# Vocabulary Retention Under Multimodal Coupling Strength Index (MCSI): Insights from Eye Tracking
## 5 Discussion
### Theoretical and Practical Implications
#### 5.3.1 Theoretical Implications: Advancing Multimodal Integration Models  
Theoretically, this study provides robust empirical validation and significant extensions to established frameworks like the Dual-Coding Theory (DCT) [4; 5] and Cognitive Theory of Multimedia Learning (CTML) [7]. While confirming the predicted superiority of multimodal input for memory encoding, our results add crucial granularity by elucidating the underlying cognitive mechanisms:  
* Attentional Optimization as a Core Mechanism: We demonstrate that the efficiency gains in multimodal learning (Group D) are directly linked to optimized attentional allocation. The observed reduction in the average saccade count (ASC) and the strategic shift in dwell time (away from text definitions towards semantically congruent pictures) provide concrete, quantifiable evidence for how synchronized audiovisual input streamlines cognitive processing. This goes beyond simply confirming DCT/CTML predictions by specifying how resource allocation is improved--through guided disambiguation and anchoring facilitated by sound.  
* Crossmodal Regulation (Inhibition): Perhaps the most significant theoretical contribution lies in revealing a sophisticated regulatory mechanism within multimodal integration, quantified by the high MCSI value (0.71) for the C/D comparison. This suggests that effective integration is not merely additive facilitation but involves crossmodal inhibition. Specifically, the auditory input appears to actively suppress redundant or inefficient processing that occurs in unimodal visual conditions (e.g., excessive focus on orthographic details in Group C). This inhibition forces a redirection of cognitive resources towards deeper semantic binding between the auditory word form and the visual representation. This finding of inhibitory dynamics adds a novel layer to our understanding of how modalities interact beyond simple facilitation, contributing new knowledge to psycholinguistic models of lexical encoding.
* Quantifying Integration Dynamics (MCSI): The development and successful application of the Multimodal Coupling Strength Index (MCSI) represent a methodological and conceptual advance. The MCSI moves beyond static group comparisons (e.g., ANOVA on recall scores) by providing a dynamic, process-oriented index that quantitatively captures the strength and quality of real-time audiovisual integration. It bridges online attentional dynamics (SD-FD, ASC) with behavioral outcomes (recall gains), offering a transferable tool for future research to quantify multisensory synergy in various learning domains. This directly addresses a key gap noted in the literature review regarding the lack of dynamic quantitative tools for assessing multimodal interactions.  
In essence, this study not only supports core tenets of the DCT and CTML but significantly refines them by uncovering the critical role of attentional optimization and revealing a previously underexplored inhibitory component in crossmodal integration dynamics during vocabulary learning.