So, it may seem like an odd question, but it’s become important for some obscure legal reasons (criteria of university affiliation):
I participated as a test subject volunteer for some psychological experiments at a university. The experiment has long since ended. Am I no longer a university affiliate, or is it a case of “once one, always one?”
You can be affiliated with a university, or some other entity, by engaging with them even if not in the context of a paid appointment, but that does not mean that they own your ass and soul forever just because you did something there once.
Thanks. So…I should not check the box on a form?
If they are asking whether you are currently affiliated (as opposed to: have you ever been affiliated), and you are not currently doing anything there, then I do not see how you could or should check that box, no.
“are” vs. “were”. if it’s over, and they never indicated a later follow-up was part of the work, then you “are” NOT affiliated.
Sounds kind of like a “depends on what the definition of ‘is’ is” scenario.
I’m also wondering about the definition of “affiliated.” Is participating in an experiment as a test subject enough to consider you as “affiliated” with a university?
I probably wouldn’t consider myself as having been “affiliated” with the university if that was my only interaction with the university. I’d think of “affiliates” as employees, students, and people who do business with the university.
But, it likely depends on the exact wording of the question on the OP’s form, and the purpose of it. If it seems like it’s trying to get at whether you ever had any direct interaction with the institution, then it may be safer to say “yes.” But, I agree with other posters – if it’s been years since you had any contact with them, then, no, you aren’t currently affiliated with them.
Specifically, I am wondering about the University of Texas. Its rules state that being a test subject alone doesn’t count (apparently) if you already have a bachelor’s degree or fit some sort of visiting-for-less-than-2-weeks criteria.
But it does have an omnibus “other category for people who need access to UT services or systems.” That seems broad enough that if I merely attend church fellowship meetings regularly on campus (which I do,) that I would be an affiliate.
I’m not sure that I, personally, would classify attending a church meeting in a campus building as qualifying, but if you think it does, I wouldn’t argue the point too strongly.
Ultimately I assume it depends on who the University counts as an affiliate. I didn’t see anything in @Velocity’s link to suggest that someone attending meetings held on campus would automatically qualify as an affiliate, but I did see that “Other” category (“To be used for any individual who does not fit into any other category and needs access to university systems and/or services.”).
Maybe the following circular definition applies: an affiliate is anyone who has access to the university systems and services that are available to anyone affiliated with the university. This might be things like online access to the University’s computer system, or ability to use University facilities like a library or a gym. My WAG, based on the way that “Other” category is worded, is that it’s not a status that anybody automatically has (if they don’t fall into any of the other categories, like being a currently registered student or employee) but that you could be granted that status if you convince them you need it for whatever reason.
If it was explicitly the church that is explicitly associated with the university, maybe - but an outside organization that happens to use the conveniently available space in a university building - I would say no.
Hey, I know this institution pretty well 
Thudlow_Boink has the answer I would give. Participating in a research study would not give you access to any university privileges, aside from being able to be in a lab. I suspect if you are not a student, staff member, alum, faculty member, you are not an affiliate. I would also add contractor or guest of the university (for instance, you were part of a university institute for a week) to the category.
As far as the alumni fund and association are concerned, you’re always connected, even if you’ve gone off the grid for years on Antarctica.
University affiliation is prone to being abused, as in the case of people with slender academic ties (like attending a seminar or holding a loose clinical adjunct position and touting themselves as “Harvard faculty”).
It depends - can you or your children still start fires using mind power?