Types of language learner errors

1.  Language transfer errors

2.  Developmental errors (internal syllabus)
learner looks for
    consistent clues (avoid exceptions)
    clearly marked meaning
    semantic basis for grammar

based on frequency, saliency, and importance for meaning, grammar develops in stages with all learners making similar errors
    e.g.  Stages for the negative
                1st no/not + verb
                2nd don't + verb
                3rd  aux + not

            Stages for general grammatical patterns
                1st -ing, -s plural, be copula
                2nd  aux be, the/a
                3rd   irregular past
                4th   regular past, 3rd person singular verb -s, possessive -s

                   overgeneralization based on pattern observed

3. Performance errors based on communication strategies (making do with what you've got)

4.  Teacher induced errors (external syllabus)
                   partial or introductory pattern taught