Based on the information given, the overconfidence effect is a bias which indicates that the confidence of the teacher is greater than the accuracy of the judgements.
<h3>What is a bias?</h3>
A bias simply means a prejudice against a particular person or group. A mental set simply means the ability of the brain to stick to a particular thing and ignore other alternatives. In this case, the teacher sticked with only what he was told.
The confirmation bias simply means a prejudice against someone. This is unfair towards the person.
