effects of cooperative learning on vocabulary achievement of reflective/impulsive iranian efl learners

this study examined the effects of cooperative learning techniques (clt) on vocabulary achievement of reflective/impulsive iranian efl learners. from among 130 students at fajr institute in dehdasht, kohkiloyeh and boyer ahmad province, iran, 90 participants were selected based on their performance on the oxford placement test (opt). the participants were then divided into two experimental groups (comprising reflective learners and impulsive learners) and one control group labeled as conventional instruction (ci) group. the instrument used to divide the participants into reflective and impulsive groups was the eysenck’s (1990) impulsivity questionnaire. the experimental groups were taught with the student team achievement division (stad) technique, while the control group was taught through the traditional method for ten weeks. to measure the vocabulary knowledge of the learners in different groups at the beginning and at the end of the experiment, a pretest and a posttest, each consisting of 40 items on new english words based on their book were used. independent-samples and paired-samples t tests were used to determine whether there were significant inter- and intra-group differences. the statistical analysis of the results showed that the experimental groups (reflective and impulsive) performed better on vocabulary achievement posttest than the control group (ci), and also it was revealed that reflective learners performed better on vocabulary achievement than impulsive learners. in sum, cooperative learning enhanced learners’ vocabulary performance, especially the reflective ones.