Stop-Signal-Task

Hi there,

in our lab, we are investigating executive functions in children. In a new project, we would like to use a stop-signal task. Has anybody programmed this task with directRT before or any idea how to do it? (kjdere2 asked the same question in the "sharing area" last year).

Let me shortly describe the task for you:
The stop-signal tasks consists of 2 kinds of trials: go-trials (75%) and stop-trials (25%) which are randomly presented to the subject.

The go-trials are simple choice-reaction tasks (e.g., the subject has to press a certain response key when the stimulus is a square; when the stimulus is a circle, the subject has to press another key)
On stop-trials, after the go-stimulus (e.g. circle or square) an auditory tone or visual warning signal is presented after a VARIABLE delay, which tells the subject to withhold his/her response to the go-stimuli. The tricky thing about the stop signal task is this variable stop-signal-delay (SSD), thus the delay between the primary go-stimulus and the stop-signal. The SSD starts for example at 250ms on the first stop-trial.
a) If the subject succeeds to inhibit his/her response, the next stop-trial becomes more difficult by increasing the SSD on the next stop-trial by 50ms.
b) If the subjects fails to inhibit his response, the next stop-trial becomes more easy by decreasing the SSD by 50ms.

Does anybody know how to handle this "adjustment" of the SSD?

Thanks a lot,
Johanna

Although it isn't an ideal solution, it may be easiest to use a combination of Skips, Jumps, and then simply copy / paste sections of your excel file.

If the SSD is to be increased, you could simply skip to an area in which the time-delay is higher.

It may also be noted that we're currently trying to implement an easier method to complete this task within DirectRT 2010. The following link will direct you to a thread in which the feature has been requested:
[url]http://www.empirisoft.com/support/showthread.php?t=621[/url]