30: The more uncertain people are, the more they defend their ideas
The feeling you get when you have two ideas that conflict with each other is called cognative dissonance
To get ride of this dissonance, you either change your belief or deny one of the ideas.
Some takeaways from this information is that when designing keep in mind who your audience is this will influence what ingrained ideas may need to be changed.
Always remember, don't spend a lot of time trying to change someone's ingrained beliefs, instead try to change someone's views by getting them to commit to something small.