The effects of input enhancement and explicit instruction on developing Iranian lower-intermediate EFL learners' explicit knowledge of passive voice

ERCT Criteria Breakdown

• Level 1 Criteria

  • C

    Class-level RCT

    • Randomisation was at the individual student level within one institute, not at the class or school level, and the intervention is not one-to-one tutoring.
    • "Then, these participants were randomly assigned into three groups: (1) explicit instruction (n = 16), input enhancement (n = 16) and control (n = 16)."
    • Relevant Quotes: 1) "To this end, 48 lower- intermediate EFL students participated in the present research and a pretest-posttest quasi experimental design with two experimental groups and a control group was adopted." (p. 1, Abstract) 2) "Then, these participants were randomly assigned into three groups: (1) explicit instruction (n = 16), input enhancement (n = 16) and control (n = 16)." (p. 8) 3) "Due to availability of the participants to the first reseacher, convenience sampling method, a type of non-probability sampling, was adopted for sample selection." (p. 8) 4) "It is worth noting that the first researcher herself was the instructor of all three groups." (p. 11) Detailed Analysis: The unit of randomisation was the individual student: 48 selected students were "randomly assigned into three groups" of 16. There is no mention of intact classes or schools being randomised; instead, individual learners drawn by convenience sampling from one private language institute were allocated to the three conditions. The three groups were then taught as separate groups, but the assignment itself was at the student level, and the same instructor (the first researcher) taught all three groups, which increases the risk of cross-condition contamination that class-level randomisation is meant to prevent. The intervention is classroom group instruction of grammar, not one-to-one tutoring or personal teaching, so the tutoring exception does not apply. Criterion C is not met because randomisation was conducted at the individual student level rather than at the class or school level, and no tutoring exception applies.
  • E

    Exam-based Assessment

    • Outcomes were measured with custom researcher-designed tests (UGJT and an adapted MKT), not widely recognised standardised exams.
    • "In the present research, Untimed grammaticality judgment test (UGJT) was designed based on the principles described in Ellis (2005)."
    • Relevant Quotes: 1) "In the present research, Untimed grammaticality judgment test (UGJT) was designed based on the principles described in Ellis (2005)." (p. 8) 2) "The test consisted of 10 grammatical ... and 10 ungrammatical sentences ... The test also contained five distracters. Overall the test included 25 items." (p. 8) 3) "The second measure, metalinguistic knowledge test (MKT), is an adaptation of the previous test developed by Alderson, Clapham and Steel (1997)." (p. 9) 4) "The Cronbach's alpha reliability of the test was 0.86 and the face and content validity of the test was established by two experienced English teachers." (p. 9) 5) "In order to choose homogeneous participants in terms of language proficiency, the researcher administered Oxford Quick Placement Test (2001) among 57 participants." (p. 8) Detailed Analysis: The outcome measures were a researcher-designed untimed grammaticality judgment test (UGJT) "designed based on the principles described in Ellis (2005)" and a metalinguistic knowledge test (MKT) adapted by the researchers from Alderson et al. (1997). Both are custom instruments constructed specifically for this study to target simple present and simple past passive voice; neither is a widely recognised, standardised exam. The only standardised test used (Oxford Quick Placement Test) served solely as a screening tool for participant selection, not as an outcome measure. The reliability and validity checks were done in-house by the researchers and two teachers, which does not turn the instruments into recognised standardised exams. Criterion E is not met because outcomes were measured with custom, researcher-made tests (UGJT and MKT) rather than a standard, widely recognised standardised exam.
  • T

    Term Duration

    • Outcomes were measured about five weeks after the intervention began, far less than one full academic term.
    • "At the next phase, participants of each group received instruction for four weeks, one session per week. One week after the treatment, the posttests were administered..."
    • Relevant Quotes: 1) "One week prior to the treatment, the Oxford Quick Placement test (2001) was administered to 57 EFL students..." (p. 10) 2) "At the next phase, participants of each group received instruction for four weeks, one session per week. One week after the treatment, the posttests were administered to check the participants knowledge gain of the selected structures." (p. 10) 3) "Then, two reading passages containing simple past and simple present were practiced during each one-hour session." (p. 11) Detailed Analysis: The intervention lasted four weeks (one one-hour session per week), and the posttests were administered one week after the treatment ended. The interval from intervention start to outcome measurement is therefore about five weeks, which is far shorter than one full academic term (approximately 3-4 months). No delayed follow-up test was administered; indeed the authors themselves recommend that "Future studies are recommended to investigate the durability or long-term effects" (p. 16), confirming that no longer-term tracking occurred. Criterion T is not met because the interval from intervention start to outcome measurement was only about five weeks, well short of one academic term.
  • D

