EyeLink updates

Christopher Stawarz's Avatar

Christopher Stawarz

16 Nov, 2018 05:49 PM

Hi Arash, Simon, & Archer,

The current MWorks nightly build contains several enhancements to the EyeLink interface that we discussed recently:

  1. EyeLink blink, saccade, and fixation states are now sent to MWorks and can be stored in variables.
  2. EyeLink-driven calibration is now supported.

I've attached a short example experiment that demonstrates the new features.

The blink, saccade, and fixation stuff is very simple: Just set the appropriate parameter to a variable name, and that variable will be set to true/false whenever the corresponding state is entered/exited. Now that these are available, there's probably no reason to use MWorks' eye monitor. In fact, there's probably no need to monitor saccades at all (as they are mutually exclusive with fixation). However, you will still need a fixation point to know that the monkey is fixating on the correct spot.

When updating your experiments, you should replace the existing tests for fixation:

eye_on_fixation_point and (not eye_in_saccade)

with

eye_fixating and eye_on_fixation_point

and replace the tests for broken fixation:

not (eye_on_fixation_point or eye_in_saccade)

with

not (eye_blinking or (eye_fixating and eye_on_fixation_point))

The calibration support is described in the docs and demonstrated in the example experiment. In short, you have to arrange for a fixation target to be drawn on MWorks' stimulus display when and where the tracker wants. Then, you use the new eyelink_tracker_setup action to launch the setup screen on the EyeLink host PC. At that point, your MWorks experiment is paused until you exit the setup screen. You initiate the calibration process via the EyeLink PC. The calibration results are stored on the EyeLink PC (and I believe they persist between sessions, though I'm not certain).

Note that if you're doing EyeLink-side calibration, your MWorks experiment should use the "screen gaze" coordinates (eye_rx/eye_ry/eye_lx/eye_ly), not the pupil coordinates, which are uncalibrated.

When you get a chance, please give these new features a try, and let me know if you have any questions.

Cheers,
Chris

  1. 1 Posted by Arash Afraz on 17 Nov, 2018 12:53 AM

    Arash Afraz's Avatar

    You rock Chris, thanks.

    We will try and report.

    Have a great weekend,
    Arash

    Sent via the Samsung Galaxy S7, an AT&T 4G LTE smartphone

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