ZeroR@CHiPSAL 2026: Two-Stage Vision-Language Adaptation with Contrastive Learning for Nepali Meme Classification
Source
Nitiz Khanal
Author
Nitiz Khanal
Date
Key takeaways · AI-distilled
The two training stages do different jobs. LoRAA cheap way to fine-tune a model by training a small add-on layer instead of changing all of the model's weights.Full definition →fine-tuningTaking a trained model and training it a bit more on your own examples so it gets better at one specific job.Full definition → with an MLP head teaches the model to emit the label; a second contrastive pass with supervised InfoNCE reshapes the backbone's embeddingA list of numbers representing a piece of text's meaning, so that similar meanings end up numerically close and can be searched.Full definition → so the classes separate.
Class imbalance gets attacked from three sides at once: oversampling the minority class, augmenting the images, and focal loss so easy examples stop dominating the gradient.
At inference they blend stage-one token probabilities with stage-two classifier scores using weights tuned on the validation set, rather than trusting either head on its own.
Binary hate detection reached 0.797 F1 while three-class sentiment reached only 0.518. The same adaptation recipe degrades sharply as the label space gets finer and more subjective.
Terms in this piece · Glossary
LoRA — A cheap way to fine-tune a model by training a small add-on layer instead of changing all of the model's weights.
multimodal — A model that works with more than text — reading images, audio, or video, and sometimes generating them too.
fine-tuning — Taking a trained model and training it a bit more on your own examples so it gets better at one specific job.
embedding — A list of numbers representing a piece of text's meaning, so that similar meanings end up numerically close and can be searched.
Why it matters
Shows a concrete alternative to OCR+translation pipelines for meme/multimodalA model that works with more than text — reading images, audio, or video, and sometimes generating them too.Full definition → classification in low-resource scripts by exploiting a VLM's native script understanding, plus a practical two-stage LoRA + contrastive (InfoNCE) recipe for handling class imbalance in shared-task settings.
Key quotes
“Our system achieved \textbf{2nd place} on hate speech detection (F1: 0.797) and \textbf{4th place} on sentiment analysis (F1: 0.518).”
“Our end-to-end approach eliminates error propagation from separate OCR and translation pipelines by leveraging the model's native Devanagari understanding.”