    Documented Control Group

    • The control group's size, demographics, baseline scores and exact conditions are clearly documented, enabling proper comparison.
    • "The control group, (n = 16) also received the same passages in the same order. The control group received neither explicit instruction nor enhanced input treatment with respect to the passive voice."
    • Relevant Quotes: 1) "Then, these participants were randomly assigned into three groups: (1) explicit instruction (n = 16), input enhancement (n = 16) and control (n = 16). All participants were Iranian with Persian as their first language. Their age range was between 13 to 19 years." (p. 8) 2) "The control group, (n = 16) also received the same passages in the same order. The control group received neither explicit instruction nor enhanced input treatment with respect to the passive voice. They were merely involved in pre-reading, while-reading and post-reading activities." (p. 11) 3) "Results of a one-way ANOVA indicated that no significant differences were found among the groups on the UGJT at the p > 0.5 level, [F (2, 41) = 1.14, p = 0.32]. Therefore, the participants were comparable with respect to their knowledge of passive voice, as illustrated in Table 1." (p. 12) 4) "Therefore, the data of only 44 participants, including explicit instruction group (n = 15), input enhancement group (n = 15) and control group (n = 14) were considered for the final analyses." (p. 11) Detailed Analysis: The control group is described in reasonable detail: its size (n = 16 assigned, n = 14 analysed), its composition (Iranian lower-intermediate EFL learners aged 13-19, Persian L1, selected via the Oxford Quick Placement Test with scores 24-30), and exactly what it received (the same eight reading passages in the same order with pre-, while- and post-reading activities, but no explicit instruction or input enhancement). Baseline comparability was checked with one-way ANOVAs on both pretests (Tables 1 and 4), which showed no significant group differences. This documentation of who the control group was, their baseline performance, and the conditions they experienced satisfies the requirement. Criterion D is met because the control group's size, characteristics, baseline performance and treatment conditions are clearly documented.

• Level 2 Criteria

  • S

    School-level RCT

    • Individual students within a single site were randomised; there was no school-level randomisation.
    • "Then, these participants were randomly assigned into three groups: (1) explicit instruction (n = 16), input enhancement (n = 16) and control (n = 16)."
    • Relevant Quotes: 1) "Then, these participants were randomly assigned into three groups: (1) explicit instruction (n = 16), input enhancement (n = 16) and control (n = 16)." (p. 8) 2) "Due to availability of the participants to the first reseacher, convenience sampling method, a type of non-probability sampling, was adopted for sample selection." (p. 8) Detailed Analysis: The study took place with students drawn from a single site accessible to the first researcher (a private English language institute context in Iran), and randomisation was performed at the individual student level. No schools, institutes, centres or other institutional units were randomised; there is only one implementing site. Criterion S requires random assignment of whole schools or comparable institutional units to conditions, which clearly did not occur here. Criterion S is not met because randomisation occurred among individual students within a single site, not among schools or institutional units.
  • I

    Independent Conduct

    • The authors designed, taught, tested and analysed the study themselves with no independent third-party involvement.
    • "It is worth noting that the first researcher herself was the instructor of all three groups."
    • Relevant Quotes: 1) "It is worth noting that the first researcher herself was the instructor of all three groups." (p. 11) 2) "In the present research, Untimed grammaticality judgment test (UGJT) was designed based on the principles described in Ellis (2005)." (p. 8) 3) "This article was written based on the first author's master's thesis, which was completed in partial fulfillment for the master's degree. It was completed under the supervision of the second author." (p. 17) 4) "A second rater, an experienced English teacher, was asked to rate the test and no deviance was found between the two ratings..." (p. 9) Detailed Analysis: The same researchers designed the intervention, delivered all instruction (the first author personally taught all three groups), designed the outcome measures, collected the data and performed the analyses as part of the first author's master's thesis. There was no external evaluation team, independent data collectors, or third-party oversight; the only external involvement was a second rater for the MKT scoring, which does not constitute independent conduct of the study. This design creates exactly the implementation and measurement bias risks that criterion I is intended to exclude. Criterion I is not met because the intervention designers themselves delivered the instruction, collected the data and analysed the results with no independent oversight.
  • Y

