🤖 AI Summary
This study addresses the joint distribution collapse in multimodal emotion recognition caused by EEG domain shifts and missing eye-tracking data. To tackle this, we propose GUARD, a framework that unifies domain adaptation and missing modality imputation within a single architecture. Specifically, GUARD employs gradient-weighted objectives to guide generative modules in recovering asymmetric distributions, integrates cycle-consistent flows with unsupervised calibration techniques, and leverages perceptual losses to prioritize the preservation of emotion-discriminative semantics. Experimental results demonstrate that GUARD significantly outperforms existing state-of-the-art methods. Notably, it maintains high discriminative performance even when auxiliary modalities are entirely unavailable, thereby achieving robust cross-subject emotion recognition under challenging real-world conditions.
📝 Abstract
The success of cross-subject multimodal emotion recognition hinges on maintaining the consistency of the joint data distribution across individuals. However, real-world deployment frequently triggers the \emph{asymmetric joint distribution collapse}: EEG signals suffer from severe cross-subject distribution shifts, while eye movements sensors are susceptible to packet loss and tracking failures. Existing methods treat domain adaptation and missing-modality imputation as disjoint tasks. Consequently, they fail to resolve the compounded errors when both degradations co-occur, either propagating domain shifts through imputed signals or destroying the joint decision boundary. To tackle this unified challenge, we propose GUARD (\textbf{G}radient-guided \textbf{U}nsupervised \textbf{A}symmetric \textbf{R}ecovery of \textbf{D}istributions). First, GUARD establishes a reliable anchor manifold in the source domain by employing a theoretically grounded gradient-weighted objective, which forces the robust EEG modality to preemptively entangle task-discriminative ocular features. Next, to structurally recover the collapsed joint distribution, we constrain a generative module with downstream perceptual losses, prioritizing emotion-discriminative semantics over mere signal fidelity. Finally, we formulate target-domain adaptation as an ill-posed inverse problem. By driving a cycle-consistent flow, we achieve unsupervised calibration of the recovered joint distribution directly on the target-domain manifold. Extensive experiments demonstrate that GUARD significantly outperforms state-of-the-art methods, maintaining resilient discriminative performance even under complete auxiliary modality failure. Our code and models are made publicly available to ensure complete reproducibility.