Optseq2 does not have the ability to change the identity of the stimuli during the run.
doug
Gaber, Tilman wrote:
Thank you for your quick response. Initially I had the same idea. Unfortunately, this easy solution does not work. All trials are successor of the previous and predecessor of the following trial. Therefore we can't just randomly distribute pairs of trials. The whole chain of trials has to be in proper order. ([A-B-A-A-B-B-B-A-...] = [AB BA AA AB BB BA ...]) My thinking was to somehow add these restrictions to the initial part of optseq2 algorithm and fix for null event interuptions afterwards...
Tilman
Tilman J. Gaber, Dipl.Psych. Translational Neuroscience in Psychiatry and Neurology Dpt. of Child and Adolescent Psychiatry and Psychotherapy RWTH Aachen University Neuenhofer Weg 21 52074 Aachen Germany
PHONE: +49-(0)241-80.85347 FAX: +49-(0)241-80.3335070 Email: tgaber@ukaachen.de ________________________________________ Von: Douglas N Greve [greve@nmr.mgh.harvard.edu] Gesendet: Freitag, 26. Februar 2010 18:56 An: Gaber, Tilman Cc: freesurfer@nmr.mgh.harvard.edu Betreff: Re: [Freesurfer] Optseq2 - Incorporate sequential order of trials as a factor
You can specify that there are 4 trial types (AA, AB, BA, BB), and give the duration twice that of the individual.
doug
Gaber, Tilman wrote:
Dear mailinglist recipients,
I am currently planning an optimized experiment using optseq2 and a 2x2 factors behavioral response task (Simon-task). The task consists of a pseudo-randomized series of two kinds of trials (congruent and incongruent). In addition there is a sequential factor, i.e. it is of interest whether a trial follows a trial of the same or the opposite kind. In other words there are (2x2) four different conditions where trials relate to precedent trials (AA,AB,BB,BA). Would it be possible to incorporate this sequential factor into the optseq2? I am aware that null events will fall between trials and thus interrupt trial sequences. Trials following null events would therefore be treated separately (i.e. for data analysis). In order to obtain an equal number of trials per condition, this would require increasing the number of trials depending on the number and order of null events. Currently I am able to produce a randomized order of equally balanced trials regarding trial type and sequential order (AA,AB,BB,BA). Any thoughts or suggestions are more than welcome!
Best, Tilman _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
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