Explicit and Implicit Learning of College English Vocabulary: A Comparative Study and Its Pedagogical Implications

ERCT Criteria Breakdown

• Level 1 Criteria

  • C

    Class-level RCT

    • Sixty individual students were randomly divided into two groups within one university, so randomisation was at the student level, not the class or school level, and the intervention was group instruction rather than one-to-one tutoring.
    • "研究采用分层随机抽样与分组方式，将60名被试平均分为两组， 每组30人，分别为显性学习组与隐性学习组。" (p. 758)
    • Relevant Quotes: 1) "研究采用分层随机抽样与分组方式，将60名被试平均分为 两组，每组30人，分别为显性学习组与隐性学习组。" [The study used stratified random sampling and grouping to divide the 60 participants evenly into two groups of 30 each, an explicit learning group and an implicit learning group.] (p. 758, Section 2.2) 2) "A total of 60 non-English majors were selected as participants. Based on their CET-4 scores, the learners were divided into three proficiency groups: low, intermediate and advanced. Through a controlled group experiment, this study compared the differences in vocabulary learning outcomes under the two learning modes." (Abstract, pp. 756-757) 3) "以大学英语四级考试(CET-4)成绩作为划分依据，将每组被试 分为三个水平档次，每组30人中均包含三个水平层次各10人， 确保分组均衡。" [CET-4 scores were used to divide each group into three proficiency tiers, with 10 per tier in each group of 30, to ensure balanced grouping.] (p. 758, Section 2.2) Detailed Analysis: Criterion C requires randomisation at the class level or stronger (school level), unless the intervention is one-to-one tutoring or personal teaching. The paper describes stratified random sampling and assignment of 60 individual undergraduate students from a single university into two conditions. The unit of randomisation is unambiguously the individual student, not intact classes or schools. The interventions (explicit rule-based instruction versus implicit contextual input) are described as group teaching schemes, not personal tutoring, so the tutoring exception does not apply. Student-level assignment within the same institution creates exactly the contamination risk the criterion is designed to prevent. Criterion C is not met because randomisation was performed at the individual student level within one university with no valid tutoring exception.
  • E

    Exam-based Assessment

    • Outcomes were measured with an unnamed 100-point vocabulary pre/post test evidently built for the study; the only standardised exam mentioned (CET-4) was used solely to stratify participants, not as an outcome measure.
    • "注：纵轴为测试分数(满分100分，因所有被试得分均低于90分， 为优化图表可读性，图中纵轴范围设置为0~90分...)" (p. 758)
    • Relevant Quotes: 1) "注：纵轴为测试分数(满分100分，因所有被试得分均低于 90分，为优化图表可读性，图中纵轴范围设置为0~90分；误差线 代表标准差)。" [Note: the vertical axis is the test score (full mark 100; since all participants scored below 90, the axis range is set to 0-90 for readability; error bars represent standard deviations).] (p. 758, note to Figure 1) 2) "Figure 1. Comparison of pre- and post-test average scores between the explicit learning group and the implicit learning group" (p. 758) 3) "以大学英语四级考试(CET-4)成绩作为划分依据，将每组被试 分为三个水平档次..." [CET-4 scores were used as the basis for dividing each group into three proficiency tiers...] (p. 758) Detailed Analysis: Criterion E requires that outcomes be measured with a widely recognised standardised exam rather than a researcher-made instrument. The only outcome measure in this paper is a vocabulary pre-test and post-test scored out of 100 points. The paper never names this test, never identifies it with any recognised standardised assessment, and gives no information about its source, validity, or reliability; in context it is a test of the target vocabulary taught in the two learning schemes, i.e. a study-specific instrument. The one genuine standardised exam mentioned, the College English Test Band 4 (CET-4), was used only as a baseline stratification variable to form proficiency tiers, not as an outcome measure. No quote confirms use of a standardised exam for measuring the learning outcome. Criterion E is not met because the outcome was an unnamed, apparently custom-made vocabulary test rather than a recognised standardised exam.
  • T

