Visual errors
In contrast to phonetic errors, these sound correct, but look wrong. Examples are ‘lite’ for ‘light’ and ‘grate’ for ‘great’. These errors suggest that the phonological system is being relied upon, because of difficulty with visual recall of familiar words (that is, a deficit in the lexical system described earlier).
Letter substitution errors
These errors result in the child writing ‘pig’ for ‘big’ or ‘log’ for ‘dog’. They may be a result of hearing, or auditory discrimination, problems. They may also be caused by visual perception difficulties. These underlying causes may be differentiated by special testing.
Insertion and omission errors
In an insertion error, an extra letter is added to a word, for example ‘beflore’ for ‘before’. In omission errors, letters are missing, such as ‘bicyle’ for ‘bicycle’. These errors can be due to lexical or phonological problems. Some omissions, particularly those of soft, high-frequency sounds such as ‘th’, may be due to subtle hearing problems.
Sequential errors
Sequential confusion results in errors such as ‘brigde’ for ‘bridge’. These are related to problems of sequential organization (see Chapter 10).
'Irrational' errors
These are errors that do not fit into the patterns just described. They neither look right nor sound right. Examples of such errors are ‘ritt’ for ‘right’ and ‘lift’ for ‘laugh’. Careful analysis of some of these errors may show an attempt at phonetic spelling. Children who make such errors have problems in phonological processes and in visual memory (lexical processes). Not surprisingly, they often have evidence of wider language difficulties.
