The language production system occasionally slips up and causes a speech error. The categories of speech errors include:

Morpheme errors

These occur when morphemes are accidentally interchanged. They can take the form of inflectional morpheme or derivational morpheme.

For example; a cup of tea – a tea of cup (inflectional) singing in the garden – sing in the gardening (derivational). Inflectional morphemes occur when word placement change happens with morphemes not changing (Goldstein, et al., 2007), while derivational morpheme is when an error occur due to the addition or substitution of a morpheme, with the main words remaining.

Phonemic errors

These occur when sounds are unexpectedly interchanged between words. They are the commonest category of speech errors and mostly happens between words that are separate. They mostly involve anticipations where the speaker says a sound that is supposed to feature in the later portions of the sentence. For example, sea shore – she shore, she said – she shed (MacNeilage, 2012). Phonemic errors can also take the form of perseverance, where the portion that interferes comes before the error. These errors show that the speech was already adequately planned before the actual articulation. The cause could be that the mind perceives that all the words of a sentence are a single entity and this causes mixing at the planning stage.

Syllable errors

The initial portions replace first parts, and final segments do the same. Research shows that speech errors do occur at a distance of within seven syllables between the start and the target (MacNeilage, 2012). Considering a case where there are two words with similar syllable content, an error will occur due to the exchange of these syllables. This means that the first syllable in the first word replaces the first syllable of the second word. For example, care for man – can for mare. Syllable deletion can also occur e.g. unintelligible – intelligible.