Use two eye-trackers at the same time in OpenSesame

Comments

• eduard

  July 2020

  Hi Lisa,

  As you describe yourself, you can't have two eye trackers running in the same experiment with Opensesame and Pygaze plugin. I am not sure though whether this generally impossible, or could work if you used direct coding (e.g. in Python, maybe even with the Pygaze library). But I would imagine you would need to make sure that the eyetrackers run on different I/O ports or channels. Otherwise they would interfere. Again, whether this is generally possible or not, I don't know.

  Hope this helps a bit.

  Eduard

  
• lspitzer

  August 2020

  Hey Eduard,

  thanks a lot for your reply! I am currently trying to solve the problem by implementing "Lab Streaming Layer" somehow to synchronize the eye-trackers (unfortunately, there is no direct support for the Gazepoint eye-tracker I want to use). If this does not work, I will definitely try using direct coding as you suggested.

  Best, Lisa
• lspitzer

  August 2020

  Hello again!

  I am currently trying the option suggested by Eduard, to use direct coding to include multiple eye-trackers at the same time in OpenSesame. Yet, I am still struggling with this. I am able to use the functions described in the OpenSesame PyGaze documentation (https://osdoc.cogsci.nl/3.2/manual/eyetracking/pygaze/#function-overview), but for using them I need to embed the PyGaze init-item (plug-in) first. When I try to embed two init-items (one for the Gazepoint eye-tracker and the other one for the Tobii eye-tracker) I get the error message that I can only include one init-item. Does anyone know how to inititate eye-trackers using the inline python script?

  I can't even record one eye-tracker with this method. Here is an example of how I tried to call the function, but it does not work:

  

  Thank you in advance!!

  Best, Lisa
• eduard

  August 2020

  Hi Lisa,

  I don't think you can directly use the pygaze functions. As these are also used by the plugins in Opensesame. Instead, I would recommend you go through the source code of Pygaze and try to follow how connections with the Eyetracker is established. Based on that code you might be able establish a connection with the trackers. For example, here is the main code how Pygaze interacts with Eyelink trackers: https://github.com/esdalmaijer/PyGaze/blob/master/pygaze/_eyetracker/libeyelink.py

  But again, to be clear, even though I proposed this idea, I have no idea whether it works. In fact, I have the hunch it won't, but please prove me wrong.

  Good luck!

  Eduard

  
• lspitzer

  August 2020

  Hi Eduard,

  I tried some different things and actually found a method that worked (but not in OpenSesame)! Instead, I used Rapunzel and wrote the code manually. I used an example experiment provided in the pygaze documentation ("simple tracker experiment") as orientation, and manually wrote the code. By using the pygaze functions via code, I could define two eye-trackers at the same time. For example:

  

  Thank you very much for your help!

  Best, Lisa
• eduard

  August 2020

  Very cool! If you eventually make your experiment work, it would be nice if you could post your code/experiment. This might be interesting for other users.

  Thanks