Q:

What is the name of the behavior that makes you believe more in something when it contradicts your beliefs? 

What is the name of a common human behavior that makes you believe more in one thing when you are contradicted? 
I read an article a while ago about this behavior saying that people naturally (or instinctively) tend to pay more attention to details that are the opposite beliefs of the ones with which he agrees.  
A good example for that is a fanatic religious person, that the more you try to convince someone that his beliefs are wrong, the more he gets convinced that you are talking bullshit. 
I am pretty sure there is a name for that, does anybody know? 

A:

Confirmation bias

Confirmation bias, also called confirmatory bias or myside bias, is the tendency to search for, interpret, favor, and recall information in a way that confirms one's preexisting beliefs or hypotheses.  It is a type of cognitive bias and a systematic error of inductive reasoning.  People display this bias when they gather or remember information selectively, or when they interpret it in a biased way.  The effect is stronger for emotionally charged issues and for deeply entrenched beliefs.  Confirmation bias is a variation of the more general tendency of apophenia. 

https://en.wikipedia.org/wiki/Confirmation_bias
Attitude polarization

Attitude polarization, also known as belief polarization and polarization effect, is a phenomenon in which a disagreement becomes more extreme as the different parties consider evidence on the issue.  It is one of the effects of confirmation bias: the tendency of people to search for and interpret evidence selectively, to reinforce their current beliefs or attitudes.  When people encounter ambiguous evidence, this bias can potentially result in each of them interpreting it as in support of their existing attitudes, widening rather than narrowing the disagreement between them. 

https://en.wikipedia.org/wiki/Group_polarization#Attitude_polarization

A:

Stubbornness and recalcitrance are commonly used to describe this sort of behaviour. 
Other words include obstinate, unyielding, intransigent, intractable, mulish, pigheaded. 
Personally I quite like refractory, but its use in this sense is uncommon, so I don't think it's necessarily a good answer here. 

A:

if you're looking for ONE WORD - try reactance:

Reactance is an emotional reaction in
  direct contradiction to rules or
  regulations that threaten or eliminate
  specific behavioral freedoms. 
Reactance can occur when someone is
  heavily pressured to accept a certain
  view or attitude.  Reactance can
  cause the person to adopt or
  strengthen a view or attitude that is
  contrary to what was intended, and also increases resistance to
  persuasion.  People using reverse
  psychology are playing on at least an
  informal awareness of reactance,
  attempting to influence someone to
  choose the opposite of what they
  request.