HCP EVs clarification

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Hey,

We were examining the EVs in the WM task and had a few questions (some of which I believe could be relevant across tasks).

  1. What does ‘nlr’ stand for? Does ‘cor’ and ‘err’ describe the subject’s response? Was it realized to them during the experiment? Generally, is there any place we could find a key for the directory?

  2. The EVs include 3 values per signal - onset, duration, and magnitude. (a) Some durations or over 30s long - is that expected? (b) Assuming that some EVs describe the subject’s response, I would expect them to overlap (or follow) cue EV-timesteps. However, some EVs did not match. Could someone please help me clarify this?

Thanks

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Generally, is there any place we could find a key for the directory?

Yes, here: https://protocols.humanconnectome.org/HCP/3T/task-fMRI-protocol-details.html

The EVs include 3 values per signal - onset, duration, and magnitude. (a) Some durations or over 30s long - is that expected?

Yes, most of the HCP tasks used a block design paradigm. So there might be multiple trials corresponding to each line of the EV file, but all from the same condition.

(b) Assuming that some EVs describe the subject’s response, I would expect them to overlap (or follow) cue EV-timesteps. However, some EVs did not match. Could someone please help me clarify this?

I’m not quite sure I follow this, but e.g. in the WM task the cue pertains to the block, but then the correct/incorrect EVs are trial level, so they won’t necessarily be paired 1-1 with a cue.

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Thanks you. This helps a lot!

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