Eye-tracking is a research method that records where on a screen or page a reader's eyes land, for how long, and in what order. In second-language research it has become the default tool for asking questions about attention, processing, and the implicit-explicit interface that earlier self-report and reaction-time methods could not answer well. Aline Godfroid is the clearest methodologist of the current wave, and her Eye Tracking in Second Language Acquisition and Bilingualism (2020) is the standard reference.
Modern infrared video-based eye-trackers record two basic events: fixations (the eye pauses on a region) and saccades (the eye jumps between regions). From fixations, researchers derive a family of measures:
| Measure | What it indexes |
|---|---|
| First-fixation duration | Initial lexical access |
| Gaze duration (first-pass) | Integration during first reading |
| Total reading time | Integration plus later reprocessing |
| Regression path duration | Difficulty resolved by looking back |
| Skipping rate | Ease of recognition |
Combined with carefully designed interest areas, these measures let researchers ask where attention went and how much work it did, with millisecond resolution.
Eye-tracking has produced empirical progress on several questions that were previously stuck at the level of argument:
The method's strengths are also its constraints. Eye-tracking works best with controlled reading and listening paradigms where the visual display is stable; it is harder in interactive, multimodal, or long-form classroom contexts. Reporting standards became a known problem in the 2010s as the method spread faster than the methodological literacy, which prompted Godfroid et al.'s (2025) Language Learning field-specific reporting guidelines.