A tight prior: I believe so strongly that the creation story of Genesis is chronologically and factually correct that no evidence to date embodying physics, biology, chemistry, whatever can possibly sway me from my beliefs. So I'm not even going to study the alternative hypothesis.
And then there's ignorance in combination with tight priors, as in Oklahoma:
Much of the debate about evolution in public schools concerns the content of textbooks. But a new study points to another worrisome trend: teachers who have misconceptions about evolution might be passing those ideas along to their students.
Researchers surveyed Oklahoma high school biology teachers, and found that 23 percent of them misunderstand several key concepts.