Jan Fillies
Author directory2026
Bye Bye Perspective API: Lessons for Building and Governing Measurement Infrastructure
David Hartmann | Manuel Tonneau | Angelie Kraft | LK Seiling | Dimitri Staufer | Pieter Delobelle | Jan Fillies | Anna Ricarda Luther | Jan Batzner | Mareike Lisker
Findings of the Association for Computational Linguistics: EMNLP 2026
David Hartmann | Manuel Tonneau | Angelie Kraft | LK Seiling | Dimitri Staufer | Pieter Delobelle | Jan Fillies | Anna Ricarda Luther | Jan Batzner | Mareike Lisker
Findings of the Association for Computational Linguistics: EMNLP 2026
Perspective API closes at the end of 2026, removing the de facto standard for toxicity measurement and exposing researchers’ dependence on a tool they did not control. Drawing on this case, we argue that a research field must build and govern its own measurement infrastructure rather than borrow it. Surveying 241 papers that use or study Perspective, we show what depending on it cost the research community: claims reaching past what the tool could support, results that shifted when its model was silently retrained, and disparities researchers could measure but not explain. These failures were amplified throughout the LLM lifecycle, where Perspective supplied the labels, filtered the corpora, and graded the systems trained on each, rewarding errors rather than catching them. To keep the instrument open to study after shutdown, we release Perspective scores for 5.9 million text snippets from 77 datasets. We further specify ten requirements for measurement infrastructure a field owns, and argue that what blocks such infrastructure is not technical capability but the value the field places on infrastructure work.
Algospeak, Hiding in the Open: The Trade-off Between Legible Meaning and Detection Avoidance
Jan Fillies | Ronald E. Robertson | Jeffrey Hancock
Findings of the Association for Computational Linguistics: EMNLP 2026
Jan Fillies | Ronald E. Robertson | Jeffrey Hancock
Findings of the Association for Computational Linguistics: EMNLP 2026
As large language models (LLMs) increasingly mediate both content generation and moderation, linguistic evasion strategies known as Algospeak have intensified the coevolution between evaders and detectors. This research formalizes the underlying dynamics grounded in a joint action model: when Algospeak increases, detectability and understandability decrease. Further, the concept of Majority Understandable Modulation (MUM) is introduced and defined as the modulation level at which additional evasive alteration increases detector evasion but loses comprehension for the majority of recipients. To empirically probe this trade-off, we introduce a reproducible framework that can be used to create meaning-preserving, Algospeak-style variants, based on an existing taxonomy and with tunable modulation levels. Using COVID-19 disinformation as a first proof-by-example setting, we construct a reference dataset of 700 modulated items, drawn from twenty base sentences across five modulation levels and seven strategies. We then run two linked evaluations with seven different language models: one testing for interpretation through meaning recovery and one for disinformation detection through classification. Curve fitting over modulation levels yields an estimate of the Majority Understandable Modulation threshold and enables sensitivity analyses across strategies and models, see Figure 1. Results reveal the characteristic relationships between understandability and modulation. This study lays the groundwork for understanding the dynamics behind Algospeak and provides the framework, dataset, and experimental setups described.
ToxiGAN: Toxic Data Augmentation via LLM-Guided Directional Adversarial Generation
Peiran Li | Jan Fillies | Adrian Paschke
Proceedings of the 19th Conference of the European Chapter of the Association for Computational Linguistics (Volume 1: Long Papers)
Peiran Li | Jan Fillies | Adrian Paschke
Proceedings of the 19th Conference of the European Chapter of the Association for Computational Linguistics (Volume 1: Long Papers)
Augmenting toxic language data in a controllable and class-specific manner is crucial for improving robustness in toxicity classification, yet remains challenging due to limited supervision and distributional skew. We propose ToxiGAN, a class-aware text augmentation framework that combines adversarial generation with semantic guidance from large language models (LLMs). To address common issues in GAN-based augmentation such as mode collapse and semantic drift, ToxiGAN introduces a two-step directional training strategy and leverages LLM-generated neutral texts as semantic ballast. Unlike prior work that treats LLMs as static generators, our approach dynamically selects neutral exemplars to provide balanced guidance. Toxic samples are explicitly optimized to diverge from these exemplars, reinforcing class-specific contrastive signals. Experiments on four hate speech benchmarks show that ToxiGAN achieves the strongest average performance in both macro-F1 and hate-F1, consistently outperforming traditional and LLM-based augmentation methods. Ablation and sensitivity analyses further confirm the benefits of semantic ballast and directional training in enhancing classifier robustness.
