Dear list,
I have an optseq2 question, and would very much appreciate your time.
I'm having difficulty calculating the required number of timepoints. I'd like to use --tnullmin and --tnullmax so as to have a null event in between each trial, with a duration of 4-8 sec. I have 16 conditions, 6 repeats/run, 2s trials, 2s TR. I computed that a run would need 16*6 = 96 timepoints for the trials. Then there would be 96 null events (to have one between each trial), so with an average 6s duration for nulls, a run needs 96*6/2 = 288 timepoints for the nulls, so 96+288 = 384 tp total. However, when I run optseq2 with these parameters, I still get nulls that are longer than 8s, and there is evidently extra time left over, since the last null event is 70 sec long. I'm using the following code:
--ntp 384 --tr 2 --psdwin 0 20 --tnullmin 4 --tnullmax 8 --nkeep 6 --o outfile --nsearch 1000 \ --ev DD 2 6 \ --ev DF 2 6 \ --ev DP 2 6 \ --ev DN 2 6 \ --ev FF 2 6 \ --ev FD 2 6 \ --ev FN 2 6 \ --ev FP 2 6 \ --ev PP 2 6 \ --ev PD 2 6 \ --ev PN 2 6 \ --ev PF 2 6 \ --ev NN 2 6 \ --ev ND 2 6 \ --ev NF 2 6 \ --ev NP 2 6
I understand that the 4-8s range may be too tight, and relaxing it is not a big deal. However, I tried 4-10s, and still has the problems with nulls > 10s and extra time at the end.
Thank you for your time,
Hanah Chapman Postdoctoral Fellow The Ohio State University