    Term Duration

    • The paper reports no intervention start date, end date, session schedule, or interval between pre-test and post-test, so a tracking period of at least one academic term cannot be established.
    • "统计分析显示，训练后两组被试的词汇掌握水平均得到显著提升 (p ≤ 0.01)" (p. 759)
    • Relevant Quotes: 1) "统计分析显示，训练后两组被试的词汇掌握水平均得到显著 提升(p ≤ 0.01)，两种学习模式均能有效促进词汇习得" [Statistical analysis shows that after training, vocabulary mastery of both groups improved significantly (p <= 0.01); both learning modes effectively promote vocabulary acquisition.] (p. 759, Section 3.1) 2) "Figure 1. Comparison of pre- and post-test average scores between the explicit learning group and the implicit learning group" (p. 758) 3) "通过分组对照实验，对比两种学习模式下的词汇习得效果 差异。" [Through a grouped controlled experiment, the study compared differences in vocabulary acquisition under the two learning modes.] (p. 756, Chinese abstract) Detailed Analysis: Criterion T requires that outcomes be measured at least one full academic term (roughly 3-4 months) after the intervention begins, verified by quoted start and measurement dates. This paper contains no information whatsoever about the duration of the learning schemes: no start date, no end date, no number of sessions, no session length, and no interval between pre-test and post-test. The design is a simple pre-test/post-test comparison around a training phase of unreported length. With no quotable evidence that the interval from intervention start to outcome measurement reached one term, the criterion cannot be verified, and short experimental vocabulary trainings of this type are typically far shorter than a term. Criterion T is not met because the paper never states the intervention or follow-up duration, so an interval of at least one academic term is not documented.
  • D

    Documented Control Group

    • There is no untreated control group, and the two comparison groups are documented only by a bare assertion of no significant baseline differences without any demographic tables, baseline statistics, or numeric data.
    • "两组被试在年龄、专业背景、英语学习年限及英语基础上无显著 差异。" (p. 758)
    • Relevant Quotes: 1) "本研究以某高校非英语专业大学生为研究对象，共选取60人， 所有被试对象均无系统英语词汇专项训练经历。" [The participants were 60 non-English-major undergraduates at a university; none had prior systematic vocabulary training.] (p. 758, Section 2.2) 2) "两组被试在年龄、专业背景、英语学习年限及英语基础上 无显著差异。" [The two groups showed no significant differences in age, major background, years of English study, or English foundation.] (p. 758, Section 2.2) 3) "每组30人中均包含三个水平层次各10人，确保分组均衡。" [Each group of 30 contained 10 students at each of the three proficiency tiers, ensuring balanced grouping.] (p. 758) 4) "隐性学习组以语境浸泡、体验式输入为核心...不直接讲解 词汇含义与使用规则" [The implicit learning group centred on contextual immersion and experiential input... without direct explanation of word meanings and usage rules.] (p. 758, Section 2.3) Detailed Analysis: Criterion D requires detailed documentation of the control group: demographic information, baseline performance, and the treatment it received. This study has no business-as-usual control arm; it compares two active treatment groups. Even treating the implicit group as an active comparison group, the documentation is minimal. The paper asserts that the groups did not differ significantly in age, major, years of English study, and English foundation, but reports no actual demographic data (no ages, no gender breakdown, no majors), no baseline score table, and no test statistics supporting the balance claim. Baseline performance appears only as unlabelled bars in Figures 1 and 2. This falls short of the detailed description of characteristics, size, and conditions that the criterion demands. Criterion D is not met because the comparison group is documented only through an unquantified claim of baseline equivalence, with no demographic or baseline data reported.

• Level 2 Criteria

  • S

    School-level RCT

    • Randomisation was at the individual student level within a single university, with no schools or institutional units assigned to conditions.
    • "本研究以某高校非英语专业大学生为研究对象，共选取60人" (p. 758)
    • Relevant Quotes: 1) "本研究以某高校非英语专业大学生为研究对象，共选取60人" [The study took non-English-major undergraduates at one university as participants; 60 were selected.] (p. 758) 2) "研究采用分层随机抽样与分组方式，将60名被试平均分为 两组，每组30人" [Stratified random sampling and grouping were used to divide the 60 participants evenly into two groups of 30.] (p. 758) Detailed Analysis: Criterion S requires random assignment of whole schools or equivalent implementing institutions to conditions. Here all 60 participants came from a single university ("某高校", "a certain university"), and assignment to the explicit versus implicit conditions occurred at the individual student level. No multiple sites, institutions, or units were involved, let alone randomised. Criterion S is not met because the trial randomised individual students within one institution rather than randomising schools.
  • I

