Abstract:
This study investigated overgeneralisation of derivational rules by EFL secondary learners at ‟Mabathoana High School. The study used a triangulation of three instruments to collect data: online focus groups, online interviews, and documents (compositions) with a qualitative research design. Premised on Aronoff‟s (1976) word formation theory and EA procedures, the study examined and analysed a corpus of one hundred learners (30 grade 9, 30 form E, 40 form E students) and nine (9) English teachers. The findings revealed that students mostly overgeneralised the derivational prefixes un-, in-, and dis- which are reversative and negative prefixes. The suffixes that were mostly overgeneralised were -ness, -tion, -ment, -ful, -able -ify and -ise which are nominal, adjectival, and verbal forming suffixes. The study further discovered that the causes of these overgeneralisations are that EFL teachers and learners do not know derivational rules and restrictions of these rules. Another cause is that students lack a reading culture and therefore are not familiar with the English vocabulary, hence the overgeneralisations of the rules. The corpus also evidenced that these overgeneralisations have a detrimental effect on the students‟ language proficiency as such errors are regarded as very serious.
