Thanks for the reply, Ollie -- I have just been gearing up for the thesis but this volunteer thing really seems like the better match. I could conceivably ramrod some crazy people into someone's cognitive lab, but that would take a lot of spin, whereas the volunteer lab is already into the crazy people. I just didn't want to abandon an "official" thesis if it was considered to be a crucial component of undergrad prep (since my original undergrad prep was pretty lame!)