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[open] Viewing pylink interface on participant computer

edited July 2013 in OpenSesame


I am using open sesame with pylink and I can't figure out how to access some features present in the version packaged with Experiment Builder. Specifically, I'm referring to the feature with which one can view the image of the eye (from the tracker camera) on the participant machine by pressing Enter. In the version packaged with EB, the Search Limit Box (the red circle or ellipse that surrounds the to-be-tracked eye) and the cross hairs appear on the participant machine, but they do not in the version available for building open sesame from scratch. I have the most current versions of both open sesame and pylink - I just set this computer up yesterday. Is this something that is available or can be updated in some way?



  • edited 4:46AM

    Hi John,

    Do I understand correctly that there is a version of OpenSesame packaged with SR's Experiment Builder?

    On your question about the cross hairs not appearing in the OpenSesame Eyelink setup: there is a function in libeyelink (a custom library built on top of pylink) that receives the remote camera image line by line and draws this to the screen after receiving the full image. The cross hairs do not seem to be included with this image, therefore you do not see them. This suggests that the cross hairs are not available, although I do wonder why you do see them in your other version... I'm sure Sebastiaan will be able to elaborate on that!

  • edited 4:46AM

    Hi John and Edwin,

    The crosshair and box are not drawn by pylink itself, but by the client software, in this case the OpenSesame EyeLink plug-ins. And it has simply not been implemented in the plug-ins (code). I have never perceived this as a problem, really, more of an aesthetics issue. Does this limit the functionality for you somehow?

    So this is not due to having older versions of anything, It's just a property of the EyeLink plug-ins as they are now.


    There's much bigger issues in the world, I know. But I first have to take care of the world I know.

  • edited 4:46AM

    Greeting Edwin and Sebastiaan,

    Thanks for the information. Being able to view the the cross hairs and search limit box has been convenient while trouble-shooting/debugging because it makes calibrating myself easier. For example, if the search limit box is around the wrong eye or elsewhere on the face (which does happen a bit) I can use the mouse to select the correct eye on the participant machine. But it really is convenience issue that keeps me from having to move back and forth between the two computers. I have no sense of what it would even take to implement it. If it's easy I'd request it as a new feature, but I'm not sure it's worth putting more important features on hold.

    In response to Edwin's request for clarification about what is packaged with EB. I was referring to the interface that is available when switching the camera view to the participant machine. There are subtle differences between the opensesame and EB.

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