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Appendix D Limitations and Considerations
Mobile Testing Accessory
User’s manual v.1.1- en-US
Appendix D Limitations and
Considerations
D1 Intended use
The Mobile Testing Accessory is designed to work with the Tobii Pro Nano eye tracker for mobile device testing.
D2 Light conditions
Tobii Pro recommends that eye tracking studies be performed in a controlled environment. Sunlight should be avoided
since it contains high levels of infrared light which will interfere with the eye tracker system.
Direct light from ceiling lights can affect the quality of your data. Do not place the participant directly under a light source
while performing eye tracking.
D3 Eyelashes
Because the eye tracker is positioned on the top of the screen, the Mobile Testing Accessory solution is sensitive to eye-
lashes, which can be obstructive when the
participant’s eyes are not fully open, especially if the participant is wearing mas-
cara. In rare cases, eyelashes can completely block the view of the participant´s pupils, making eye tracking impossible.
D4 Droopy eyelids
Droopy eyelids or otherwise obstructive eyelids can block the view of the
participant’s pupils. In rare cases, such eyelids
may completely block the view of the
participant’s pupils, making eye tracking impossible.
D5 Glasses and contact lenses
Participants with bifocal or progressive glasses should be screened out or asked to remove their glasses. Bifocals and pro-
gressive glasses may reduce accuracy. Contact lenses may slightly increase eye tracking interference but do not normally
introduce any error into the data. Colored or other lenses that change the appearance of the pupil or iris should be avoided
as they might make eye tracking impossible.
D6 Distance
Usage of the eye tracker is limited to the track box which means that for some participants the operating distance will be
too far to hold the device in their hand. Use of the Mobile Testing Accessory with the Mounting Arm holds and stabilizes the
mobile device.
D7 Head and hand movements
Head moments can affect the quality of the eye tracking data. The participant should hold their head still during eye track-
ing. Holding the mobile device in the
participant’s hand while eye tracking will affect the quality of the data. It is highly rec-
ommended to use the Mobile testing Accessory with the Mounting Arm to stabilize the mobile device.
