The total time is the time from when you start the scanner until the scanner turns off. The duration of the stimulus should be the just that of the stimulus. If you want to have a minimum amount of fixation between events, then use --tnullmin.

doug

On 05/05/2014 12:53 PM, Conchy PF wrote:

Hi everybody,

I have a question about optseq2.

In order to calculate ntp, I need to know the total time that my run lasts. Thus, I do not know whether I have to include in the total trial time the fixation cross time (500 ms) + event (1000 ms) + variable ISI average (1 s, ranging from 500 to 4000 ms), or not to include the variable ISI, increasing the total run time by 50% at the end.

On the other hand, I have the same dilema about the event command (ev) and the duration of the stimulus that I should set. Also, if I use the fixation cross plus event duration, they would add together 1.5 ms, while the tr is 2. According to the program's instructions, the stimulus duration must be a multiple of tr. Then, I guess that I should use to calculate the whole thing the fixation cross (500 ms) + the event (1000) + the variable ISI average (1 s). Am I right?

Thank you very much and kind regards,

C

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