Dear all,
I would like to optimize my design by inserting null-events between my trials (in order to better catch the HRF shape with reasonable duration of the experiment) using optseq. I'm not very familiar with this useful tool and I wonder if you could check my setup?
Here my design : I've got 12 trials per run (2 runs per participants). Each of my trial is 34s long and is composed as follow : -An instruction reminder screen of 4s -A video stimulus of 12s to 20s. This screen will be my "stimulus of interest". It's followed by a fixation cross in such a way that their cumulated durations will not exceed 20s -A question about the video followed by a fixation cross in such a way that their cumulated durations will not exceed 20s. -A jitter (a fixation cross), determined by optseq
It's a 2 (A1; A2) x2 (B1; B2) design and I'm interested in these following contrasts: A1 vs A2 B1 vs B2 (The interaction contrast will have an exploratory value in my analysis.)
In order to determine the jitters and the order of the stimuli, I set the optseq as follow:
--ntp 210\ --tr 2\ --psdwin 0 40 1\ --ev evA1B1 34 3\ --ev evA1B2 34 3\ --ev evA2B1 34 3\ --ev evA2B2 34 3\ --ecv 1 1 -1 -1\ --evc 1 -1 1 -1\ --nsearch 10000\ --nkeep 3
I'm not very confident with my setup and if it's correct? I also wonder if I correctly set the ev durations and the psdwin. The stimulus of interest is the video but I set the ev using the trial duration in order to obtain ITI jitters and psdwin to the trial duration. This results in a poor efficiency and I wonder if it's possible to better optimized this design...
Any help will be appreciated...
Regards,
Alexandre
The command line looks ok. The low efficiency is coming from the low number of events per event type.
On 9/27/16 9:52 AM, Alexandre Obert wrote:
Dear all,
I would like to optimize my design by inserting null-events between my trials (in order to better catch the HRF shape with reasonable duration of the experiment) using optseq. I'm not very familiar with this useful tool and I wonder if you could check my setup?
Here my design : I've got 12 trials per run (2 runs per participants). Each of my trial is 34s long and is composed as follow : -An instruction reminder screen of 4s -A video stimulus of 12s to 20s. This screen will be my "stimulus of interest". It's followed by a fixation cross in such a way that their cumulated durations will not exceed 20s -A question about the video followed by a fixation cross in such a way that their cumulated durations will not exceed 20s. -A jitter (a fixation cross), determined by optseq
It's a 2 (A1; A2) x2 (B1; B2) design and I'm interested in these following contrasts: A1 vs A2 B1 vs B2 (The interaction contrast will have an exploratory value in my analysis.)
In order to determine the jitters and the order of the stimuli, I set the optseq as follow:
--ntp 210\ --tr 2\ --psdwin 0 40 1\ --ev evA1B1 34 3\ --ev evA1B2 34 3\ --ev evA2B1 34 3\ --ev evA2B2 34 3\ --ecv 1 1 -1 -1\ --evc 1 -1 1 -1\ --nsearch 10000\ --nkeep 3
I'm not very confident with my setup and if it's correct? I also wonder if I correctly set the ev durations and the psdwin. The stimulus of interest is the video but I set the ev using the trial duration in order to obtain ITI jitters and psdwin to the trial duration. This results in a poor efficiency and I wonder if it's possible to better optimized this design...
Any help will be appreciated...
Regards,
Alexandre
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