How to limit the list samples OR to a certain time depending on which condition is met first.

[Paul Groot]

Oops, something went wrong when hitting the tab and enter key, so let me
restart:


One way of doing this, is to start with storing the trigger time of the
scanner in a global variable. You need to declare this variable in the
'User' tab page of the script window:

   Dim lTriggerTime as long

Then, assign the trigger time to this global variable. Assuming you have an
object that waits for the trigger signal (say a Text object called
WaitForTrigger), you should add an inline script immediately after this
object and enter the following:

   lTriggerTime = WaitForTrigger.RTTime

Then, at the end of the trial, add an inline script with the following:

   if Clock.Read>=lTriggerTime+3*60000 then
     TrialList.Terminate
   end if

(Assuming the list is called TrialList.) Make sure to set the TrialList
properties to stop after 25 trials.

One may argue that it would be easier to put the time limit in the 'Exit
List' properties of TrialLIst, and simply keep a trial counter to check for
N=25. However, for fMRI analysis it is often very convenient to store all
relevant onset and response times as output attributes, which are measured
relative to the trigger time. This is easy to do once you have the start
time available as global variable. For example, the following script (at
the end of the trial) would save the relative onsetttime as StimOnset in
the edat file:

   c.SetAttrib "StimOnset", CStr(Stim.OnsetTime - lTriggerTime)

Best,
Paul











On 12 April 2014 00:55, Paul Groot <pfc.groot at gmail.com> wrote:

> Hi Ellie,
>
> One way of doing this, it to start with storing the trigger time of the
> scanner in a global variable. You need to declare this variable in the
> 'User' tab page of the script window:
>
> Dim lTriggerTime as long
>
> Then, assign the trigger time. Assuming you have an object that waits for
> the trigger signal (say a Text object called WaitForTrigger), you should
> add an inline script immediately after this object and enter the following:
>
> lTriggerTime = WaitForTrigger.RTTime
>
> Then, at the end of the trial, add an inline script with the following:
>
> if Clock.Read>=lTriggerTime+3*60000 then
>
>
>
>
> On 11 April 2014 11:39, Ellie van Setten <ellievansetten at gmail.com> wrote:
>
>> Hi everyone,
>>
>> I am doing an fMRI experiment with children with dyslexia and controls.
>> They have to perform a rhyming task. Because control children are much
>> faster than dyslexic children I would like the response time to be variable
>> (because otherwise it would be extremely boring) The problem is that the
>> scanner needs to synchronize with the E-prime task after a fixed time (the
>> scanner sends a trigger that allows E-prime to go on). My solution would be
>> to limit the time the children can spend on the task to three minutes, then
>> have a small break with a fixation cross and synchronize and then go to the
>> next block. Only for the fast children I would like that they go to the
>> break a bit earlier, after 25 trials. So I want to pick 25 samples from my
>> task list OR I would like to stop the task and go to the break after three
>> minutes. Preferably letting the children finish the trial that was started.
>> I have tried using some in-line codes but this did not work. I hope you
>> have suggestions how I can solve this problem.
>>
>> Best,
>>
>> Ellie
>>
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