Asking questions helps!
With the caveat that the whole "individuals conform to group" theory isn't exactly overturned. The study used groups of 4; a single jerk thus makes the group at least 25% jerky - a whopping large percentage of jerkiness. I'd suspect a jerk in a group of 10 would have less impact, 20 even less, and so on.
That said, it's a really thought provoking study.