SUGGESTED ANSWER TO QUESTION 1-4

We must overcome the confirmation bias in order to test the claim adequately. In other words, we must make sure that we look for evidence that would show the claim to be wrong, in addition to evidence that would show it to be correct. The confirmation bias leads many people to focus on only the "A" and "4" cards: these are the cards with a vowel and an even number, which make up the claim being tested.

The "A" card is important: if we turned it over and found that it had an odd number on the other side, this would disconfirm the claim. If there were an even number on the other side, this would confirm the claim.

The "4" card is of little help, however. Although it is true that it would help to confirm the claim if there were a vowel on the other side, if there were a consonant on the other side, the claim still could be true. This is because the claim does NOT say, if a card has an even number on one side, it has a vowel on the other.

The card that the confirmation bias typically leads people to ignore incorrectly is the "7" card. If we turned it over and found a vowel on the other side, this would disconfirm the claim. Thus, it is an important card to turn over. (A consonant on the other side wouldn't help, however.)

The "D" card cannot help at all. It would not matter what was on the other side because the claim involves vowel cards.

Thus, the confirmation bias causes people to focus on the "A" and "4" cards: we tend to look for evidence that confirms a claim. But this analysis shows that the "7" card is as important as the "A" card (both can disconfirm the claim); and that the "4" card is not very important.