In this study we compared the latencies and amplitudes of pupillary light responses, recorded by a Tobii Pro Spark eye-tracker and a setup combining PupilEXT, a free open-source software for pupillometry, with an industrial camera. Pupil size was recorded simultaneously with both systems while illumination was provided by the Spark. Results show that neither pupillary response latencies nor amplitudes differ systematically between the two, supporting the claim that PupilEXT can be used in event-related pupillometry.

Wearable eye tracking in unconstrained settings is often compromised by slippage, yet the direct relationship between physical frame displacement and gaze error remains unexplored. This study addresses this gap combining eye tracking and motion capture to evaluate the slippage robustness of Pupil Labs Neon, Tobii Pro Glasses 3 and ViewPointSystems Lite eye trackers. Data were collected as twelve participants performed tasks involving facial expressions, induced glasses motion and locomotion. Results indicate that the Tobii Pro Glasses 3 are the most slippage-robust, maintaining an average gaze error below 2.5° regardless of movement. Conversely, the ViewPointSystems Lite exhibited large errors scaling with displacement (up to 29.3° on average) during induced motion tasks. The Pupil Labs Neon demonstrated resilience against large errors (<3.5° on average). Our findings enable researchers to anticipate the gaze error in unconstrained environments, and push manufacturers to provide realistic specifications of slippage instead of claims of “slippage-robust“ eye tracking.

We present PyeLink and SyeLink, two complementary open-source Python tools for running eye-tracking experiments and parsing data from SR Research Ltd. EyeLink eye tracking hardware. PyeLink simplifies experiment creation through plug-and-play support for multiple display backends (Pygame, PsychoPy, Pyglet) while enabling two features not available in existing tools: recording data during calibration and validation phases, and simultaneously recording raw P-CR data alongside calibrated gaze data. These enriched data files cannot be processed by existing parsers, which motivated the development of SyeLink. SyeLink parser processes recorded files and makes the data accessible through both Python API and command-line interface. SyeLink converts raw ASC data into structured JSON and CSV formats and supports visualization of calibration and validation results. Together, these tools provide a complete Python workflow for running eye-tracking experiments with enriched data recording capabilities while exposing all configurable aspects of EyeLink eye trackers.

This paper presents PyEtSimul, an open-source Python-based framework for simulating video-based eye trackers by generating synthetic eye features through geometric modeling. The framework allows flexible positioning of eyes, cameras, and light sources in 3D space, with controlled variation of eye anatomical features and camera properties. PyEtSimul generalizes corneal modeling by representing the cornea as a conic surface rather than the common sphere. It also supports non-circular pupil shapes, size-dependent pupil decentration, eyelid occlusion, and camera lens distortion. It supports systematic data generation and principled comparison of gaze estimation algorithms across calibrated and uncalibrated settings. These features enable analyses not possible with other available simulators. PyEtSimul facilitates controlled experiments with known parameters often latent in normal settings, enabling reproducible benchmarking and systematic exploration of hardware designs. By generating fully synthetic data, PyEtSimul removes privacy concerns and the need for costly hardware, making it practical for both educational and research applications.

We explore whether SAM2, a vision foundation model, can be used for accurate localization of eye image features that are used in lab-based eye tracking: corneal reflections (CRs), the pupil, and the iris. We prompted SAM2 via a typical hand annotation process that consisted of clicking on the pupil, CR, iris and sclera for only one image per participant. SAM2 was found to support better spatial precision in the resulting gaze signals for the pupil (> 44% lower RMS-S2S), but not the CR and iris, than traditional image-processing methods or two state-of-the-art deep-learning tools. Providing more frames with prompts to initialize SAM2 did not improve performance. We conclude that SAM2’s powerful zero-shot segmentation capabilities provide an interesting new avenue to explore in high-resolution lab-based eye tracking. We provide our adaptation of SAM2’s codebase that allows segmenting videos of arbitrary duration and prepending arbitrary prompting frames.

