Table 2.

Technical specifications of four commonly used mobile eye-trackers according to their respective manuals or, marked in parentheses, results of recent comparative studies using them in natural indoor environments (MacInnes et al., 2018)

Eye-Tracker	EyeSeeCame	Pupil labsf	SMI Eye-Tracking Glassesg	Tobii Pro Glasses 2h
Gaze accuracy (center)	0.5° (1.3°)	0.6° (0.8°)	0.5° (1.2°)	0.62° (1.4°)
Gaze precision	0.05° (0.5°)	0.08° (0.16°)	0.1° (0.19°)	0.05° (0.34°)
Calibration procedure	0-, 1-, 5-point	5- & 9-point	0-, 1-, 3-point	1-point
Sampling frequency	230 Hz	200 Hz	120 Hz	100 Hz
Signal latency	10 ms	7.5 ms	n.a.	> 10 ms

Gaze accuracy is only reported for a region ± 10° off from straight ahead in the vertical and horizontal direction, since some manufactures only provide these values. All other parameters are like those in Table 1. ^ehttps://www.sr-research.com/products/eyelink-ii/;http://www.eyeseetec.de/eyeseecam-sci/. ^fhttps://pupil-labs.com/pupil/. ^gDiscontinued. ^hhttps://www.tobiipro.com/de/produkte/tobii-pro-glasses-2/