2025
A Comprehensive Taxonomy of Bias Mitigation Methods for Hate Speech Detection
Jan Fillies | Marius Wawerek | Adrian Paschke
Proceedings of the 9th Workshop on Online Abuse and Harms (WOAH)
Jan Fillies | Marius Wawerek | Adrian Paschke
Proceedings of the 9th Workshop on Online Abuse and Harms (WOAH)
Algorithmic hate speech detection is widely used today. However, biases within these systems can lead to discrimination. This research presents an overview of bias mitigation strategies in the field of hate speech detection. The identified principles are grouped into four categories, based on their operation principles. A novel taxonomy of bias mitigation methods is proposed. The mitigation strategies are characterized based on their key concepts and analyzed in terms of their application stage and their need for knowledge of protected attributes. Additionally, the paper discusses potential combinations of these strategies. This research shifts the focus from identifying present biases to examining the similarities and differences between mitigation strategies, thereby facilitating the exchange, stacking, and ensembling of these strategies in future research.
Improving Hate Speech Classification with Cross-Taxonomy Dataset Integration
Jan Fillies | Adrian Paschke
Proceedings of the 9th Joint SIGHUM Workshop on Computational Linguistics for Cultural Heritage, Social Sciences, Humanities and Literature (LaTeCH-CLfL 2025)
Jan Fillies | Adrian Paschke
Proceedings of the 9th Joint SIGHUM Workshop on Computational Linguistics for Cultural Heritage, Social Sciences, Humanities and Literature (LaTeCH-CLfL 2025)
Algorithmic hate speech detection faces significant challenges due to the diverse definitions and datasets used in research and practice. Social media platforms, legal frameworks, and institutions each apply distinct yet overlapping definitions, complicating classification efforts. This study addresses these challenges by demonstrating that existing datasets and taxonomies can be integrated into a unified model, enhancing prediction performance and reducing reliance on multiple specialized classifiers. The work introduces a universal taxonomy and a hate speech classifier capable of detecting a wide range of definitions within a single framework. Our approach is validated by combining two widely used but differently annotated datasets, showing improved classification performance on an independent test set. This work highlights the potential of dataset and taxonomy integration in advancing hate speech detection, increasing efficiency, and ensuring broader applicability across contexts.
Mapping Toxic Comments Across Demographics: A Dataset from German Public Broadcasting
Jan Fillies | Michael Peter Hoffmann | Rebecca Reichel | Roman Salzwedel | Sven Bodemer | Adrian Paschke
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing
Jan Fillies | Michael Peter Hoffmann | Rebecca Reichel | Roman Salzwedel | Sven Bodemer | Adrian Paschke
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing
A lack of demographic context in existing toxic speech datasets limits our understanding of how different age groups communicate online. In collaboration with funk, a German public service content network, this research introduces the first large-scale German dataset annotated for toxicity and enriched with platform-provided age estimates. The dataset includes 3,024 human-annotated and 30,024 LLM-annotated anonymized comments from Instagram, TikTok, and YouTube. To ensure relevance, comments were consolidated using predefined toxic keywords, resulting in 16.7% labeled as problematic. The annotation pipeline combined human expertise with state-of-the-art language models, identifying key categories such as insults, disinformation, and criticism of broadcasting fees. The dataset reveals age-based differences in toxic speech patterns, with younger users favoring expressive language and older users more often engaging in disinformation and devaluation. This resource provides new opportunities for studying linguistic variation across demographics and supports the development of more equitable and age-aware content moderation systems.
2024
Simple LLM based Approach to Counter Algospeak
Jan Fillies | Adrian Paschke
Proceedings of the 8th Workshop on Online Abuse and Harms (WOAH 2024)
Jan Fillies | Adrian Paschke
Proceedings of the 8th Workshop on Online Abuse and Harms (WOAH 2024)
With the use of algorithmic moderation on online communication platforms, an increase in adaptive language aiming to evade the automatic detection of problematic content has been observed. One form of this adapted language is known as “Algospeak” and is most commonly associated with large social media platforms, e.g., TikTok. It builds upon Leetspeak or online slang with its explicit intention to avoid machine readability. The machine-learning algorithms employed to automate the process of content moderation mostly rely on human-annotated datasets and supervised learning, often not adjusted for a wide variety of languages and changes in language. This work uses linguistic examples identified in research literature to introduce a taxonomy for Algospeak and shows that with the use of an LLM (GPT-4), 79.4% of the established terms can be corrected to their true form, or if needed, their underlying associated concepts. With an example sentence, 98.5% of terms are correctly identified. This research demonstrates that LLMs are the future in solving the current problem of moderation avoidance by Algospeak.