    Independent Conduct

    • The author team designed the learning schemes, ran the experiment, and analysed the data under their own student-innovation grant, with no mention of any external or independent evaluator.
    • "2025年度浙江省省级大学生创新创业训练计划项目“中英语义差异 情况下二语词汇显隐性学习效果对比研究”，编号S202511058113。" (p. 760)
    • Relevant Quotes: 1) "2025年度浙江省省级大学生创新创业训练计划项目“中英语义 差异情况下二语词汇显隐性学习效果对比研究”，编号 S202511058113。" [Funded by the 2025 Zhejiang Provincial College Student Innovation and Entrepreneurship Training Program project "A comparative study of explicit and implicit L2 vocabulary learning under Chinese-English semantic differences", No. S202511058113.] (p. 760, funding note) 2) "本研究以显性与隐性学习模式为核心，探究两种学习模式对 不同水平学习者二语词汇习得的影响" [This study takes the explicit and implicit learning modes as its core and explores their effects on L2 vocabulary acquisition of learners at different levels.] (p. 758) 3) "显性学习组以规则导向、有意识识记为核心，学习过程中明确 呈现目标词汇的核心含义、中英语义对比要点及典型搭配" [The explicit learning group centred on rule-oriented, conscious memorisation, explicitly presenting the core meanings, Chinese-English semantic contrasts and typical collocations of the target words.] (p. 758, Section 2.3) Detailed Analysis: Criterion I requires that the study be conducted independently of the people who designed the intervention, or at least that data collection and analysis be handled by an independent party. In this paper the same small author team, working under their own student research grant, designed both learning schemes, delivered them, administered the pre- and post-tests, and analysed the results. There is no acknowledgement of an external evaluation team, independent test administrators, or third-party oversight anywhere in the paper. Criterion I is not met because the intervention designers themselves conducted the entire study with no documented independent involvement.
  • Y

    Year Duration

    • No study duration is reported at all, so tracking over at least 75% of an academic year is not documented; criterion T already fails, which by rule also fails Y.
    • Relevant Quotes: 1) "统计分析显示，训练后两组被试的词汇掌握水平均得到显著 提升(p ≤ 0.01)" [After training, both groups improved significantly (p <= 0.01).] (p. 759) Detailed Analysis: Criterion Y requires outcome measurement at least 75% of an academic year (roughly 9-10 months) after the intervention begins. The paper gives no dates, no number of weeks, and no schedule for the training or the post-test; the entire empirical description is a pre-test, a training phase of unstated length, and a post-test. Additionally, the ranking instructions state that if criterion T (term duration) is not met, criterion Y cannot be met; T failed here for lack of any documented duration. Criterion Y is not met because no year-long (or any) tracking interval is documented and the prerequisite term-duration criterion already fails.
  • B

    Balanced Control Group

    • Both arms were active learning conditions teaching the same target vocabulary, with the instructional mode (explicit rule teaching versus implicit contextual input) being the treatment contrast itself, and no extra time or resources are reported for either arm.
    • "显性学习组以规则导向、有意识识记为核心...隐性学习组以语境 浸泡、体验式输入为核心，通过包含目标词汇的语篇、情境例句及 段落，为学生提供自然的语言输入" (p. 758)
    • Relevant Quotes: 1) "显性学习组以规则导向、有意识识记为核心，学习过程中明确 呈现目标词汇的核心含义、中英语义对比要点及典型搭配，通过 系统讲解、规则归纳与例句分析，引导学生主动理解并记忆词汇 知识" [The explicit group centred on rule-oriented conscious memorisation: core meanings, Chinese-English semantic contrasts and typical collocations of the target words were presented through systematic explanation, rule induction and example analysis.] (p. 758, Section 2.3) 2) "隐性学习组以语境浸泡、体验式输入为核心，通过包含目标 词汇的语篇、情境例句及段落，为学生提供自然的语言输入，不 直接讲解词汇含义与使用规则" [The implicit group centred on contextual immersion and experiential input, providing natural language input through texts, situational sentences and paragraphs containing the target words, without direct explanation of meanings or rules.] (p. 758, Section 2.3) 3) "通过分组对照实验，对比两种学习模式下的词汇习得效果 差异。" [Through a grouped controlled experiment, the study compared vocabulary acquisition under the two learning modes.] (p. 756) Detailed Analysis: Criterion B asks whether the comparison condition received comparable time, budget and materials, unless any extra resource is itself the treatment variable. Applying the current decision tree: no quote anywhere in the paper indicates that either arm received more instructional time, materials, technology, or budget than the other (EXTRA_RESOURCES_PRESENT is false), so the criterion is trivially satisfied. This study has no business-as-usual arm; it is a head-to-head comparison of two active instructional conditions in which both groups studied the same target vocabulary. The explicit group received systematic explanation and rule induction; the implicit group received context-embedded input of equivalent target items. The difference between arms is precisely the instructional mode being tested, which is integral to the research question (analogous to the active-control designs treated as compliant in the standard's Example 4), so even if a resource asymmetry existed it would fall under the "resources are the treatment" exception. A limitation is that the paper does not report session counts or durations for either arm, so dosage equivalence is asserted structurally rather than numerically, but no imbalance in inputs is stated or implied. Criterion B is met because no extra time, budget, or materials are reported for either arm, both groups were active conditions learning the same vocabulary, and the instructional approach itself is the treatment contrast.

