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03 Dec, 2013 04:10 PM


I'm a phd student at the German primate centre (DPZ). I need your help please! I encountered a problem while reading the .mwk file. When the data is imported to matlab, the feature field "alpha_multiplier" of the two stimuli: "fixation point stimulus" & the "ellipse stimulus" does not exist, as if the .mwk file does not hold that information. However it does exist for say the "dynamic random dots" stimulus. Could this reflect a problem with the core code of the program?

I'm using: Version 0.5 (73eb095)

I would really appreciate to know what you think.

All the best,

Amr Maamoun

  1. Support Staff 1 Posted by Christopher Sta... on 03 Dec, 2013 08:16 PM

    Christopher Stawarz's Avatar

    Hi Amr,

    I've confirmed that this is a problem in the implementation of these stimuli. The fixation point, ellipse, image file, and rectangle stimulus types all support the "alpha_multiplier" parameter but fail to log its value to the event stream. This appears to be a long-standing issue. Thank you for bringing it to our attention!

    This will be an easy fix on my end. Unfortunately, it won't help for any existing data files, since the values simply aren't there. However, you should still be able to determine the alpha_multiplier value for any stimulus presentation, since for a given stimulus, the alpha_multiplier parameter is either a constant (meaning the value can be read from the experiment file) or a variable (meaning the alpha_multiplier value will be equal to the value of the variable at the time the stimulus was enqueued). If you need assistance in doing this, I'd be happy to help.

    Chris Stawarz

  2. 2 Posted by Maamoun, Amr on 04 Dec, 2013 03:43 PM

    Maamoun, Amr's Avatar

    Hi Chris,

    thank you for the quick reply. What should be the next step for me? wait until a new version is issued?



  3. Support Staff 3 Posted by Christopher Sta... on 04 Dec, 2013 05:22 PM

    Christopher Stawarz's Avatar

    Hi Amr,

    I can get the fix in to the MWorks nightly build very soon. However, the nightly also includes other post-0.5 changes. If you're uncomfortable with that, then the other option is to wait for the next official release (which should go out in the next couple months).


  4. 4 Posted by Maamoun, Amr on 04 Dec, 2013 05:36 PM

    Maamoun, Amr's Avatar

    Hi Chris,

    OK. I'll work around the problem until the next version is out. Thank you again for your help!


  5. Christopher Stawarz closed this discussion on 04 Dec, 2013 06:03 PM.

  6. Christopher Stawarz closed this discussion on 17 Apr, 2014 02:41 PM.

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