AraProp at WANLP 2022 Shared Task: Leveraging Pre-Trained Language Models for Arabic Propaganda Detection
Paper · 2022 · Gaurav Singh
Summary
The paper describes an entry in the WANLP 2022 shared task on spotting propaganda in Arabic tweets. The author took part only in Sub-task 1, where each tweet can carry several persuasion techniques at once, so the problem is multi-label classification. The method fine-tunes eight transformer encoders on the organizers' small dataset, with no extra data, no added pre-training and no preprocessing. Two of the models are multilingual: mBERT and XLM-RoBERTa. Six are Arabic-specific: bert-base-arabic, AraBERTv1, AraBERTv2, ARBERT, MARBERT and MARBERTv2. Each model gets the same light head: averaged token embeddings, dropout, a linear projection and an independent sigmoid per label. MARBERTv2, which was pre-trained largely on tweets, gave the best micro-F1 (0.611), the official metric, and its submission placed 4th. Macro-F1 stayed very low for every model, which shows that rare techniques are barely learned. The work serves mainly as a simple, reproducible baseline and shows that matching the pre-training domain to the target genre pays off.
Key points
- Data is tiny: 504 training, 52 development and 323 test tweets. Only 18 of the 21 listed techniques actually appear in training. Loaded Language is the most frequent label at 32.8%, and about five labels account for roughly 80% of all annotations.
- The architecture is encoder → attention-mask-aware mean pooling → StableDropout (0.3) → linear layer → sigmoid, trained with binary cross-entropy.
- Training settings:
- AdamW, learning rate 5e-5, weight decay 1e-2
- batch size 4, max length 64, 10 epochs
- run on a Colab Tesla T4
- Post-hoc test scores:
- MARBERTv2 reached micro-F1 0.61116 and macro-F1 0.08175.
- bert-base-arabic had the best macro-F1 at 0.16182.
- The submitted MARBERTv2 run scored 0.600 micro-F1 and 0.105 macro-F1 (rank 4).
- Across models, the spread of macro-F1 (about 0.095) is roughly three times the spread of micro-F1 (about 0.039). The author attributes this gap to label imbalance.
Interesting ideas
- I1. Comparing the spread of macro-F1 against micro-F1 across many models works as a cheap check of whether rare classes are being learned at all, or whether the score rests on frequent labels alone.
- I2. Treating each label as its own yes/no decision, via per-label sigmoids and binary cross-entropy, lets one text carry several co-occurring tags without forcing a single choice.
- I3. Averaging token vectors while respecting the attention mask yields a fixed-size sentence vector that ignores padding, a small detail that keeps batched pooling correct.
- I4. The model whose pre-training text matched the target genre (tweets, in MARBERT/MARBERTv2) beat larger general or multilingual models, so genre fit can matter more than size.
- I5. Auditing which labels actually occur in the training split (here 18 of 21) before modelling exposes classes the system can never learn.
For Mova
How these ideas could serve Mova, our small open language model — its files, stages and tests:
- I1 (learn): Evaluation reports for role labelling or speech-act tagging could always show both averages and their cross-run spread, flagging label sets where the macro score is noisy and near zero.
- I2 (frames): Speech acts, irony and implicature markers in crate prag are not mutually exclusive, so a per-label independent scorer suits them better than one softmax over all tags.
- I3 (tree): If gparse's encoder is reused for sentence-level decisions such as clause type, mask-aware pooling avoids padding leaking into the representation.
- I4 (learn): When choosing witness parsers or teacher models for silver data on fables and school texts, prefer those trained on similar prose, and track agreement per genre.
- I5 (learn): Before training role or frame classifiers, check which VerbNet roles or frame labels are absent or very rare in silver data, and route them to rules or teacher tiers instead.
Fields, topics and concepts
📚 Shelves 6The field of science this work belongs to (OpenAlex fields).Computer Science · 16,667 worksArtificial Intelligence · 16,194 worksArts and Humanities · 16,039 worksLanguage and Linguistics · 15,891 worksSocial Sciences · 1,772 worksSociology and Political Science · 577 works
🧭 Topics 1Research subjects and languages the work is about.Semitic languages · 2,908 works
Cite
Cite as Gaurav Singh. 2022. AraProp at WANLP 2022 Shared Task: Leveraging Pre-Trained Language Models for Arabic Propaganda Detection. Proceedings of the Seventh Arabic Natural Language Processing Workshop (WANLP).
@inproceedings{singh2022araprop,
title = {{AraProp at WANLP 2022 Shared Task: Leveraging Pre-Trained Language Models for Arabic Propaganda Detection}},
author = {Gaurav Singh},
booktitle = {Proceedings of the Seventh Arabic Natural Language Processing Workshop (WANLP)},
year = {2022},
doi = {10.18653/v1/2022.wanlp-1.56},
url = {https://doi.org/10.18653/v1/2022.wanlp-1.56}
}References
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