I did it as part of another paid study with the Feds. It's all anonymized and you sign paperwork stating as much. Nothing can be used against you, even if you completely fail. If you want to quit halfway through the study, you get paid for it still. It's with the CAMI research people.
I found it interesting and they will give you your results on how you compare with the study group and with other study groups. All in it took around 2 hours. The purpose of the study is to update their cog screening tests, which haven't changed in decades. They need a baseline of pilots holding various qualifications and medical certificates.
They are all about the data. Your name won't go any further than the study room.