Unable to draw EyeLink drift correction to screen

[Frank Verberne]

Hi Chris,

I think your experiment is doing exactly what it is being told (as computer usually do!). I don't know the nature of your EyeTracker.drifCorrection function, but it appears to me that Vizard is waiting for something that never happens. Yield should only be used for functions that return something to yield for. My guess is that your function does not return a yieldable object, so Vizard will be stuck there. Just deleting yield in front of you EyeTracker.driftCorrection function might do the trick.

By the way, the viztask.schedule function only needs at least one yield statement. You have quite a few yield statements in your function, so beware that those functions are yieldable !

[chris2307]

Thanks for the reply

I've been trying it with and without the yield statement actually and I get the same results with both. Incidentally, the only reason the yield statement is in the example above is that it happened to be what I had just tested before posting!

The experiment actually does do what I tell it to (technically), it just doesn't draw to the screen. For example, when I call my drift correction function the experiment does stop (which is good). The EyeTracker does go in to drift correction mode. The only issue is that the drift correction screen is not drawn to the screen. I can only assume that something is blocking the EyeTracker from drawing to the screen which it should be capable of doing.

My EyeTracker.driftCorrection() function simply calls the line:

pylink.getEYELINK().doDriftCorrect(960, 540, 1, 1)

The third parameter specifies that the EyeTracker should draw to the screen for me and release the screen when finished.