Eye tracking has been used as part of software engineering and computer science research for a long time, and during this time new techniques for machine learning (ML) have emerged. Some of those techniques are applicable to the analysis of eye-tracking data, and to some extent have been applied. However, there is no structured summary available on which ML techniques are used for analysis in different types of eye-tracking research studies.

Gaze-control and gaze-assistance in software development tools have so far been explored in the setting of code editing, but other developer activities like code review could also benefit from this kind of tool support. In this paper, we present GANDER, a platform for user studies on gaze-assisted code review. As a proof of concept, we extend the platform with an assistant that highlights name relationships in the code under review based on gaze behavior, and we perform a user study with 7 participants. While the participants experience the interaction as overwhelming and lacking explicit actions (seen in other similar user studies), the study demonstrates the platform’s capability for mobility, real-time gaze interaction, data logging, replay and analysis.

Code review is a common practice in software development and numerous studies have described different aspects of the process; its characteristics, the expectations on that process, issues around reviewer allocation, and more. However, one aspect that has not been studied to a large extent is the experience of the developers in the code review process. This is unfortunate given the significant amount of time that developers spend on this activity, where problems that degrade developers’ experience on a daily basis can create work environment issues.

A key assumption conventionally made by flexible head-mounted eye-tracking systems is often invalid: The eye center does not remain stationary w.r.t. the eye camera due to slippage. For instance, eye-tracker slippage might happen due to head acceleration or explicit adjustments by the user. As a result, gaze estimation accuracy can be significantly reduced. In this work, we propose Grip, a novel gaze estimation method capable of instantaneously compensating for eye-tracker slippage without additional hardware requirements such as glints or stereo eye camera setups. Grip was evaluated using previously collected data from a large scale unconstrained pervasive eye-tracking study. Our results indicate significant slippage compensation potential, decreasing average participant median angular offset by more than 43% w.r.t. a non-slippage-robust gaze estimation method. A reference implementation of Grip was integrated into EyeRecToo, an open-source hardware-agnostic eye-tracking software, thus making it readily accessible for multiple eye trackers (Available at: www.ti.uni-tuebingen.de/perception).

Many everyday interactions with moving objects benefit from an accurate perception of their movement. Self-motion, however, complicates object motion perception because it generates a global pattern of motion on the observer's retina and radically influences an object's retinal motion. There is strong evidence that the brain compensates by suppressing the retinal motion due to self-motion, however, this requires estimates of depth relative to the object-otherwise the appropriate self-motion component to remove cannot be determined. The underlying neural mechanisms are unknown, but neurons in brain areas MT and MST may contribute given their sensitivity to motion parallax and depth through joint direction, speed, and disparity tuning. We developed a neural model to investigate whether cells in areas MT and MST with well-established neurophysiological properties can account for human object motion judgments during self-motion. We tested the model by comparing simulated object motion signals to human object motion judgments in environments with monocular, binocular, and ambiguous depth. Our simulations show how precise depth information, such as that from binocular disparity, may improve estimates of the retinal motion pattern due the self-motion through increased selectivity among units that respond to the global self-motion pattern. The enhanced self-motion estimates emerged from recurrent feedback connections in MST and allowed the model to better suppress the appropriate direction, speed, and disparity signals from the object's retinal motion, improving the accuracy of the object's movement direction represented by motion signals.

In contemporary research, microsaccade detection is typically performed using the calibrated gaze-velocity signal acquired from a video-based eye tracker. To generate this signal, the pupil and corneal reflection (CR) signals are subtracted from each other and a differentiation filter is applied, both of which may prevent small microsaccades from being detected due to signal distortion and noise amplification. We propose a new algorithm where microsaccades are detected directly from uncalibrated pupil-, and CR signals. It is based on detrending followed by windowed correlation between pupil and CR signals. The proposed algorithm outperforms the most commonly used algorithm in the field (Engbert & Kliegl, 2003), in particular for small amplitude microsaccades that are difficult to see in the velocity signal even with the naked eye. We argue that it is advantageous to consider the most basic output of the eye tracker, i.e. pupil-, and CR signals, when detecting small microsaccades.