Go/No Go Task Timing and Accuracy Logging

[elena vella]

Hi Dear,
I'm a more than a begginer in using e-prime and I need to build a stop 
signal task to have a measure of impulsivity.
I have done the first part and it seems working but I don't know how I can 
insert the sound and change the correctanswer after it. Could you help me 
please

Thank you, best wish

Elena
Il giorno mercoledì 29 aprile 2009 18:39:23 UTC+1, katherine ha scritto:

> Hello Everyone, 
>
> I would be very grateful if you could help me with a task I am 
> programming. I am having a problem with a Stop Signal (Go-NoGo) Task. 
>
> This task has two conditions - Go (with two stimuli: < and >) and No 
> Go (Stop Trial) (also with stimuli: < and >). Each trial is timed to a 
> trigger from our scanner, which comes every 2.8 seconds. Each trial 
> lasts for two trigger periods (5.6 seconds). The Go condition is 
> working fine. The subject sees a "ready" crosshair for 500ms, then has 
> 900ms to respond to a stimulus prior to a feedback slide. In the Stop 
> condition the subject sees a "ready" crosshair for 500ms, sees a 
> stimulus, and hears a beep ("sound delay") shortly after the 
> presentation of the stimulus, which cues them to inhibit their 
> response. The timing of the presentation of the beep is dependent upon 
> a staircase. As the accuracy of the subject's responses on the Stop 
> Trials increases the time between the presentation of the stimuli and 
> beep should also increase. As accuracy decreases, the time should also 
> decrease. The goal is to keep the subject's accuracy around 50%. At 
> the beginning of the task the experimenter enters the starting time of 
> the beep presentation, based on the ending time from the subjects 
> practice run (hopefully already close to 50%). 
>
> I am having two problems with the script as it currently stands. 
> First, I am trying to set up the No Go portion (Stop Trial) of the 
> task so that it lasts for two trigger periods. Currently, if a subject 
> mistakenly responds on a No Go trial the "TrialBlankEnd2" display is 
> skipped. "TrialBlankEnd2" is a blank 1200ms display which is used to 
> lengthen the duration of the trial in order to ensure the trial lasts 
> for two trigger periods. If ""  is skipped the next trial starts after 
> only one trigger period. 
>
> I tried to achieve the same effct by using a "sleep" command, using 
> the following code: 
>
> c.SetAttrib "StimSlide2.ACC", StimSlide2.ACC 
> If StimSlide2.ACC = 0 Then 
> sleep (1300) 
> End If 
>
> I tried to insert this code in an inline file after "sound delay," but 
> it seems that when this code is implemented StimSlide2.ACC is always 
> set to zero, instead of set to 1 (which it should be set to when the 
> person correctly inhibits) The result is that the staircases I've set 
> up do not work. 
>
> What I'm looking for is a way to ensure that no matter what the 
> subject's response on a Stop Trial, the next trial does not start 
> until two trigger periods have elasped (5.6sec). If "TrialBlankEnd2" 
> is skipped, the next trial starts after one trigger period (2.8sec). 
> If I use a sleep command, it seems to throw off the accuracy count (on 
> which the staircasing is dependent). 
>
> It seems as though the script is set up correctly for the most part. 
> The staircases do work when the accuracy count works. Is there a 
> better way to set up The Stop trials that will ensure that the trials 
> have "blank time" on the end and that the accuracy counts are 
> accurate? 
>
> Thank you very much for your help with this. I appreciate it. 
>
> Katherine Koenig

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