Thanks Doug. This wiki page is extremely helpful. However, my question is about individual subject responses. I could see how you could include a summary (e.g., average) value of the parametric variable across subjects in your “weight” column but it’s not clear to me how you could integrate individual subject responses to each word in the parametric modulation paradigm file? I’m imagining something like the FSGD file where a value is given for each subject, but for first-level analysis.

We have a similar design as someone else who posted a similar question (https://www.mail-archive.com/freesurfer@nmr.mgh.harvard.edu/msg19957.html). We have an event-related experiment presenting trait adjectives in terms of whether they describe themselves (SELF condition) or someone else (OTHER condition). We are interested in testing a 2x2 ANOVA to examine an interaction between self-relevance x emotional valence. Assuming you can’t integrate individual subject responses to each word in the paradigm file, would we set it up as follows?

“Usual” paradigm file:

0              1              2.5          1.0          SELF

2.5          0              2.5          1.0          FIXATION

5.0          1              2.5          1.0          SELF

7.5          2              2.5          1.0          OTHER 

Parametric modulation paradigm file:

0              1              2.5          1.0          SELFoffset

0              2              2.5          0.8          SELFslope

0              3              2.5          1.0          VALENCEoffset

0              4              2.5          2.0          VALENCEslope

(where 0.8 reflects the percentage of time the word was endorsed as self-relevant and 2.0 is the average valence rating given for that word)

And then create a contrast of 2 vs 4 to test the interaction? Would testing contrast 1 vs 0 be a test of the main effect of self-relevance and contrast 3 vs 0 the main effect of valence?

Thanks so much for your help!

Angela

From: <freesurfer-bounces@nmr.mgh.harvard.edu> on behalf of "Douglas N. Greve" <dgreve@mgh.harvard.edu>
Reply-To: Freesurfer support list <freesurfer@nmr.mgh.harvard.edu>
Date: Thursday, July 28, 2022 at 10:25 AM
To: "freesurfer@nmr.mgh.harvard.edu" <freesurfer@nmr.mgh.harvard.edu>
Subject: Re: [Freesurfer] FSFAST first level covariates

Yes, see https://surfer.nmr.mgh.harvard.edu/fswiki/FsFastParametricModulation

On 7/25/2022 6:56 PM, Angela Fang wrote:

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Hi Freesurfer community,

I have run participants through an event-related fMRI task in which subjects rate whether trait adjectives are descriptive of themselves or not, and afterwards asked them to rate each trait word on emotional valence. Is it possible to include these individual level subjective ratings of emotional valence as covariates in the first level contrast in FSFAST? If so, how?

Thanks,

Angela

---

Angela Fang, Ph.D.

Assistant Professor
Department of Psychology

University of Washington

Lab website: MailScanner has detected a possible fraud attempt from "secure-web.cisco.com" claiming to be www.uwconnectlab.com

Pronouns: she, her, hers

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