Money magazine reported in its January 1997 issue that a group of people were asked which is longer, the Panama Canal or the Suez Canal, and then asked how certain they were that their answer was correct. Among those who were 60% certain, 50% of them got the answer rightmeaning that this group was 10% too sure. But among those who were 90% certain, only 65% got the answer right, meaning that this group was 25% too sure.
Apparently, according to this reported study, the more convinced we are of our knowledge, the bigger the gap between what we actually know and what we think we know. Such overconfidence leads to an illusion of control. As we overestimate the value of our own skills and knowledge, it leads us to make mistakes.
One of the hardest challenges for people is to accept just how little they really know. An example of overestimated knowledge took place a few years ago when a Spanish national lottery winner was asked how he selected the ticket number. He answered that he was positive his lucky number ended in 48because, he said, “I dreamed of the number seven for seven straight nights. And seven times seven is 48.”