Right, I think there is more than the basic "I will agree what the scientist says" going on in something like this. For instance, in an experiment like this, especially in a country known for ethical experimenting, it would be a pretty reasonable assumption that the people in charge of the experiment have figured out the risks involved and will shoulder the responsibility if anything goes wrong.
Basically, I wouldn't be surprised to hear that many people in an experiment like this were assuming that the scientist was correct in saying there wouldn't be any permanent damage, and that even if they (the experiment subject) thought it was dangerous, the scientist probably had better judgment and more understanding of the situation. I'm not sure if I remember this correctly (so don't quote me on this), but I think that someone did an experiment where instead of a scientist it was some random guy urging the subject on, and the number of people who went all the way decreased drastically.