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OpenSesame Help - 2AFC design - Non-'full factorial'

Hi everyone,

So, with this experiment I need to present a sound stimulus to the participant and they have to choose between two alternative answers. The problem i'm having is that I have multiple sets of different sounds with different answers that need to be all randomised together. For example, I have one set of sound stimuli, X, that requires answers A and B, while another set, Y, requires answers C and D, etc. But you will never need the X set to have answers C and D, or the Y set to have answers A or B. All of this also needs to be randomised together.

I have thought about putting them in blocks based on set, but I don't think it'd be as randomised as I'd like it to be.

Does anyone have a possible solution to this?

Thanks in advance!


  • Hi,

    Use inline_scripts! The problem is easily solved then. For example:

    import random
    # suppose you have the variable sound type in your loop table
    responses = dict(X=['a','b'],Y=['c','d'] # allowed response mapping
    var.required_response = random.choice(responses[var.sound_type]) # choose one randomly

    That is all.

    Hope it's useful,


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