That sounds like the lead-in to some sick joke at a comedy club, but it's a serious question.
In 1975, psychologist C. Daniel Batson published a report about an experiment he conducted as part of a debate between psychologists regarding "dissonance theory" which he explains by quoting a 1956 paper by other researchers:
Man's resourcefulness goes beyond simply protecting a belief. Suppose an individual believes something with his whole heart, suppose further that he has a commitment to this belief and that he has taken irrevocable actions because of it, finally, suppose that he is presented with evidence, unequivocal and undeniable evidence, that his belief is wrong: what will happen? The individual will frequently emerge, not only unshaken, but even more convinced of the truth of his beliefs than ever before. Indeed, he may even show new fervor for convincing and converting other people to his view.Batson says: "If the process described here actually occurs, it can hardly be called rational information processing or dispassionate self-perception. Rather, it implies rationalization, an active self-justifying intensification of belief, presumably in an attempt to defend oneself against the implications of disconfirming information."
To test this idea, Batson provided 50 female high school students active in the youth program of a Presbyterian church in central New Jersey very strong (contrived) evidence that seemed to disprove the divinity of Jesus.
Batson found that the students with the strongest belief were the least affected by the evidence. Moreover, the evidence that their belief was wrong actually strengthened their belief. He summarized:
... the present findings seem to have important practical implications. It has been said, "You will know the Truth and the Truth will make you free [John 8:32]." The present research seems to question this assertion. The more one publicly proclaims one's conviction about personally significant truths, the more one seems bound to these truths. One is less free to modify one's position, to take account of new, discrepant information. But perhaps this is not what is meant by freedom in the above statement. If it means that one will be free from the rational process of taking account of all relevant information in the formulation of one's beliefs, than the present research seems clearly supportive.This and similar findings about people's opinions controlling their ability to think rationally helps explain why vivisectors refuse to believe the careful observations made by so many people that what they are doing isn't good science, isn't productive, is cruel, is poorly regulated, and is wasteful of public funds. [See: http://www.animalexperiments.info/studies.html for a few examples.] It explains why solid evidence that what they are doing isn't helpful continues to be denied by them and why some of the most ardent continue to troll the Internet desperately defending their ilk and industry whenever any problem is publicized. When it comes to accommodating facts that prove them wrong about their cherished beliefs, they are no more rational than teenage Presbyterian girls challenged with facts questioning the divinity of Jesus.
In attempting to force a firmly committed believer to "face up to the facts," one may be damned if he does and damned if he doesn't. If, on the one hand, the believer does not accept the facts as facts, then clearly one's arguments are without impact. But, on the other hand, if the believer accepts them as true, this may actually drive him into even more fervent adherence to his initial position.[Rational processing or rationalization? The effect of disconfirming information on a stated religious belief. Journal of Personality and Social Psychology. 1975.]
In all fairness to the vivisectors, I too may suffer from this problem. After all, I regularly proclaim my convictions about my personally significant beliefs about animals, so maybe I am less free to modify my position, to take account of new, discrepant information. But then, even vivisectors are now admitting that animals have thoughts, feelings, desires, and preferences -- the reasons for my beliefs. If someone could prove that cows don't have any feelings, I'd eat them.
The difference I see between our positions seems to suggests a much more self-protective rationalization on their part. They are terrified at the thought of subjecting their world to public inspection and consideration. You may remember that we worked at some length and effort to have the local county government sanction a citizens' advisory panel to examine the University of Wisconsin-Madison's use of monkeys in its labs. This idea was hair-raising to the vivisectors. They turned out in force and lied and misled and did everything in their power to stop the county from actually looking at what they are doing. This is not the behavior of people who are confident about themselves, their work, or their institution, so maybe, in this respect, they aren't as honorable as the young girls who simply believed.