• Level 3 Criteria

  • R

    Reproduced

    • This May 2026 paper reports no independent replication of its specific experiment; a targeted internet search found no citing, follow-up, or replication papers for this study.
    • Relevant Quotes: 1) "Kaivanpanah, S., Akbarian, I.H. and Salimi, H. (2021) The Effect of Explicit, Implicit, and Modified-Implicit Instruction on EFL Learners' Vocabulary Learning and Retention. Iranian Journal of Language Teaching Research, 9, 129-146." (p. 761, reference [10]) 2) "Stratton, J.M. (2023) Implicit and Explicit Instruction in the Second Language Classroom: A Study of Learner Preferences in Higher Education." (p. 761, reference [11]) Detailed Analysis: Criterion R requires that this specific study be independently replicated by a different team, in a different context, published in a peer-reviewed journal. The paper was published in May 2026 and reports a novel small-scale experiment; it cites earlier literature comparing explicit and implicit vocabulary instruction (e.g., Kaivanpanah et al. 2021, Stratton 2023), but these predate the present study and investigate the general topic rather than replicating this trial's design, sample, and materials. An internet search for the authors (Xinjie Lin, Wenjun Chen, Yanchuan Geng) together with the paper's title and topic returned only this single publication, with no citing, follow-up, or replication papers found. No replication of this particular experiment is mentioned in the paper, and given its very recent publication date none could reasonably exist yet. Criterion R is not met because no independent peer-reviewed replication of this specific study exists or is cited, and an internet search confirmed no such replication has appeared.
  • A

    All-subject Exams

    • Only English vocabulary knowledge was assessed with a custom test, no other subjects were measured, and the prerequisite criterion E is not met.
    • "Figure 1. Comparison of pre- and post-test average scores between the explicit learning group and the implicit learning group" (p. 758)
    • Relevant Quotes: 1) "Figure 1. Comparison of pre- and post-test average scores between the explicit learning group and the implicit learning group" (p. 758) 2) "对比两种学习模式下的词汇习得效果差异" [comparing differences in vocabulary acquisition under the two learning modes] (p. 756, Chinese abstract) Detailed Analysis: Criterion A requires standardised exam-based assessment across all main subjects of the curriculum, and explicitly cannot be met if criterion E fails. This study measured a single narrow outcome, knowledge of a set of English target vocabulary, using an unnamed custom 100-point test. No other subject was assessed, and no rationale invoking the specialised-programme exception is offered; these are general non-English-major undergraduates, not a vocational cohort. Since criterion E (standardised exam) is not met, criterion A automatically fails as well. Criterion A is not met because only one subject-specific custom vocabulary test was used and the prerequisite exam-based-assessment criterion already fails.
  • G

    Graduation Tracking

    • Measurement ended at the immediate post-test with no follow-up or graduation tracking; the prerequisite criterion Y is not met, and no internet search evidence of a follow-up study was found.
    • Relevant Quotes: 1) "统计分析显示，训练后两组被试的词汇掌握水平均得到显著 提升(p ≤ 0.01)" [After training, both groups' vocabulary mastery improved significantly.] (p. 759) Detailed Analysis: Criterion G requires tracking participants until graduation from their educational stage. This study ends with a single post-test administered after the training phase; there is no delayed post-test, no longitudinal follow-up, and no mention of planned follow-up publications tracking these students to graduation. An internet search for subsequent publications by the same author team (Xinjie Lin, Wenjun Chen, Yanchuan Geng) found no other papers by this group, so no evidence of graduation tracking exists in any source. Additionally, the ranking instructions state that if criterion Y is not met then criterion G cannot be met, and Y fails here. Criterion G is not met because measurement stopped at the immediate post-test with no graduation tracking found in this paper or in any follow-up publication, and the prerequisite year-duration criterion also fails.
  • P

    Pre-Registered

    • The paper contains no mention of any pre-registration, registry platform, registration ID, or protocol published before data collection, and an internet search found no registry entry for this study.
    • Relevant Quotes: No quotes referencing pre-registration exist in the paper. The only registered identifier of any kind is the funding project number: "2025年度浙江省省级大学生创新创业训练计划项目... 编号S202511058113" [2025 Zhejiang Provincial College Student Innovation and Entrepreneurship Training Program project, No. S202511058113] (p. 760), which is a grant number, not a study registration. Detailed Analysis: Criterion P requires that the full study protocol, including hypotheses, methods and planned analyses, be registered on a public registry before data collection began, with quotable evidence of the registry and timing. This paper mentions no registry (no ClinicalTrials.gov, OSF, ChiCTR, or similar), no registration date, and no published protocol. A targeted internet search on the funding project number S202511058113 returned no results, confirming it is a grant identifier and not linked to any study registry entry. A funding grant number is not a pre-registration. Criterion P is not met because no pre-registration statement or registry reference appears anywhere in the paper, and an internet search found no external registry record for this study.