It is a cognitive bias in which people might wrongfully underestimate or overestimate their knowledge and ability in a particular activity.
A study conducted by Cornell University psychologists proves this concept. They tested a group of participants on their logic, sense of humour, grammar, and found that people who performed bad had rated their skills to be above average. For example, who scored in the 10th percentile and rated themselves to be in the 56th percentile.
They found that the problem was in their metacognition, i.e., their ability to analyse their own thoughts and performance. This happens because people want to look smart rather than looking dumb and unskilled in that activity. This bias is observed in most people who a weak point in a certain activity or skill where this bias can occur.
This also results in something known as double curse. As people not only perform poorly but also judge themselves poorly which enables them from growing and learning.
People think that they know more than they actually do because of overconfidence. A type of overconfidence is called over precision which occurs when a person exaggerates knowing the answer. Another type which leads to this bias is called overestimation in which people overestimate their perception of their skills to their actual skills.
People can avoid this effect by challenging and questioning themselves on how much they actually know about a topic.
Paawni Goyal 