Questions about MEG Working Memory Task - Finger Assignment and Stimulus IDs

[Sepideh Kilani]

Dear HCP Team and Community,

I hope this message finds you well. I am a researcher using the Human Connectome Project's MEG dataset, specifically for the Working Memory task. I have a couple of questions that I hope you can help clarify.

 

Question 1: Finger Assignment Counterbalancing

 the documentation does not specify details about finger assignment procedures. Specifically, I would like to know:

• Is there a counterbalancing procedure for finger assignments across subjects?
• For example, do half the subjects use their middle finger for targets and index finger for non-targets, while the other half use the reverse assignment?
• Or is the finger assignment counterbalanced within subjects across trials/blocks?

 

Question 2: Stimulus IDs

Second, you mentioned you will provide the stimulus IDs of the blocks. Could you please provide this information or guide me on where I can find it?

 

I would greatly appreciate any guidance you can provide on these matters.

Best regards,

Sepideh

[Elam, Jennifer]

Hi Sepideh,

In the description on pp. 72-73 the S1200 Reference manual indicates that for the working memory task participants were instructed to press a button with their right index finger for matching (target) pictures and press a second button with their right middle finger for non-matching (non-target) pictures across all trials/blocks. 

Therefore, I don't think finger assignment counterbalancing was performed on the HCP MEG WM task. I'm CCing two team members who might know more.

I'm not sure what you mean by Stimulus IDs. Descriptions of E-prime key variables that are column headers in e.g. 012345/unprocessed/MEG/6-Wrkmem/EPRIME/012345_MEG_Wrkmem_run1.xlsx for the tMEG tasks are in Appendix 6. 

Best,

Jenn

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From: 'Sepideh Kilani' via HCP-Users <hcp-...@humanconnectome.org>
Sent: Thursday, September 11, 2025 12:14 AM
To: hcp-...@humanconnectome.org <hcp-...@humanconnectome.org>; ord...@humanconnectome.org <ord...@humanconnectome.org>
Subject: [hcp-users] Questions about MEG Working Memory Task - Finger Assignment and Stimulus IDs

 

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