Orthographic depth


The 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. In other words, shallow 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, Finnish, Turkish and Italian.
In contrast, in deep 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 and the letters that represent them. They may reflect etymology or be morphophonemic.
Written Korean represents an unusual hybrid; each phoneme in the language is represented by a letter but the letters are packaged into "square" units of two to 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".
Italian offers clear examples of differential directionality in depth. Even in a very shallow orthographic system, spelling-to-pronunciation and pronunciation-to-spelling may not be equally clear. There are two major imperfect matches of vowels to letters: in stressed syllables, e can represent either open or closed , and o stands for either open or closed . According to the orthographic principles used for the language, "sect", for example, with open can only be spelled setta, and "summit" with closed can only be vetta — if a listener can hear it, they can spell it. But since the letter e is assigned to represent both and , there is no principled way to know whether to pronounce the written words setta and vetta with or — the spelling does not present the information needed for accurate pronunciation. A second lacuna in Italian's shallow orthography is that although stress position in words is only very partially predictable, it is normally not indicated in writing. For purposes of spelling, it makes no difference which syllable is stressed in the place names Arsoli and Carsoli, but the spellings offer no clue that they are ARsoli and CarSOli.

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. 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. 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.
The phonetic writing systems of Japanese are another example of shallow orthography, but Japanese also uses logographs, which are significantly more complicated. Additionally, Latinization known as rōmaji is increasingly common but not used traditionally. However, in contrast to alphabetic orthographies, the Japanese hiragana and katakana orthographies are based on the open syllables of speech 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 kana is divided into syllables/morae with a simple V or C+V structure, rather than by individual vowels and consonants; fewer 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. 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 to those at the phonemic level, i.e., how difficult it is to convert graphemic strings 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, i.e., how to align a phonemic transcription to its spelling counterpart.
Xavier Marjou uses an artificial neural network to rank 15 orthographies according to their level of transparency. Among the tested orthographies, French orthography is the most opaque regarding writing and English is the most opaque regarding reading.