It's not a survey, it's a hard scientific experiment with a test group and a control group. As far as measuring human perception, I don't think a more rigorous test can be done, at least until the day computers can
download, decode, and compare human experience by some quantifiable metric. However, at the rate that the brain is currently being charted along with the rate of growth in computational power and software sophistication, I have to wonder if that day may actually come about in our lifetimes.