Fixation-Related Potentials as Implicit Markers of Task Relevance in Data Visualization
Authors
Kathrin Schnizer (LMU Munich), Francesco Chiossi (LMU Munich), Benedikt Werner (LMU Munich), Sven Mayer (TU Dortmund University)
Presentation
- Session
- Figuring out how to do good research
- Time
- Tuesday, Nov 10, 15:12 – 15:24 (US/Eastern) · session 15:00 – 16:30
- Location
- Hall America center
Keywords
Visualization, Task Relevance, Visual Search, EEG, Eye Tracking, Fixation-Related Potentials, Physiological Computing
Abstract
Comprehending data visualizations supports informed decision-making, yet evaluation methods, such as accuracy, response time, and eye-tracking, primarily capture outcomes or overt attention rather than the cognitive processes unfolding during visualization use. Therefore, we investigate fixation-related potentials (FRPs), EEG signals time-locked to eye fixations, as implicit markers of evaluative processing that can distinguish task-relevant information processing from overt attention allocation indexed by fixation duration alone. We provide the first empirical evaluation of FRPs as relevance markers in task-driven visualization, extending their use beyond reading and visual search. In a controlled study (N=25), participants answered questions about time-series charts while we recorded responses, eye movements, and EEG. We compared fixation durations and FRP amplitudes across task-relevant and irrelevant chart areas. Relevant fixations elicited both longer durations and larger P300 amplitudes, indicating that task relevance modulates not only overt attention but also evaluative neural processing. By disambiguating decision-related processing at the single-fixation level, FRPs complement behavioral metrics and enable a time-resolved, process-level understanding of visualization use. This provides the visualization community with a complementary method for evaluating how design choices influence not just task outcomes but the cognitive processing of visual information as it unfolds.
For Practitioners
Our work is aimed at visualization researchers seeking evaluation methods that go beyond outcome measures, and at psychophysiology and neuroscience researchers interested in extending fixation-related potential (FRP) methodology, which is established in reading and scene perception, to the free-viewing, self-paced context of chart interpretation. FRPs index neural processing time-locked to individual fixations, making them a natural fit for any task where comprehension unfolds through active gaze exploration rather than a single controlled viewing period. Practitioners in visualization evaluation could use FRP markers to pinpoint the specific moment and location where comprehension succeeds or breaks down, which could inform chart redesign at the level of individual visual elements rather than whole-condition comparisons. Extending the findings to the context of adaptive visualization systems, a real-time comprehension signal could further be a candidate trigger for runtime intervention.