How to create response window for n-back task (case 10630)

Hi,
I am working on creating an n-back task, and have looked at some of the helpful samples in other forums. I am running into a problem in creating my specific version of the task. I want to display a stim (letter) for 1500ms and then have a 500ms blank screen before moving to the next trial. I would like for participants to be able to respond (or, no response) at any point during the 2000ms without altering the length of the stim or blank screen. (In other words, the trial should have a 1500ms stim and 500ms blank screen, regardless of whether the participant responds or not).

I have tried many combinations of minmax values, full/clear, and -1 codes to try to accomplish this, but can't quite find the right combination. Attached is the current attempt, which has the 1500ms stim window (but not the 500ms extended response window). Any ideas? Thanks in advance!
--Heather

PS - I am working in the 2006 version of direct RT. I think that switching styles in the middle of a trial would be a solution, but not sure whether I can make this work in my version.

Hi Heather,

You were very close to getting your input file to work. I've attached an input and style file that should be able to achieve your desired results. To show each letter for 2000ms and then move on to the next trial, you would use 0-2000! in the MinMax field of the style for each letter trial. You would then use full and clear1500 in the stim field in which you define you key presses. Use of full ensures that each letter is displayed for the full 2000ms in the MinMax field, regardless of if or when a participant presses a key. Use of clear1500 will remove the letter 1500ms after it appears and leave the remaining 500ms of each trial as a blank screen.

Please let me know if you have any questions about these files or anything else related to DirectRT.

Heather,

This forum thread also has some examples of n-back tasks if you would like to take a look at them:

[URL="http://empirisoft.com/Support/showthread.php?t=255&highlight=full+screen"][COLOR=#0066cc]http://empirisoft.com/Support/showthread.php?t=255&highlight=full+screen[/COLOR][/URL]

Jason

Thanks for your help Jason! Your file also got me close to the task I want to use (stim is presented for 1500ms, goes away and still allows a response), but there is still one issue. When I run it, DirectRT still waits for a response for each trial (instead of just moving to the next trial after 2000ms if no response is given).

I want the task to run freely on its own, so that it's standardized across participants (whether or not they respond, they should not get a break during real trial blocks, since that could affect their performance later :] ). I tried tweaking by using "!!" in MinMax with and without -1 as a response option -- and still couldn't make that happen. This is where I'm stumped. Any other ideas?

Did you install the style file I sent in the same folder as the input file that I sent? When I have it set up like that, the trials automatically progress from one to the next without needing a response.