Randomizing participants pre stimulus (case 486)

[bikepunk]

I need to randomize participants into groups with different stimuli for each group. Is it possible to do that all within one input file or do I need to create 4 separate files and have my researchers randomize the participants before they open directrt? Any help is greatly appreciated.

[jsimons]

You can achieve this in a couple of different ways. First, as you suggest, you could create 4 different input files, and get the researchers to assign participants to one of the four versions (either by just running the appropriate file, or by embedding them as separate conditions of a Medialab experiment). The second is to create a single DirectRT file with all 4 versions of the experiment, and including an initial assignment item to redirect people to the appropriate version. Both would require the researchers to do the assignment into conditions.

There is a discussion of how to do this (and an example input file) in the following thread: http://support.empirisoft.com/showthread.php?t=8131

Let me know if any of this is unclear!