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Help selecting an eye tracker

tsummer2tsummer2 Posts: 15

Currently my lab is using the EyeTribe to record pupillometry data while participants perform an attention task with their heads on a chinrest. We are wondering if it would be worth our money (willing to spend any amount) to invest in a "better" tracker. Could the quality of pupil diameter data really be improved that much by a more expensive tracker? The only benefit I can think of is that the EyeTracker provides pupil diameter in arbitrary values, while nicer trackers can report this information in millimeters or something (even though this really doesnt matter since most pupillometry studies are interested in relative size). We would love any suggestions. Thanks!

Comments

  • sebastiaansebastiaan Posts: 2,403

    Hi,

    Could the quality of pupil diameter data really be improved that much by a more expensive tracker?

    If you're only interested in measuring pupil size, then buying a more expensive eye tracker may not be worth it. Gaze position is much more difficult to determine than pupil size, and in quality of gaze position is therefore where you will find most of the differences between cheap and expensive eye trackers. And in sampling frequency, of course; but again, because pupil size is a slow signal, you won't gain much with a higher sampling frequency.

    The only benefit I can think of is that the EyeTracker provides pupil diameter in arbitrary values, while nicer trackers can report this information in millimeters or something (even though this really doesnt matter since most pupillometry studies are interested in relative size)

    Some expensive eye trackers do indeed provide natural units (i.e. millimeters of pupil diameter), but most don't. A common trick is to calibrate yourself, by holding a fake pupil with a known diameter in front of the camera. Based on the recorded pupil size, you then determine a scaling factor.

    This is really easy to do with some eye trackers, like the EyeLink. But I've heard that the EyeTribe is not easy to fool, that is, it's difficult to have it record pupil size for a fake pupil/ eye/ face—so it might need some tweaking and trying out before that works.

    Cheers!
    Sebastiaan

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