n-back and ISI

SuperLab SuperLab 4 Support
1

Hi,

I had posted this in a reponse to another thread, but I wanted to make sure it is seen. Apologies for posting twice though!

I am designing a simple verbal n-back task, with a letter displayed for 0.5s followed by a 2.5s blank screen ISI.

I have my n-back designed as each trial containing 18 letter events for 0.5s, and each letter event is followed by a blank screen ISI for 2.5s. Is it possible to use a stimulus list instead? How do I have the stimulus list display each letter for one length of time and the blank screen for a different length of time?

Thank you!

Jessica

2

Yes, this can be done. You would create your stimulus list event and enter the time limit under the Input tab. Then, you would do the same for your ISI and then attach both events to the same trial.

3

n-back and ISI

Thank you for responding. I’m still not clear how to do this, however. I understand how to put in the time for the stimulus list. I am not clear on the following:

  1. Because of the different timing (0.5s for letter presentation, 2.5s ISI)- How do I link the events so that it alternates between the letter and the ISI?

  2. The participant can respond while the letter is being presented or they can respond during the ISI and still be correct. I know if you use the ISI function specifically, participant response is not recorded. In another post on this forum where someone had a similar question, you had suggested that the first stimulus list with the letters be duplicated but then have the letters appear off-screen to be able to record participant response. Again, how would you have the two stimulus lists alternate?

Essentially what I need is the 0.5s letter presentation and 2.5s ISI to be linked so that response time and correct/incorrect response is recorded over the course of the 3s. Sorry if I am not explaining this well. If there is a better way to set this up, I am open to suggestions.

Thank you!

Jessica

4

If you have your stimulus list and ISI within the same trial, SuperLab will present as follows:

  • First item in the stimulus list, then the ISI
  • Second item in the stimulus list, then the ISI

and so on…

The best way to visualize how SuperLab will present things at run-time is by clicking on the Experiment menu and selecting Expand Events That Use Lists. This will open a new experiment window with the contents of stimuli expanded.