Early Fusion with Contrastive Learning: A Lightweight Alternative for Multi-modal Classification
Summary
Leading multimodal classifiers usually depend on large, computationally expensive architectures. This paper asks whether a much smaller design can reach similar accuracy. The authors build a framework around early fusion. Pretrained encoders turn each modality into an embedding: CLIP for text, images and video frames, AutoGluon-Tabular for tables, CodeBERT for code, and Wav2Vec for audio. These embeddings are concatenated and passed to a compact feed-forward classifier. Because text and image tend to be the strongest signals, weaker modalities first go through a residual projector. That projector is trained with a contrastive objective that pulls each modality's embedding toward the matching text and image embeddings, using hard negative mining. Tests on three kinds of multimodal classification datasets show the lightweight model matching, and sometimes beating, much larger state-of-the-art systems. Per-dataset scores were in a part of the paper not available for this summary. The work matters because it gives an accessible baseline for settings where compute or budget is limited.
Key points
- Model size: the early-fusion model has about 1M trainable parameters, compared with 355M for the AutoGluon baseline.
- Classifier: two blocks, each made of a fully connected layer, batch normalization and ReLU, trained with cross-entropy loss. Video is represented by 15 frames encoded with CLIP and then max-pooled.
- Projector: a linear layer with Tanh activation, followed by dropout and a residual connection back to the input features.
- Alignment loss: a modified NT-Xent loss built on temperature-scaled cosine similarity. Only the top-k hardest negatives per sample are used, which reduces noise.
- Code: released for reproducibility at github.com/fWern/MultimodelClassification.
Cite
@inproceedings{wernlein2026early,
title = {{Early Fusion with Contrastive Learning: A Lightweight Alternative for Multi-modal Classification}},
author = {Wernlein, Felix and Jana, Abhik and Sikdar, Sandipan},
booktitle = {Proceedings of the Fifteenth Language Resources and Evaluation Conference},
year = {2026},
doi = {10.63317/3ioe7epfs78m},
url = {https://doi.org/10.63317/3ioe7epfs78m}
}References
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