Using an external eye-tracker with jsPsych?

[prashantig25]

Hello All,
I have a behavioural task that runs using jsPsych. However, I would like to use the same code to conduct a lab study but using an eye-tracking set-up. I would like to use the lab's eye-tracker and not the web-cam. Is there a way to do that? How can I connect an external code so that it works with the jsPsych code? Any help is appreciated.
Thank you!!
Sincerely,
Prashanti

[jodeleeuw]

Hi @prashantig25,

This will depend on the eye tracker you are using. It'll also require adding some custom support in all likelihood.

We are working on adding Lab Streaming Layer support via a python based webserver for locally hosted jsPsych experiments. If your eye tracker supports LSL then we could talk about testing our LSL server with your eye tracker.

[jodeleeuw]

I don't think it will be possible to use cognition.run and use Eye Link at the same time. To do that you would need to somehow communicate between the eye tracker and cognition.run directly, and I can't see any way to reasonably do that.

The solution that we use for EEG in my lab is to host the jsPsych experiment locally using a python-based webserver (like Flask). JavaScript can then trigger events on the webserver, which can then communicate with the EEG equipment using python code. It looks like such a thing should be possible with Eye Link using their pylink package, but it would require some (potentially substantial) customization to get up and running.

[selinbekir]

Oh okay, good to know, I will try that. Thank you very much for your responses @jodeleeuw it's been very helpful!

[csavasegal]

I was wondering if anyone on this thread can point me towards sample code for integrating pylink with Flask? I currently have a Flask app working and linking to my hosted jspsych experiment, but am stuck on the next steps, including what pylink function to call post-calibration if I'm hoping to send a trigger on each trial (presumably in the on_load)

I'm also using the eyelink eyetracker mentioned above. Thanks so much!

[emid]

@jodeleeuw We are planning to integrate jspsych experiments with LSL. How can we test that python based webserver for locally hosted jsPsych experiments?

[derekalbert]

@jodeleeuw, did you ever get the LSL integration working? I currently have a similar use case for it. Thanks for all your wonderful work.

[fredcallaway]

I'm also trying to get this to work (with EyeLink). @csavasegal did you make progress?

[fredcallaway]

That's great to hear!

Any code you'd be willing to share would be tremendously helpful. I have a flask app already set up (using psiturk).

For calibration, I was thinking I would calibrate in javascript so that I could easily check for drift and recalibrate within a session. But this would require implementing an eyelink-compatible graphics in js (might not be so bad; this psychopy implementation is only ~200 lines). I'm curious how you handled this though. Did you just calibrate once and get good results? Or did you have participants tab out to recalibrate in pygame occasionally?

EDIT: Sorry one more question. Can you say anything more about why pygame was difficult?

[csavasegal]

I've just been splitting into runs, and calibrating at the start of each run, which has worked fine on my end!

[atakaragoz]

Hello,

Sorry to resurface a several month old thread. I've been trying to use a custom flask app for EEG as well as eyetracking with jsPsych. I've had success using pySerial to send triggers using the com port in the EEG case. Was wondering if y'all had any code you'd be willing to share for interfacing with the eye link?

On another note I ran some timing checks with a photodiode on the EEG and found that the latency between jsPsych flipping the screen and the trigger being read by the EEG rig seems to have a ~16ms jitter (this might be due to monitor refresh, although the monitor is supposedly 120hz). Was wondering if timing sensitivity ended up being an issue with either of you?

Would tremendously appreciate any help!

Best,
Ata

[vargamartonaron]

Hi,

I would like to follow up on this as well, I am currently running an online experiment using Express as backend and jsPsych as frontend, with good latencies. However, I am thinking of incorporating EEG into the paradigm, but I am worried about hosting and communicating with the hardware using a server would introduces lags to the system. In my paradigm, timings matter a lot. What do you recommend to avoid on-line communication and switch to local hardware support without introducing lags?

[fredcallaway]

Not sure if this is useful, but I put pylink trigger into my Flask app and was getting substantial latencies, in the 100ms range. The latency is highly variable, so it's tricky to account for it. Basically, if the relative timing of on-screen events and your external data source is important, I don't advise this approach. It's possible that this was specific to my setup, but my current advice is to bite the bullet and reimplement your task in pschopy or pygame :\