Please may I ask a follow-up to my original question?
Having done the analyses, inputting a binarised mask into the "Pre-threshold masking" option in the Post-stats tab, I now have my results. I'm a little confused because I get results in voxels (in the caudate) that are outside of the mask I used as a pre-threshold mask. I'm not sure how to interpret this as I thought using the pre-threshold mask would only yield results within the mask?
Thank you in advance for your insights.