Guillermo Villate Castillo, a visiting PhD student from the University of Deusto, will present his ongoing work on understanding the sources of annotator disagreement in toxicity annotation and distinguishing genuine differences in perspective from other factors.
Abstract
Annotator disagreement is increasingly recognized as a valuable source of information in subjective natural language processing tasks, motivating a shift from consensus-based annotation toward perspectivist approaches that preserve diverse human judgments. However, treating disagreement as inherently meaningful perspectival variation risks conflating genuine differences in interpretation with disagreement arising from linguistic ambiguity, missing context, epistemic uncertainty, and annotation-related factors. In this work, we challenge the assumption that annotator disagreement constitutes a homogeneous phenomenon and propose a data-centric framework for systematically identifying, characterizing, and disentangling its underlying sources in toxicity annotation. Our approach moves beyond conventional categorical and scalar toxicity labels by introducing a fine-grained, evidence-grounded annotation framework that captures multiple plausible judgments, their supporting textual evidence, interpretative mechanisms, and propositional content. Additionally, we collect annotator-level information, including demographic characteristics, lived experiences, and moral identity, alongside detailed annotation traces to investigate the relationship between individual differences and toxicity judgments. We propose an experimental methodology to examine three research questions: (1) whether richer annotation representations reveal disagreement structures that remain hidden under conventional labeling schemes; (2) how different sources of disagreement, individually and jointly, contribute to observed variation in toxicity judgments; and (3) whether residual disagreement, after accounting for identifiable data- and task-related factors, is associated with annotator characteristics. By distinguishing potentially reducible sources of disagreement from genuine perspectival variation, this work aims to provide a better understanding of human disagreement and inform the development of more reliable, interpretable, and perspective-aware toxicity annotation practices as well as a better decision-making.
When: 16/09/2026, 11:30
Where: Sala Riunioni, 1st floor