Here's a little logic challenge for you.

Each of these cards has a letter on one side and a number on the other. Your task is to prove or disprove the following statement.

"Cards with vowels on always have even numbers on the back".

Most people will pick "A" and "6". The correct answer is "A" and "3".

Turning over "A" is a no-brainer.
Turning over "D" doesn't matter as the statement is about vowels.
Turning over "6" again doesn't matter either. If the letter is a vowel then that's further evidence that sometimes the rule is true. If the letter is a consonant then the rule has not been broken (the statement doesn't exclude consonants from having even numbers on).
Turning over "3" however has the potential to prove the rule wrong. If it's a consonant, no worries, but if it's a vowel then the rule is proved incorrect.

This is a Wason Selection Task. It's another example of the mind's fallibility - it is evidence for a confirmation bias.

When testing hypotheses & assumptions it is very easy to make the mistake of trying to prove them right, when we should be trying to prove them wrong. (So in all likelihood turning over "A" was correct for the wrong reasons. It should have been turned over to try and prove the hypothesis wrong).

This naturally has implications for how we use market research and other elements in our marketing world. It's also why reading blogs, books and anything else you can get hold of is so important - not only to expand one's mind to new ideas but also to find ideas that are discordant with your own. How else can you prove your opinion to be valid if not by failing to prove it wrong?