Running the Study
Initial Calibration of Video Feed
First, subjects will have to give permission for the Labvanced server to access their camera/webcam to record data. Once accepted, the calibration screen will appear (please allow up to 15 seconds for loading). You are looking for a video of yourself with a blue mesh over your face that moves smoothly as you turn your head and move your mouth. If the mesh seems out of sync with your actions, click “No, this does not work well” at the bottom of the screen. Otherwise, click “yes, this works well.” The study will begin after another consent screen is accepted.
Participants must have a camera or webcam with at least 1280*720 resolution in order to capture a complete eyetracking dataset. Please inform participants of this requirement at the onset of the study.
Calibration of Eyetracker
A screen with text will appear. This text can be translated for some multilingual studies, but by default looks like this:
For participants who need to wear glasses, the eyetracking may not calibrate properly, especially if the lenses are very reflective.
The next screen will ask participants about lighting. The subject’s face should be well lit from the front, without a bright light or window behind them. Too much light from the front will “wash out” a participant’s face, so be careful.
Next, participants must set their center pose (the virtual chinrest mentioned earlier). There will be 2 head poses with one round of calibration for each pose. Participants can also adjust their screen and/or camera position to be more comfortable, as they cannot change these after this step.
After clicking continue, this window will appear:
The position that the participant was in as they clicked continue on the previous screen is saved as a green mesh, which indicates the center pose/virtual chinrest. If this pose is incorrect, participants can go back and try again. If it is correct and comfortable, clicking continue will start the dynamic calibration.
Now, participants will be asked to align the blue mesh (their active face) with the green mesh (the static virtual chinrest) and hold the position for a few seconds. If they stray from this position, the calibration pauses and a notice appears at the bottom of the screen asking them to realign.
The video feed then disappears and a screen with the researcher’s chosen background color and fixation points appears. Participants are directed to look at one of the points, highlighted by a large circle that gradually shrinks as the participant gazes at it. The large circle then moves to highlight a different point on the screen, and so on until all points have been calibrated.
Next, participants are asked to move their head left and right.
Holding each pose, the dot screen appears again and is recalibrated for the left and right shifted positions. Finally, participants return to the center position for a last round of calibration with the dots. Before each trial, there is a short recalibration. If your first task involves eyetracking, there will be a short dot calibration even though the participant has just finished the overall calibration.
- If you change the background color of you frames, be sure to go to the Study Settings tab and change the overall background color of the study. This ensures that the calibration screen color matches the background color that participants will see throughout the study.
- Test the study on yourself or a lab partner to ensure you are collecting the necessary eyetracking data.
- If the same device logs into an eyetracking experiment within a few hours of having logged in previously, Labvanced may have saved the calibration data.
You can select to either skip calibration or rerun it.