This video has been doing the rounds again. It claims to prove human proclivity for herd behavior, while all it really shows is the urgent need for critical thinking, for understanding of the scientific method, for a sceptical attitude towards any claim, and most of all, for actual facts.

Let’s break it down.

The caption claims this is a social experiment, but we’re shown only a single repetition. An experiment with n=1 is worthless in scientific and statistical terms. A real experiment should at least be repeated multiple times, so that a reliable estimate can be made of the percentage of people who conform to the herd behavior. Since the video presents no data of any kind, this is no more than anecdotal evidence showing that one particular purple-sweatered lady displays herd behavior. (And possibly a rotund man, but we’ll get to that.)

The caption also claims that the video proves something. As argued above, an n=1 experiment can prove nothing at all. It even goes on to claim that “most people” are sheep, but based on the images, we have more reliable data to support the claim that most people are actors.

Which brings me to the next flaw. The video suggests that the purple-sweatered lady actually transfers the herd behavior to new arrivals even after the original actors have departed. (A nice echo of the experiment where apes teach each other a danger long after the apes that have experienced the danger have been removed from the group.) However, there are two major flaws to that suggestion in relation to this so-called experiment.

For one, imitating an individual is something completely different from conforming to herd behavior. After all, the lady isn’t a herd by herself. So the one new arrival who imitates the lady does nothing to prove herd behavior.

For another, as far as I can tell, all the new arrivals before the rotund man seem again to be actors, as evidenced both by their camera-ready make-up and grooming, and by their exaggerated reactions (so they’re not even particularly good actors). If they are actors, they are part of the experimental setup. They are pretending to imitate the lady spontaneously, and thus reinforcing and encouraging the lady’s behavior. From that point onward, the experiment is tainted: the lady’s responses are no longer triggered by the neutral stimulus, but her desired response actively stimulated by the experimental setup. Everything she does after that is useless in terms of experimental results.

And by extension, whatever the rotund man does as a result is also tainted, because the biased affirmation the lady received changes her attitude towards her own behavior and thus biases the stimulus the rotund man receives.

Presenting this video as science actually damages science: it confuses anecdotal evidence with experimental proof, fails to present statistically significant data, and creates insiduous misunderstandings about valid experimental setup.

If anything, this video, and its unchecked spread over social media, is a whole different kind of social experiment: how a lack of critical thinking, scepsis, or familiarity with the scientific method perpetuates an unfounded and far from scientific claim.