped onto the sounds we hear in words so they may be stored, together with word meaning, in the orthographic lexicon. The process of orthographic mapping starts with knowledge of word pronunciation and meaning acquired through listening and speaking and connects it to new knowledge, the word’s spelling. How does this happen? When children begin to read, they rely on decoding to translate unknown printed words into spoken words (Share, 2004). Applying GPC rules, they sound out the letters in sequence, then blend the sounds to identify the word as a whole in a process that is slow and effortful. After repeated successful attempts to read the same word, the word’s orthographic form becomes bound to its phonologic and semantic form in long-term memory. The word then becomes a “sight word”, a word in the reader’s orthographic lexicon that is learned to the point that it is instantly recognized, without recourse to decoding and without conscious effort (Mather & Jaffe, 2021).
Orthographic mapping, then, allows children to develop fast and accurate, or fluent, word reading. Fluent word reading, in turn, allows the reader to direct mental resources to the primary purpose of reading: to construct meaning from text (Cunningham et al., 2010). Similarly, it allows children to spell words quickly and accurately from memory so that mental resources can be directed to more cognitively demanding tasks, such as idea generation, planning, and revising during the writing process. Importantly, as reading and spelling become less effortful, children can shift their focus from word form to word meaning. In this way, orthographic mapping supports the learning of vocabulary from print, as well as learning to read words by sight and spell words from memory.
The orthographic lexicon, or sight word vocabulary, is theorized to develop over time (Ehri, 2012). With the emergence of letter name and letter sound knowledge, children begin to use graphemes to represent the most salient sounds in words, most often the first or last sound. Over time, more complete knowledge of phonemes and the graphemes that typically represent them enables decoding and allows children to begin to build an orthographic lexicon in which phonology, orthography, and meaning are bound. Word reading fluency emerges. As more and more words are added to the orthographic lexicon, children come to rely on knowledge of larger orthographic “chunks”, in addition to GPCs, to support decoding and spelling of new words. These chunks include syllables, affixes, and inflections (such as markers of verb tense like -ed, or -ing as in walked and walking), and whole words read as single units.
Of course, it is not possible to explicitly teach children the orthographic form of every word they encounter in print. So how do they develop an orthographic lexicon numbering in the tens of thousands of words over time? Research tells us that it is the process of decoding words itself that enables children to independently learn the orthographic forms of new words. That is because decoding proceeds on a letter-by-letter basis, drawing attention to the specific letters and sequence of letters in words. Attention to letters and letter sequencing is key to orthographic mapping, as is knowledge of GPCs. As children successfully sound out a new word, connecting letters to sounds, they essentially “teach themselves” the letter sequence (or orthographic form) that represents the spoken form of the word stored in long-term memory along with the word’s meaning. At this point, the word can be read automatically and effortlessly (Share, 2004).
Keep in mind that many English words are irregular, meaning that they cannot be sounded out completely using knowledge of GPCs. However, even irregular words like friend have at least some regularity – all letters but the i are pronounced as expected – allowing for “partial decoding” (Share, 1995). When self-teaching an irregular word, partial decoding guides the reader toward the correct spoken word from the shortlist of spoken word candidates that make sense given the word’s context (for example, choosing friend over find in the context of the sentence: Sally was Alice’s best…). The self-teaching of new orthographic forms, be they regularly or irregularly spelled, largely takes place in the context of independent reading. Research tells us that as few as one to four exposures to novel words are enough to support the learning of new orthographic forms. In typically developing children, self-teaching occurs once children have gained experience and proficiency with the mechanics of reading.
Supporting the skills that support orthographic mapping
Orthographic mapping is the cognitive process by which children learn to read words by sight, spell words from memory, and learn new word meanings from print. Orthographic mapping is not a teachable skill and there is no such thing as an orthographic mapping activity. Instead, the skills that support orthographic mapping can and must be explicitly and systematically taught, beginning in preschool and kindergarten, if children are to become successful readers and writers. The skills that support orthographic mapping directly are proficiency in blending and segmenting and knowledge of grapheme-phoneme correspondences; instruction should begin there and eventually be coupled with extensive practice in reading decodable books. Integrating reading and spelling instruction is important; research indicates that providing children with a word’s spelling facilitates learning of its pronunciation and meaning (Miles & Ehri, 2019). Evidence-based resources for teaching the basic skills that enable orthographic mapping are available through the Florida Centre for Reading Research website (https://fcrr.org/). The website provides resources for educators and parents.
Apel, K. (2011). What is orthographic knowledge? Language, Speech, and Hearing Services in Schools, 42, 592-603.
Cunningham, A. E., Nathan, R. G., Schmidt Raher, K. (2010). Orthographic processing in models of word recognition. In M. L. Kamil, P. D. Pearson, E. Birr Moje, P. P. Afflerbach (Eds.). Handbook of reading research: Volume IV (pp. 259-285). New York: Routledge.
Ehri, L. C. (2014). Orthographic mapping in the acquisition of sight word reading, spelling memory, and vocabulary learning. Scientific Studies of Reading, 18, 5-21. DOI: 10.1080/10888438.2013.819356
Mather, N. & Jaffe, L. (2021). Orthographic knowledge is essential for reading and spelling. Reading League Journal, September/October, 15-25.
Miles, K. P. & Ehri, L. C. (2019). Orthographic mapping facilitates sight word memory and vocabulary learning. In D. Kilpatrick, R. M. Joshi, & R. K. Wagner (Eds.). Reading development and difficulties: Bridging the gap between research and practice (pp. 63-82). Cham, Switzerland: Springer.
Perfetti, C. (2007). Reading ability: Lexical quality to comprehension. Scientific Studies of Reading, 11, 357-383. DOI: 10.1080/10888430701530730
Schuele, C. M. & Boudreau, D. (2008). Phonological awareness intervention: Beyond the basics. Language, Speech, and Hearing Services in Schools, 39, 3-20.
Share, D. L. (2004). Orthographic learning at a glance: On the time course and developmental onset of self-teaching. Journal of Experimental Child Psychology, 87, 267-298.
Share, D. L. (1995). Phonological recoding and self-teaching: Sine qua non of reading acquisition. Cognition, 55, 151-218.
About the Authors:
Kathleen Hipfner-Boucher is a Senior Research Officer in the Multilingualism and Literacy Lab at the Ontario Institute in Studies in Education (University of Toronto). Her research focuses on the oral language skills that support reading comprehension among monolingual and multilingual children. She is particularly interested in looking at the ways that skills acquired in one language enable reading in a child’s other language(s).
Becky Xi Chen is a professor in the Department of Applied Psychology and Human Development at the Ontario Institute for Studies in Education. Her research examines language and literacy development of bilingual and multilingual children. She also specializes in dyslexia and reading comprehension difficulties among bilingual children.