Other categories

An inescapable and notorious feature of the English spelling system is that almost all phonemes have more than one spelling (nearly 300 graphemes are used to represent the roughly 44 phonemes - see again Burton, 2011 for handy lists of the main correspondences and some of the rarer ones that nevertheless occur in common words), and so in many cases it is not possible to lay down rules for which grapheme is the correct spelling of a phoneme in a particular word.

Fourteen subordinate categories

With these categories we begin to move from objective classification to speculation about causes; correspondingly, these minor categories are not mutually exclusive, and when errors are being analysed every error should be logged under all of these headings that are relevant (though there may be none), as well as in one of the main categories.

• Real word: The error is a real word, but not the one intended (but some real words are rare, e.g. ewe, wile - if such errors occur they should be counted in this category, and also listed separately to check whether the writer is being influenced by 'tricky' words)
• Homophone: If pronounced by regular spelling-to-sound rules (grapheme-phoneme correspondences), the error word would sound the same as the intended word. The error may be a real word, e.g. pair for pear, or a nonword, e.g. thort for thought (as a nonword which would sound the same as a real word, thort is an example of what psycholinguists call a 'pseudohomophone'.)
• Non-homophone: The attempted word has the correct number of graphemes to represent the number of phonemes in the target word (this restriction is necessary to avoid counting almost all errors as non-homophones), but if pronounced by regular grapheme-phoneme correspondences would not sound the same as the intended word. Again, errors may be real words, e.g. down for dawn, or nonwords, e.g. bak for bake (this would also be a letter-name error)
• Omission of 'silent' letter(s): Dropping a redundant letter, e.g. night for knight, or frend for friend (both of these are also homophone errors, but only the first is a real word error), or not representing a syllable which is often elided in speech, e.g. libry for library or necessry for necessary (N.B. Omission of a 'silent' letter is not to be confused with wrong deletion of 'magic <e>' below, since in stem words the <e> is not redundant.)
• Non-deletion of 'magic <e>': Retaining stem-final <e> when it should be dropped before a suffix beginning with a vowel letter, e.g. moveing for moving (but ageing for aging now seems regular)
• Wrong deletion of stem-final <e>: Dropping stem-final <e> before a suffix beginning with a vowel letter when it should be retained, e.g. managable for manageable, or servicable for serviceable (more on this and the previous category later)
• Non-replacement of final <y>: Not changing stem-final <y> to <i> before a suffix (other than <-ing>) beginning with a vowel letter (more on this later)
• Non-doubling: Not writing a consonant letter double when it should be, e.g. accomodation for accommodation, or occuring for occurring (more on this later too)
• Wrong doubling: Writing a consonant letter double when it should be single, e.g. off for of, or inn for in (both of which would also be real word errors, but only the latter would be a homophone error)
• Pronunciation effect: The error seems to arise from a non-standard pronunciation, e.g. fought for thought (this would also be a grapheme substitution in the main categories, and a real word error but not a homophone)
• Letter-name error: A letter is used to represent its name in the alphabet rather than its phonic sound, e.g. cr for car, or fl for fell
• Wrong spelling of the schwa vowel /ə/: This is the most frequent phoneme in spoken English, but it has over 30 different spellings (the most frequent is <a>, which accounts for only 35% of its occurrences), so misspellings are frequent. Examples would include docter for doctor, accommadation for accommodation, possable for possible, probible for probable
• Letter confusions: The subset of substitution errors where the letter written is similar in form to the target letter or its mirror-image or rotation, e.g. plag for play, beb for bed, tid for tip
• '<i> before/after <e>': The rule alluded to here is ridiculously unreliable (see more on subordinate categories section), but it may be instructive to collect transposition errors of this sort just to prove the point (for two much more reliable rules for spelling vowel phonemes also see two more reliable rules section).