    Year Duration

    • The study spanned only about five weeks from intervention start to posttest, far below 75% of an academic year.
    • "At the next phase, participants of each group received instruction for four weeks, one session per week. One week after the treatment, the posttests were administered..."
    • Relevant Quotes: 1) "At the next phase, participants of each group received instruction for four weeks, one session per week. One week after the treatment, the posttests were administered..." (p. 10) 2) "Future studies are recommended to investigate the durability or long-term effects of explicit/implicit instructional approaches on explicit knowledge of EFL learners." (p. 16) Detailed Analysis: Criterion Y requires outcomes to be measured at least 75% of an academic year (roughly 9-10 months) after the intervention begins. Here the whole study, from intervention start to posttest, spanned about five weeks, and the authors explicitly note that long-term effects were not investigated. Because the weaker Term Duration criterion (T) is already not met, this stronger Year Duration criterion cannot be met either. Criterion Y is not met because the tracking period was only about five weeks, nowhere near 75% of an academic year, and criterion T is not met.
  • B

    Balanced Control Group

    • All groups received equal time, identical passages and the same instructor, so inputs were balanced and only the tested instructional technique differed.
    • "The common core of the treatment for all three groups was eight passages containing target structures. All three groups were asked to read the same passages, two passages per session, and then answer the same questions following reading texts."
    • Relevant Quotes: 1) "The common core of the treatment for all three groups was eight passages containing target structures. All three groups were asked to read the same passages, two passages per session, and then answer the same questions following reading texts." (p. 10) 2) "Then, two reading passages containing simple past and simple present were practiced during each one-hour session." (p. 11) 3) "The second experimental group (n = 16), known as input enhancement group, received the same passages with the selected passive forms enhanced via combinations of two techniques (i.e., bolding and underlining)..." (p. 11) 4) "The control group, (n = 16) also received the same passages in the same order. The control group received neither explicit instruction nor enhanced input treatment with respect to the passive voice. They were merely involved in pre-reading, while-reading and post-reading activities." (p. 11) 5) "It is worth noting that the first researcher herself was the instructor of all three groups." (p. 11) Detailed Analysis: Following the decision tree: did the intervention add extra time or budget relative to control? All three groups attended the same schedule (four weekly one-hour sessions), read the same eight passages in the same order, answered the same comprehension questions, and were taught by the same instructor. The only differences were internal to the sessions: the explicit group received metalinguistic rule explanation and rule verbalization/error correction tasks, the input enhancement group received typographically enhanced texts with attention direction, and the control group did ordinary pre-/while-/post-reading activities. No extra instructional time, materials budget or adult support was given to the experimental groups beyond the shared sessions; the explicit grammar explanation is the treatment variable itself and occurred within the common session time. The control condition thus served as an active, time-matched comparison with equivalent educational engagement. This remains consistent with the current criterion B definition and decision tree: since no extra time or budget was present for any condition, the criterion is trivially satisfied. Criterion B is met because all three groups received the same instructional time, the same texts and the same instructor, with differences confined to the instructional technique being tested.

• Level 3 Criteria

  • R

    Reproduced

    • No independent published replication of this specific study was identified in the paper or via external search.
    • "The point is that very few studies investigated the effects of explicit instruction versus input enhancement as a method of implicit instruction on developing learners' explicit knowledge."
    • Relevant Quotes: 1) "The point is that very few studies investigated the effects of explicit instruction versus input enhancement as a method of implicit instruction on developing learners' explicit knowledge." (p. 7) 2) "A considerable number of studies have been done seperately on the effectiveness of explicit instruction and input enhancement on L2 development; however, differences in opinion exist with respect to the superiority of explicit instruction or input enhancement and more research is needed..." (p. 2) Detailed Analysis: The paper itself frames the study as filling a gap, i.e. as novel rather than as replicating or being replicated. Related studies cited (e.g., Alanen 1995; White 1998; Takahashi 2001; Moradi & Farvardin 2016; Chan 2018) examine different target structures, populations and designs and predate this paper, so they are conceptual context, not replications of this specific study. An internet search of the paper's citation record (DOI 10.1186/s40862-018-0060-4) via Semantic Scholar identified papers that cite this study, including Zeng, Xu, and Gao (2024, "The Effect of Explicit Information in Processing Instruction on Middle School Students' Acquisition of English Passive Voice"), Zhai, Du, and Xu (2026, "Effects of Input Enhancement on Chinese EFL Learners' Discourse Competence and Writing Performance"), Ahmed (2022, "Kurdish EFL Learners' Awareness of Passivization in English and Kurdish"), and several other papers on related topics such as input enhancement, explicit instruction, and passive-voice acquisition in different populations. None of these papers reproduces this study's specific design (explicit instruction vs. input enhancement vs. control, on Iranian lower- intermediate EFL learners, measuring explicit knowledge of simple present/past passive voice via UGJT and MKT); they cite it only as related background literature, not as a replication. Criterion R is not met because no independent peer-reviewed replication of this specific study was found either in the paper or through external search of the citing literature.
  • A

