Millisecond Forums

You need two <trial> elements to do that:

<trial a>
/ stimulustimes = [0=fixation_cross; 500=study_board]
/ validresponse = (" ")
/ branch = [trial.b]
</trial>

<trial b>
/ stimulustimes = [0=test_board]
/ validresponse = ("B", "N")
 ...
</trial>

Dave, thank you very much for your reply! I thought it would probably solve the problem. But now I have 4 types of study boards and for each study board there are 6 possible types of test boards. I want counterbalancing to be based on test board types rather than study boards. Also, for a given test board there is a particular study board that needs to be presented before (they cannot be randomly drawn). Do you have any suggestions how blocks should be defined to take these into account?

> I want counterbalancing to be based on test board types rather than study boards.

I'm not sure what that means in concrete terms. Counter-balance what and how exactly? Between-subjects? Within-subjects? etc. A specific example would be helpful here.

> Also, for a given test board there is a particular study board that needs to be presented before (they cannot be randomly drawn).

You can pair your study- and testboard items as needed. See the "How to present stimulus pairs" topic in the documentation for details.

Also, I don't see why having a single <trial> element to display both study- and testboard would somehow avoid those two issues. If you have worked those out for the single -<trial>-element case, the solution should apply to the two-<trial>-case as well.

The problem is that stimulus pairing wouldn't work, would it? what I need is rather trial pairing - as both of the stimuli (study board and test board) require participant's response and thus two separate <trial> elements are needed. I could build a bunch of two-trial blocks and then build an experiment out of that but it does not seem to be a very neat solution as it would yield a lot of blocks...

By counterbalancing i meant within- subject design so the number of test boards of each type presented to a participant. 

> The problem is that stimulus pairing wouldn't work, would it?

The stimulus pairing works the same -- regardless of whether you have both stimuli in a single <trial> or in two separate <trial> elements.

And for "trial"-pairing, you can use conditional branching (cf. /branch attributes) to invoke the proper "testboard" <trial> element from the respective "studyboard" <trial> element.

> I could build a bunch of two-trial blocks [...]

That seems entirely unnecessary.

Try to use conditional branching as you suggested. Thank you very much for your help!

If you get stuck, post a small concrete example [1] that illustrates your intended procedure here. Then I can give you a more specific response (including example code) on how to go about implementing it.

[1] I.e. using fewer items, types and/or categories; just enough to get a sense of your intended procedure and the stimulus interdependencies.