1　Introduction

This section elaborates on the central position of linguistic conventionality and the typical representativeness of collocation therein, reviews the definition of collocation and its critical role in native language acquisition and proficient L2 use, examines the research status of explicit and implicit L2 collocation teaching methods, identifies the deficiencies in existing explicit teaching empirical research and the neglect of learner differences, and subsequently proposes an English-Chinese contrastive collocation teaching method to fill the research gap.

2　Literature Review

This section reviews the theoretical foundations of English-Chinese contrastive teaching methods, points out that current contrastive analysis mostly remains at the surface level of language, and emphasizes the need to focus on deep cognitive contrast; it also reviews two contradictory studies on the effects of language contrastive teaching on collocation memory, and subsequently proposes that this study will employ empirical methods to verify the effects of surface-level and deep-level English-Chinese contrastive teaching modes on non-equivalent collocation memory for L2 learners of different proficiency levels, and clarifies three research questions and their theoretical and practical significance.

3　Research Design

This section introduces the overall research design. The participants were 150 first-year undergraduate liberal arts students from a university in East China, divided into high-proficiency (≥430 points) and low-proficiency L2 learners of 75 each based on CET-4 scores, with the two groups being comparable in age and gender ratio. The between-group variable was teaching mode, including a control group with traditional teaching mode, a surface contrast group focusing on linguistic structure and surface semantic differences, and a deep contrast group focusing on intrinsic semantic differences and their causes, with 50 participants in each group. Statistical analysis confirmed significant differences between the high- and low-proficiency groups, while no significant differences existed among the three groups within each proficiency level. The study proceeded in three steps: pre-test, teaching intervention, and delayed post-test, with delayed memory rather than immediate memory selected as the measurement index to better reflect long-term memory effects and avoid practice effects. Research instruments included teaching materials for 15 English-Chinese non-equivalent noun collocations, and two types of low-context sentence translation tests (Chinese-to-English and English-to-Chinese) to examine productive and receptive collocation knowledge respectively; collocations were selected through BNC corpus standard screening, pilot test familiarity verification, and controlled for word frequency, word length, and collocation equivalence. Additionally, semi-structured interviews on teaching mode adaptability and effectiveness evaluation were conducted. During the experiment, the three groups had identical teaching objectives and duration, taught by the same teacher but with different teaching modes; during post-testing, participants watched unrelated videos between the two test types to reduce mutual influence, and data were analyzed using SPSS 19.0.

4　Research Results

This section explores the effects of English-Chinese contrastive teaching modes on collocation memory for L2 learners of different proficiency levels. For low-proficiency learners, no significant differences existed among the three groups in the pre-test, while all showed significant improvement in the post-test; post-hoc comparisons revealed significant differences among the control group, surface contrast group, and deep contrast group, with the deep contrast group showing the highest learning rate (52.4%), though some students reported comprehension difficulties. For high-proficiency learners, no significant differences existed among the three groups in the pre-test, while all showed significant improvement in the post-test; post-hoc comparisons showed that the deep contrast group significantly outperformed the control group and surface contrast group, but no significant difference existed between the control group and surface contrast group, with the deep contrast group showing the highest learning rate (56.4%) and receiving positive student evaluations. Comparison between high- and low-proficiency learners found that high-proficiency learners generally achieved higher scores, with significant differences between the two in the deep contrast group but not in the surface contrast group, indicating that deep contrast teaching has better learning promotion effects for high-proficiency learners.

5　Discussion

This section explores the mechanisms through which the two types of English-Chinese contrastive teaching modes affect collocation memory for L2 learners of different proficiency levels. The study found that both modes significantly promoted collocation memory for low-proficiency learners, with the deep contrast group outperforming the surface contrast group, which can be explained by sociocultural theory, depth-of-processing theory, and involvement load theory: explicit contrastive analysis shifts learners from an "unconscious" to a "conscious" state, with deep contrast having higher involvement load on "search" and "evaluation" indices and deeper cognitive processing. For high-proficiency learners, deep contrast showed significant effects while surface contrast did not, because high-proficiency learners are already adept at actively employing contrastive memory strategies, making surface teaching intervention limited in effect, whereas deep contrast forms structural alignment with their linguistic competence and cultural knowledge. Furthermore, the difference between high- and low-proficiency learners was not significant under the surface contrast mode, as low-proficiency learners require explicit teaching intervention while high-proficiency learners can autonomously employ contrastive strategies; the difference was significant under the deep contrast mode, as high-proficiency learners can more easily engage in deep association and cognitive construction, while low-proficiency learners struggle to understand target collocations at the cognitive level.

6　Conclusion and Implications

Through empirical research, this study found that English-Chinese contrastive teaching modes have differential effects on collocation memory for L2 learners of different proficiency levels: both contrastive modes have significant learning promotion effects for low-proficiency learners; the deep contrast mode has significant effects for high-proficiency learners, while the surface contrast mode does not; no significant difference exists between high- and low-proficiency learners in the surface contrast group, while a significant difference exists in the deep contrast group. The study concludes that English-Chinese contrastive teaching is an effective explicit vocabulary teaching method, but requires appropriate adjustment according to learner proficiency, with surface contrast being more suitable for low-proficiency learners and deep contrast being more effective for high-proficiency learners.