TIDC: Test-Time Intervention-based Diagnosis and Calibration for Harmful Meme Detection

Zhihui Guo, Xin Man, Hao Yin, Feiyu Chen, Jie Shao


Abstract
Harmful meme detection requires a stable understanding of how the image and the text work together. Since the text is already given as external input, a natural test is whether predictions remain stable when the corresponding visible text is removed from the image. Motivated by test-time multi-view inference, we build a text-erased reference view by keeping the external text unchanged and removing the visible text. If the model uses the external text in a stable way, this change should not greatly affect its harmfulness prediction. However, we observe clear score shifts and prediction flips, showing cross-view instability under fixed external text. We further find that the cross-view change after neutral-probe filtering is related to error risk, so it can serve as a test-time diagnostic signal. Based on this finding, we propose TIDC, a test-time framework that uses the filtered signal to calibrate the original-view score. We also provide theoretical analysis to support the diagnostic signal and calibration design. Experiments on HarM, FHM, and MAMI show that TIDC improves zero-shot performance across frozen multimodal backbones, without parameter updates or reasoning chains.
Anthology ID:
2026.emnlp-main.536
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
12346–12359
Language:
URL:
https://aclanthology.org/2026.emnlp-main.536/
DOI:
Bibkey:
Cite (ACL):
Zhihui Guo, Xin Man, Hao Yin, Feiyu Chen, and Jie Shao. 2026. TIDC: Test-Time Intervention-based Diagnosis and Calibration for Harmful Meme Detection. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 12346–12359, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
TIDC: Test-Time Intervention-based Diagnosis and Calibration for Harmful Meme Detection (Guo et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.536.pdf