    All-subject Exams

    • Only custom tests of English passive voice were used; no standardised exams across all main subjects were administered, and criterion E is not met.
    • "To measure participants' explicit knowledge of the target passive voice, two valid measures including untimmed grammaticality judgement test (UGJT) and metalinguistic knowledge test (MKT) were used."
    • Relevant Quotes: 1) "To measure participants' explicit knowledge of the target passive voice, two valid measures including untimmed grammaticality judgement test (UGJT) and metalinguistic knowledge test (MKT) were used." (p. 1, Abstract) 2) "This test consisted of 15 ungrammatical sentences, of which 12 sentences were about the grammar in focus (i.e., simple present and simple past passives)..." (p. 9) Detailed Analysis: Criterion E is a prerequisite for criterion A, and E is not met because the outcome instruments are custom researcher-made tests. Moreover, the study measured only one narrow slice of one subject: explicit knowledge of English passive voice. No other school subjects (mathematics, science, first-language literacy, etc.) were assessed, and no justified specialisation exception is stated that would excuse assessing only English grammar in a general population of 13-19 year-old learners. Criterion A is not met because criterion E fails and only a single narrow grammar domain was assessed rather than all main subjects.
  • G

    Graduation Tracking

    • Measurement ended one week post-treatment with no tracking of participants to graduation, and no follow-up papers by the same authors were found.
    • "Future studies are recommended to investigate the durability or long-term effects of explicit/implicit instructional approaches on explicit knowledge of EFL learners."
    • Relevant Quotes: 1) "One week after the treatment, the posttests were administered to check the participants knowledge gain of the selected structures." (p. 10) 2) "Future studies are recommended to investigate the durability or long-term effects of explicit/implicit instructional approaches on explicit knowledge of EFL learners." (p. 16) Detailed Analysis: Criterion Y is a prerequisite for criterion G and is not met. Measurement ended one week after the four-week treatment and the authors explicitly defer any long-term investigation to future studies. No follow-up through graduation from any educational stage is reported in the paper. An internet search for subsequent publications by the same authors (Iran Bakhshandeh-Rostami and Khadijeh Jafari) tracking this cohort of Iranian lower-intermediate EFL learners was conducted using the article's citation record (DOI 10.1186/s40862-018-0060-4). No follow-up study by either author tracking these participants toward graduation was found; the papers citing this article are all by unrelated researchers working on thematically related but distinct topics, not follow-ups by the original authors on this cohort. Criterion G is not met because tracking stopped one week after the intervention with no graduation follow-up, no follow-up publications by the same authors were found via external search, and the prerequisite criterion Y is not met.
  • P

    Pre-Registered

    • The paper contains no reference to any pre-registered protocol or registry entry, and none was found via external search.
    • Relevant Quotes: 1) "Received: 3 April 2018 Accepted: 24 September 2018" (p. 17) 2) "Data will be available upon request." (Availability of data and materials section, p. 16) Detailed Analysis: The paper contains no mention of any registry (e.g., ClinicalTrials.gov, OSF, AEA registry), no registration ID, and no statement that hypotheses, methods or analysis plans were registered before data collection. As an MA-thesis-based quasi-experimental study, nothing suggests a pre-registered protocol exists. An internet search for a pre-registration record of this study, by title, authors, and DOI (10.1186/s40862-018-0060-4), found no matching entry in common trial or study registries, and the publisher's page and full text contain no registration statement or identifier. Criterion P is not met because there is no evidence of any pre-registration of the study protocol, either in the paper itself or via external search.