Comparing the effects of processing instruction and production-based instruction on the regular verb form of English simple past tense: The role of explicit information

Over the last two decades, the importance of grammar instruction for second language (L2) development has occupied a major place in the pedagogy. This dissertation study investigated the effectiveness of processing instruction (PI) and production-based instruction (PBI) on the acquisition of English simple past tense regular verb morphology (-ed). In addition, the role of explicit grammatical information (EI) was examined. In total, 194 EFL university students at the preparatory school of a private university in Turkey were randomly selected to form four instructional groups: PI groups with EI (PI+EI) and without (PI-EI); PBI groups with EI (PBI+EI) and without EI (PBI-EI), and a control group. The performance of all five groups was measured three times throughout the study: a pretest one week before the study, an immediate posttest one day after the instructions, and a delayed posttest three weeks after the instructions. The tests included interpretation (aural and written) and production (oral and written) tasks. A series of 5 × 3 ANOVA with repeated measures were run for the analyses. Firstly, the results revealed that all four instructional groups improved their performance more than the control group from pretest to posttest 1 and posttest 2. Secondly, while PI+EI group outperformed PBI+EI group on the interpretation tasks, both groups performed equally well on the production tasks. Thirdly, however, PI-EI group did not perform better than PBI-EI group on the interpretation tasks; both performed equally well on the production tasks. Fourthly, no statistically significant difference was found for the comparison of PI+EI vs. PI-EI groups, and PBI+EI vs. PBI-EI groups, which thereby showed that EI did not play a significant role in either PI or PBI. This dissertation provides an array of theoretical, methodological, and pedagogical implications to L2 teachers in general and Turkish EFL teachers, in particular. For instance, the study showed that both PI and PBI were effective in helping Turkish EFL learners acquire the target form. But as for the greater effectiveness of the instructions among each other (PI+EI vs. PBI+EI and PI-EI vs. PBI-EI), especially on the interpretation tasks, PI-EI group receiving structured input activities alone did not perform better than PBI-EI group receiving structured output activities alone (PI-EI = PBI-EI). When EI was added as one component into instructional sequence for PI and PBI groups, this time PI+EI performed better than PBI+EI on the same interpretation tasks (PI+EI > PBI+EI), which thereby showed that VanPatten's input processing model needs one more component: Explicit Information (see figure 7). That is, structured input activities per se are not enough. This study partially confirmed VanPatten's processing instruction which helped learners produce as well as learners receiving production-based instruction on the production tasks. However, in contrast to what VanPatten found, processing instruction needed EI to be able to outperform PBI groups on the interpretation tasks. The study also offers some clear directions for future research to L2 researchers, such as the effect of L1 transfer on L2 interlanguage development and the involvement of computer-based tools such as "E-prime" as a methodological instrument to ensure the accuracy of the collected data.