A comparative investigation of lexical networks of Turkish learners of English as a foreign language: A corpus based study

The current study is composed of two main parts as descriptive and experimental. The aims are, first to determine lexical differences between texts written by Turkish EFL learners and native speakers of English, and then to make use of corpus-based language learning activities to help the learners overcome lexicon related problems. In the descriptive phase of the study, essays written by 49 Turkish EFL learners and 100 native speakers of English were compared. These essays were processed in Coh-metrix which is an online database. One of the indices in Coh-metrix, Latent Semantic Analysis (LSA), was used to compare lexical cohesion in learners? texts to the native ones. Statistical analyses revealed that learner essays were significantly different from native ones in referential, semantic, reading comprehensibility and syntactic aspects. Focus group interviews which were carried out with the same learner group brought to light that these differences mostly stemmed from lexicon related problems. This point was the main rationale behind the quasi-experimental phase of the study.In the quasi-experimental phase, 37 intermediate and upper-intermediate level Turkish EFL learners participated in the study. The experimental group was composed of 18 learners, and there were 19 learners in the control group. Before the treatment, both groups were given vocabulary recognition and essay writing tests. The experimental treatment included corpus-based concordancing activities. This treatment lasted for about 10 weeks, and at the end, both groups were given the same vocabulary recognition and writing test again. In order to test the delayed effects of the treatment, the same written test was given to both groups after about two weeks.Analysis results revealed that the experimental group obtained significantly better scores compared to the control group in terms of vocabulary recognition and production. However, concordancing activities did not have any significant effects on lexical cohesion in control group?s texts. As the last stage of the study, the participants were interviewed about the use of concordancing activities in language instruction. The results indicated that the majority of the participants improved positive attitudes towards these activities and found them beneficial.