I need to super-impose two polygons, one polygon on top of another. To do this, I need to make the background transparent. This can be done for a pgn file, but apparently DirectRT cannot take pgn files.
A possibility would be to do the super-imposition outside of DirectRT, but the polygons are made of 2 sets of 30, which would require pre-randomization of 900 trials.
I would be grateful for any advice.
That's tricky because DirectRT does not currently support transparency. You could possibly do this in MediaLab--do you have access to it? And what are the timing requirements--e.g., are subjects reacting with keyboard response to each combination, or are they simply viewing them and then responding later on? With MediaLab, a custom item could likely be set up to present the combinations using HTML--a context that would support the transparency requirements. Just a thought. But again, I can't see a quick work-around in DirectRT short of, as you suggested, the rather tedious task of pre-combining the combinations as single stimuli.
The subjects are reaction with keyboard responses to each combination and RTs are being measured as the dependent variable.
I'm not familiar with mediaLab--would it indeed be possible?
Are you expecting a fairly uniform RT collection, such as 500-1000ms with some minor variation? Or something like 1000-5000ms with a relatively large variation in RTs?
Hi
More like 500-1000ms with some variation
Please let me know if you need further assistance with this matter.