N-back

[laltmann]

Here are two versions of a self-paced N-back task I have used extensively in my lab.
The first goes from 0-back to 2-back using orthographic stimuli.

The second uses visual stimuli (named for letters--since I based this on the orthographic version) and also runs from a 0-back to 2-back. I have included 2 sample stimuli. Our pilots suggested that using contiguous dot patterns and no more than 2 dots ensured non-random performance. If anybody wants the rest of the visual stimuli I will mail them or post them.

Response is via mouse button press in both.

I will post a reference for the task once I get one in press.

Lori Altmann
University of Florida

[jarvis24]

Thanks Lori! Btw, for MediaLab users, check out this link:

www.empirisoft.com/support/showthread.php?t=491

[jarvis24]

Worked with a user today on an nback task. Like the GNAT, it's helpful to be aware that "-1" can be used as a valid response option. Like indicating "RT:57,-1" with a min-max value of 1000ms will take "no response" as the response after 1000ms and proceed as if a valid key were just hit.

See

From the section on min-max settings in the users guide, or nline here:

http://www.empirisoft.com/directrt/help/directrt_minmax_setting_rt_limits.htm

An alternative to using the ! symbol is to define -1 as a valid response code on your trial. That way, only trials on which -1 is given as an option will continue automatically after the maximum time has been reached. Like other codes, if -1 is listed first, then it will be considered the correct response. This option can also be combined with the ! method if you want to define no
response as correct but have automatic continuation regardless of the response. You can think of -1 as an actual "no response" button which is pressed at the
maximum response time.

Hope it helps,
Blair