Hi Manasij, Sorry for the delay in responding. I missed this message to the mailing list.
I understand your confusion here. The cue was included in the onset and duration of the EVs in our analyses of the earlier data release for the 2013 paper. However, the timing of the EVs in the publicly released data makes it clear that the onset is the first trial in the block and the duration does not include the cue. I’m not exactly sure when that change occurred. There were issues with EVs for other tasks before the 500 subject release, and this change was probably included when we were fixing those errors. However, I don’t think that this change is really consequential. In piloting the current HCP-Lifespan project, I analyzed our pilot data two different ways: including the cue in the block versus not including the cue in the block. The results of those two analyses were virtually identical for the relevant contrast of FACE-SHAPE. This makes sense because, in the analysis including the cue, the cue is present in both conditions and “cancels out” in the difference contrast. In the analysis excluding the cue, the cue is also effectively “cancelled out” because it was never present in either condition. I didn’t follow your last statement (#2 below), but I’ll try to address it anyway. It doesn’t really matter that the EV duration in the text file is longer than the scan (image file). Because the scanner acquisition ends at the end of the last trial in that block, you can’t tell the difference between a 12 sec, 18 sec, or 200 sec duration that occurs after the scanner has stopped. As such, the Feat design ignores timepoints that occur after the end of the timeseries image. Hope that helps, --Greg ____________________________________________________________________ Greg Burgess, Ph.D. Staff Scientist, Human Connectome Project Washington University School of Medicine Department of Psychiatry Phone: 314-362-7864 Email: [email protected] > On Sep 25, 2017, at 3:43 PM, Manasij Venkatesh <[email protected]> wrote: > > Hi, > > The task description for the EMOTION data is as follows: > > This task was adapted from the one developed by Hariri and colleagues which > had shown evidence as a functional localizer (Hariri et al., 2002) with > moderate reliability across time (Manuck et al., 2007a). Participants are > presented with blocks of trials that either ask them to decide which of two > faces presented on the bottom of the screen match the face at the top of the > screen, or which of two shapes presented at the bottom of the screen match > the shape at the top of the screen. The faces have either angry or fearful > expressions. Trials are presented in blocks of 6 trials of the same task > (face or shape), with the stimulus presented for 2 s and a 1 s ITI. Each > block is preceded by a 3 s task cue (“shape” or “face”), so that each block > is 21 s including the cue. Each of the two runs includes 3 face blocks and 3 > shape blocks. However, there was a bug in the E-prime script for this task > such that the task stopped short of the last three trials of the last task > block in each run. To promote comparability across participants, we decided > not to fix the bug (given that a number of subjects had already been run > before it was detected) as we thought it would have minimal impact on the > data. In phase I, we compared this task to one using negative and neutral > IAPS pictures (see Supplemental Materials). > > > A typical EV file looks like this (fear.txt) > 32.053 18 1 > 74.196 18 1 > 116.338 18 1 > > The block length indicated is 18, where as the description says 21. My > question is if the onset listed here is that of the first trial or of the cue. > > My confusion is based on 2 things: > 1. For the working memory (WM) data, the block lengths include the time of > the cue. The onsets are that of the cue. > 2. The bug reported says the last 3 trials are cut-off/ missing, and if I do > the math it seems this can't be the onset of the cue. I wanted to confirm > this. > > Please let me know. > > Sincerely, > Manasij > > > _______________________________________________ > HCP-Users mailing list > [email protected] > http://lists.humanconnectome.org/mailman/listinfo/hcp-users > ________________________________ The materials in this message are private and may contain Protected Healthcare Information or other information of a sensitive nature. If you are not the intended recipient, be advised that any unauthorized use, disclosure, copying or the taking of any action in reliance on the contents of this information is strictly prohibited. If you have received this email in error, please immediately notify the sender via telephone or return mail. _______________________________________________ HCP-Users mailing list [email protected] http://lists.humanconnectome.org/mailman/listinfo/hcp-users
