Apparently you just can’t change anti-vaxxers’ minds.
This reaction, where people become more assured of their stupid opinions when confronted with factual or scientific evidence proving them wrong, has been demonstrated in similar studies time and time again. (This is why arguing with your Facebook friends who watch Fox News will only bring you migraines.)
What is the definition of a rational mind? It seems to be that this kind of behavior certainly describes an irrational mind. How does this happen? Again, the psychological biases described by McRaney and others reveals some of it: mostly they cannot bear to think that they are wrong about something so fundamental, because that realization would undermine their sense of self-worth and throw into doubt everything else they think they are certain about; and their support of this thinking in a community of like-thinkers bolsters their commitment to in-group thinking vs the thinking of ‘others’. Bubbles.