Gotcha, thanks! I'm still trying to understand any difference between my data and your data that can cause this inconsistency with my data.

I think the only differences between the data sets are:

• I input blurring options
• I run unpaired t-tests
• All of my data inputs are nifti files in MNI space

I'm having trouble looking into the effect of blurring because when I don't blur with my data, there's no longer significant voxels, and when I try to blur your data, I get an error.

Specifically, with 3 blur options in your data I get the error:

++ 3dXClustSim: AFNI version=AFNI_19.2.09 (Aug  5 2019) [64-bit]
++ Authored by: Lamont Cranston
++ Loading -insdat datasets
*+ WARNING: only 1612 input volumes, less than minimum of 10000
++ Single FPR goal: 9.0%
++ p-value thresholds: 0.0100 0.0090 0.0080 0.0070 0.0060 0.0050 0.0040 0.0030 0.0020 0.0010
++ min cluster size  : 5 voxels
** FATAL ERROR: number of input volumes=1612 not evenly divisible by ncase=3

and with 2 blur options:

++ 3dXClustSim: AFNI version=AFNI_19.2.09 (Aug  5 2019) [64-bit]
++ Authored by: Lamont Cranston
++ Loading -insdat datasets
*+ WARNING: only 1091 input volumes, less than minimum of 10000
++ Single FPR goal: 9.0%
++ p-value thresholds: 0.0100 0.0090 0.0080 0.0070 0.0060 0.0050 0.0040 0.0030 0.0020 0.0010
++ min cluster size  : 5 voxels
** FATAL ERROR: number of input volumes=1091 not evenly divisible by ncase=2

I'm confused by which "volumes" this number is referring to and how to fix it. I'm assuming it means spatial volumes, but I input the mask in your directory that appeared to be a whole brain mask. Any advice you could give would be greatly appreciated! Again, I apologize if this is a basic usage issue.