randomizing audio files

I have been trying to set up an experiment with 100 trials. On each trial, I want to randomly present one of two audio files, followed by one of 100 words (chosen at random, but each presented only once). I have not had any problems getting SL to present a word at random (by setting up a word on each trial, rather than a stimulus list, and presenting trials randomly), but I have not figured out how to have it select one of two audio files to be randomly paired with a word each trial (and do this uniquely for each participant). I have tried to set up a stimulus list for audio files, but when I do this, the stimulus editor window does not let me specify which files should be used (there is a box that says “Location”, but it is grayed out, and I can’t type anything into the two lower boxes in the stimulus editor window).

I’m using SL 4.0.5 (Windows XP), but I had the same problem with the previous version. Can anyone help?

Hi Frank,

If you can afford to have the word presented first, the proper sequence of events within a trial would be:

  1. Word, picked from a list
  2. Sound A
  3. Sound B

In the Trial Editor, turn randomization on with the Except the first one option turned on. This will cause events 2 and 3 to be randomized.

In the Event Editor, setup Event 1 so that it would not accept any participant input. This will cause SuperLab to present it and then play Sound A or Sound B immediately.

For Event 2 and Event 3, create a feedback so that the remaining events in the trial are skipped afterwards. This is necessary to avoid having both sounds play.

Let me know if you need more assistance.

Hisham.

randomizing audio files

Hisham,

No, I cannot do the words first. On each trial, I need to do the following: 1. First, play one of two audio files (.wav, about 1 second in length) at random. 2. Immediately after the sound ends, present 1 of 100 words at random, which remains on-screen until a response is made. 3. After the response (putting the word into one of two categories), present feedback about whether the word was correctly categorized. 4. Brief interstimulus interval, then next trial. There are 100 trials, 1 for each word. I don’t want a word repeated in the experiment.
Is there any way to do that?

Thanks,

Frank

Hi Frank,

One approach is to create a stimulus list of sound files that contains multiple pseudo-randomized entries of the two sound files – but no more than you have image files. E.g. if you have 60 items in your list of words, have a separate list of audio files that contains the two files entered 30 times each. Then pseudo-randomize the order of these audio files.

Hisham.