Orthographic depth

Orthographic depth of an alphabetic orthography indicates the degree to which a written language deviates from simple one-to-one letter-phoneme correspondence. It depends on how easy it is to predict the pronunciation of a word based on its spelling: shallow orthographies are easy to pronounce based on the written word, and deep orthographies are difficult to pronounce based on how they are written.

In shallow orthographies, the spelling-sound correspondence is direct: from the rules of pronunciation, one is able to pronounce the word correctly.^[1] In other words, shallow (transparent) orthographies, also called phonemic orthographies, have a one-to-one relationship between its graphemes and phonemes, and the spelling of words is very consistent. Such examples include Spanish, Italian, Finnish, and Turkish.

In contrast, in deep (opaque) orthographies, the relationship is less direct, and the reader must learn the arbitrary or unusual pronunciations of irregular words. In other words, deep orthographies are writing systems that do not have a one-to-one correspondence between sounds (phonemes) and the letters (graphemes) that represent them. They may be irregular (English), reflect etymology (Hungarian, Faroese or French) or be morphophonemic (Korean).

Written Korean represents an interesting hybrid; each phoneme in the language is represented by a letter but the letters are packaged into "square" units of three or four phonemes, each square representing a syllable. Korean is not completely shallow but has some exceptions in which the written word is not pronounced exactly as the individual letter-phoneme correspondences would otherwise require. English has many such instances: compare the pronunciation of the letter "c" in the words "magic" and "magician" or the pronunciation of the letter "i" in "pint" and "mint".

Orthographic depth hypothesis

According to the orthographic depth hypothesis, shallow orthographies are more easily able to support a word recognition process that involves the language phonology. In contrast, deep orthographies encourage a reader to process printed words by referring to their morphology via the printed word's visual-orthographic structure.^[2] For languages with relatively deep orthographies such as English, French, Arabic or Hebrew, new readers have much more difficulty learning to decode words. As a result, children learn to read more slowly.^[3] For languages with relatively shallow orthographies, such as Italian and Finnish, new readers have few problems learning to decode words. As a result, children learn to read relatively quickly.^[3]

The phonetic writing systems of Japanese (hiragana and katakana) are another example of shallow orthography, but Japanese also uses logographs (kanji), which is significantly more complicated. However, in contrast to alphabetic orthographies (English, French, Italian, Turkish, etc.), the Japanese hiragana and katakana orthographies are based on the open syllables of speech (consonant-vowel) or, more precisely, on the mora, with one written symbol for each of the syllables/moras in the language. While Japanese has only 3 graphemes for six phonemes like in the word katana (Japanese hiragana:かたな, Japanese katakana: カタナ IPA: /ka ta na/) Japanese kana is divided into syllables/morae with a simple V or C+V structure (with one -C mora that typically only appears at the ends of syllables), rather than by individual vowels and consonants; less graphemes are needed to write a word. Since Japanese phonology is relatively simple compared to many other languages, writing Japanese using syllables rather than alphabetic letters is a feasible option.

Bosch et al.^[4] consider orthographic depth to be the composition of at least two separate components. One of these relates to the complexity of the relations between the elements at the graphemic level (graphemes) to those at the phonemic level (phonemes), i.e., how difficult it is to convert graphemic strings (words) to phonemic strings. The second component is related to the diversity at the graphemic level, and to the complexity of determining the graphemic elements of a word (graphemic parsing), i.e., how to align a phonemic transcription to its spelling counterpart.

References

1. Besner, D., Smith, M. C. (1992). Basic processes in reading: Is the orthographic depth hypothesis sinking? In R. Frost & L. Katz (Eds.), Orthography phonology morphology and meaning Advances in psychology Vol 94 (pp. 45-66). North-Holland, Oxford, England. Retrieved from http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=1993-97079-003
2. Katz, L. & Frost, R. (1992). The reading process is different for different orthographies: The orthographic depth hypothesis. In Frost, R. & Katz, L., (Eds.). Orthography, Phonology, Morphology, and Meaning, pp. 67-84. Amsterdam: Elsevier North Holland Press.
3. Goswami, Usha (2005-09-06). "Chapter 28: Orthography, Phonology, and Reading Development: A Cross-Linguistic Perspective". in Malatesha, Joshi. Handbook of orthography and literacy. Lawrence Erlbaum Assoc Inc. pp. 463–464. ISBN 0-8058-4652-2.
4. Van den Bosch, A., Content, A., Daelemans, W., and De Gelder, B. (1994). Analysing orthographic depth of different languages using data-oriented algorithms. available at http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.48.9845&rep=rep1&type=pdf