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OpenSesame backend for eyetracker: xpyriment vs legacy


I am trying to set up an experiment with Tobii eyetracker and OpenSesame. I see that most eyetracking experiments use the xpyriment backend, and I am wondering if there is a specific reason for this.

In my initial testing, I seem to get more stable results and less errors when using the legacy backend instead of xpyriment.

Is there any special reason I should choose one over the other?




  • Hi,

    In case anyone else will wonder about this, I found an good reference here:

    Dalmaijer, E. S., Mathôt, S., & Van der Stigchel, S. (2014). PyGaze: an open-source, cross-platform toolbox for minimal-effort programming of eyetracking experiments. Behavior Research Methods, 46(4), 913–921.

    Note that the legacy backend is built on PyGame. The authors explain that PsychoPy is better suited for very precise measuring of time, and more complex stimuli:

    "Both PyGame and PsychoPy are complete libraries [...]. The main difference between the two is that PsychoPy supports hardware-accelerated graphics through OpenGL. In practice, this means that a great number of complicated stimuli, such as drifting Gabors, can be created within the time needed for a single frame refresh. In addition, PsychoPy retrieves millisecond-accurate information on the actual refresh time. This makes PsychoPy the package of choice for complex paradigms that require heavy processing or a high degree of temporal precision..."

    The paper includes further details and also a comparison of the 2 libraries' performance.



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