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Categorical judgements

  1. #1

    Categorical judgements

    Any ideas on how to set MediaLab for categorical judgements? I only want my participants to rate videos with a "yes/no" answer, ideally usign the arrow keys. I tried the "scale response" but it seems this way confines me to the numboard and specifically have to use keys #1 and #2. Any alternatives? Note: reponse has to be by keypress not mouse, as I'm looking at reponse latency too (but not to the millisecond).

  2. #2
    jarvis24 Blair Jarvis, Administrator
    In a future version of MediaLab, there will be a key mapping function so you'll be able to assign different keys to be used for the different options on a scale response. Until then though, you are limited to 1 and 2. One alternative would be to use a 9pt or 12pt scale and you could use the extremes.. such as 1 and 9 or F1 and F12 respectively. You can hide the scale by using top parameter e.g., (p12,t1000). This would give the illusion of a 2 pt categorical judgement. The only other current alternative would be to use a button box or to create a custom HTML item. The latter might be a good way to go if you or anyone in your lab knows some basic HTML.

  3. #3
    Thanks for the idea. What I actually did was 1) to use a 3 point scale, 2) to mask the buttons in the screen as you suggested (t1000 or thereabouts) 3) use a piece of cardboard to hide all keys on the numboard except #1 and #3. This should ddo the trick. Thanks a lot.

  4. #4
    jarvis24 Blair Jarvis, Administrator
    Always nice to see creative solutions using cardboard :)

  5. #5
    jarvis24 Blair Jarvis, Administrator
    [edited from support email]
    I want to be able to allow participants to use a keyboard to hit "d" or "k" for example, to indicate two different responses. (This is for a reaction time
    study.) How can I change the keyboard values from default 1 and 2 to be "d" and "k"?

  6. #6
    jarvis24 Blair Jarvis, Administrator
    Same issue as above--this is definitely on our to-do list. We just need to get the key mapping feature implemented. Until then, there isn't much you can do without going to DirectRT or by labeling the F1-F12 keys for special responses. I'm wondering if there may be a freeware application out there that would allow you to temporarily remap the keyboard through a command line execution (or batch file etc.). I'm guessing there is such a program but I'm not optimistic that it could be started and stopped using command line execution. Might be worth a search at download.com.