Visible contrasts but None significant in mne_nirs

Support & Discussions
1

Hi,
I am trying to process some tasks observation data compared to a condition of Rest for a subject in mne_nirs.
The code I came up with works just fine, as it plots some interesting contrasts, that, by eye, seem very significant. However, when I convert the contrast to a dataframe, none of the channels seems to have significance, with p_values not event close as the normal threshold.
Here an example of one contrast topoplot:

Contrast_hbo_Lavarsi i capelli
Contrast_hbo_Lavarsi i capelli1200×700 93 KB

And here are the p_values associated to the channels:
[0.24624852332069663,
0.2250108543570854,
0.20660119721595177,
0.3193874762007398,
0.14375251210121004,
0.3257796307598987,
0.40278250897638934,
0.5102339330202065,
0.2699080479219398,
0.3285143871425482,
0.26587728398651855,
0.30688918131104537,
0.25310540190691955,
0.45614819477589474,
0.7883066135221217,
0.5860130845919118,
0.383218032622168,
0.31109923276180884,
0.24898148432969192,
0.09698710171326916,
0.2986409826681342,
0.36707117024939206,
0.0762459011253407,
0.3920105621786507,
0.0864802720438016,
0.2626391382284704,
0.6437294393693793,
0.6113977367975962,
0.3190955486578235,
0.27825665378326553,
0.23596645390137144,
0.3382480010118948]

Someone has an idea of why I have these not signicant values, while from the figure there seem to be many significant?
Moreover, does contrast in mne_nirs utilize some kind of correction by default?

2

If the p-value is large, then it must mean that the variance in the set of number you give it is large than the difference in means that you are plotting. If the set of numbers you give to the t-test come from different trials, then it must mean that there is a large variance in the signal from trial to trial. Perhaps there are some outlier trials (subject was moving or something went wrong?) or perhaps something else. The only way to find out is to visualize the variance instead of the mean. Time for some detective work!