Due to the low accuracy and noisy data of common eye trackers, virtual gaze-activated targets used for gaze interaction tend to be large, so they can be easily fixated and selected. Therefore, a full-size virtual keyboard with 30 to 40 keys may take a large portion of the screen space. If one simply reduces the keyboard size into a higher density interface, selections would become unreliable. In this paper we present XTar, an expandable target interface that uses an entropy-based algorithm to expand and improve the robustness of target selection in high density interfaces. Results from a pilot user experiment show that typing using a dwell-time linear XTar keyboard is as fast as a 3 row QWERTY keyboard with fixed size keys, with similar low error rate, using about 1/3 of the QWERTY keyboard area.
BibTeX
@article{10.1145/3729408,
author = {Gonzales, Candy T and Morimoto, Carlos H},
title = {XTar: entropy-based target expansion for high density gaze-based interfaces},
year = {2025},
issue_date = {June 2025},
publisher = {Association for Computing Machinery},
address = {New York, NY, USA},
volume = {8},
number = {2},
url = {https://doi.org/10.1145/3729408},
doi = {10.1145/3729408},
abstract = {Due to the low accuracy and noisy data of common eye trackers, virtual gaze-activated targets used for gaze interaction tend to be large, so they can be easily fixated and selected. Therefore, a full-size virtual keyboard with 30 to 40 keys may take a large portion of the screen space. If one simply reduces the keyboard size into a higher density interface, selections would become unreliable. In this paper we present XTar, an expandable target interface that uses an entropy-based algorithm to expand and improve the robustness of target selection in high density interfaces. Results from a pilot user experiment show that typing using a dwell-time linear XTar keyboard is as fast as a 3 row QWERTY keyboard with fixed size keys, with similar low error rate, using about 1/3 of the QWERTY keyboard area.},
journal = {Proc. ACM Comput. Graph. Interact. Tech.},
month = may,
articleno = {28},
numpages = {15},
keywords = {gaze selection, target expansion, entropy, eye tracking, eye gaze-based interfaces}
}