Millisecond Forums

You need to set up a <sound> element (if you're using WAV files) or a <video> element (if you are using some other audio format like MP3). That element can have multiple items. You then need to display it via the <trial>'s /responsemessage. One problem may be that a <trial> only may have a single /errormessage attribute (not multiple). You may thus have to /branch to a dedicated feedback trial instead of using /errormessage and/or /responsemessage. That feedback trial can display both the X <text> stimulus and the <sound>/<video> as any other trial would display any other stimuli.

Right, so the standard errormessage can only specify one stimulus. I guess I need to branch to a designated feedback trial as you suggest. However, after a few hours of fiddling around with this I can't seem to get it working. Where in the trial specification do I insert the /branch command, and how do I write the condition? The original trials are written as follows:

<trial redcongruent>
/ontrialbegin = [
    values.congruency = 1;
]
/ pretrialpause = 200
/ stimulustimes = [1=redcongruent, redreminder, greenreminder, bluereminder, blackreminder]
/ correctresponse = ("d")
/ validresponse = ("d", "f", "j", "k")
/ errormessage = true(x, 400)
/ontrialend = [
    list.responses.insertitem(trial.redcongruent.correct, 1);
    list.responses_congruent.insertitem(trial.redcongruent.correct, 1);

    if (trial.redcongruent.correct) {
        list.latencies.insertitem(trial.redcongruent.latency, 1);
        list.latencies_congruent.insertitem(trial.redcongruent.latency, 1);
    }
]
</trial>

It doesn't matter where you insert the /branch. That would only matter if there were multiple /branch attributes in the <trial>: Then they are checked in the order given from top to bottom, with the first /branch that evaluates to 'true' being executed.

<trial redcongruent>
/ontrialbegin = [
    values.congruency = 1;
]
/ pretrialpause = 200
/ stimulustimes = [1=redcongruent, redreminder, greenreminder, bluereminder, blackreminder]
/ correctresponse = ("d")
/ validresponse = ("d", "f", "j", "k")
/ errormessage = true(x, 400)
/ontrialend = [
    list.responses.insertitem(trial.redcongruent.correct, 1);
    list.responses_congruent.insertitem(trial.redcongruent.correct, 1);

    if (trial.redcongruent.correct) {
        list.latencies.insertitem(trial.redcongruent.latency, 1);
        list.latencies_congruent.insertitem(trial.redcongruent.latency, 1);
    }
]
/ branch = [if (trial.redcongruent.error) trial.errorfeedback]
</trial>                               

with

<trial errorfeedback>
/ stimulusframes = [1=x, errorsound]
/ validresponse = (noresponse)
/ trialduration = 400
/ recorddata = false
</trial>

That's awesome, thank you!