Randomization of Stimulus Locations
Randomization of Stimulus Locations
I was just wondering if it is possible to randomize the location of certain stimuli?
I have a distractor stimuli and a target stimuli that the participant needs to locate, however the location of these stimuli need to be randomized, but they cannot overlap. Is there any way to do this? Or will I have to create a text file, with a large number of pre-made images (with distractors and targets in new locations for every image) that direct RT can randomly draw from so that the subject sees the distractors and target images in different spots throughout their session?
Check out the section from the DirectRT user's guide on "Using Random Values" or online here: http://www.empirisoft.com/directrt/help/directrt_using_random_values.htm
Since you do not want overlapping, you may wish to limit the random locations to specific values. You can do this by specifying an explicit list of x,y values to choose from or by specifying defined ranges from which to pick the values.
example of location value:
rand(100-500),rand(200,800),0
which could produce, e.g., 343,655,0 as a LOC value.
or
rand(100,200,350),rand(200,300,800),0
which could produce, e.g., 200,800,0 as a LOC value.
Hope that helps!
See also: http://www.empirisoft.com/support/showthread.php?p=10497 (v2010 and later only)
Yes that does help!
Thank you very much!
