Admitting to a lack of knowledge
In some cultures, saving face, or keeping up a good outward image, is very important, regardless of what may actually be the state of affairs inwardly or privately.
In English-speaking areas, and especially in North America, it is sincerity that takes precedence. If a person is asked something for which he does not know the answer, he feels perfectly free to admit that he does not know. He may say: "I'm sorry, I do not know" 0r "You're got me on that one."