Related to hindsight bias is overconfidence: our tendency to overestimate our ability to make correct predictions. Across a wide variety of tasks, most of us are more confident in our predictive abilities than we should be (Hoffrage, 2004; Smith & Dumont, 2002).
Try the following ten questions. Few people know any of the answers exactly, but you need only an approximation. For each, give a range within which you are 90% sure the correct answer lies. For example, consider this question: In the 2000 summer Olympics, how many silver medals did China win?
You might decide that you would be surprised if they won fewer than 5 or more than 25, so you guess “5 to 25.” If so, you would be right, because China won 16 silver medals. Okay, that’s the idea. Now fill in your answers: Your estimate (as a 90% confidence range)
1. How old was Martin Luther King Jr. at the time of his death? __ to __
2. How long is the Nile River? __ to __
3. How many countries belong to OPEC? __ to __
4. How many books are in the Old Testament? __ to __
5. What is the diameter of the moon? __ to __
6. What is the weight of an empty Boeing 747? __ to __
7. In what year was Mozart born? __ to __
8. What is the gestation period of an Asian elephant? (in days) __ to __
9. How far is London from Tokyo? __ to __
10. What is the deepest known point in the ocean? (in feet/ meters) __ to __
Now check your answers on end (Plous, 1993). How many of your ranges included the correct answer? Because you said you were 90% confident of each answer, you should be right on about nine of the ten. However, most people miss more than half.
That is, they were overconfident; they believed their estimates were more accurate than they actually were. These were, of course, difficult questions. On easy questions, the trend is reversed and people tend to be underconfident (Erev, Wallsten, & Budescu, 1994; Juslin, Winman, & Olsson, 2000). You can try additional items with the Online Try It Yourself exercise Overconfidence.
Philip Tetlock (1994) studied government officials and consultants, foreign policy professors, newspaper columnists, and others who make their living by analyzing and predicting world events. He asked them to predict world events over the next several years—such as what would happen in Korea, the Middle East, Eastern Europe, and Cuba—and to state their confidence in their predictions (e.g., 70%).
Five years later, he compared predictions to actual results and found very low accuracy, especially among those who were the most confident and those with a strong liberal or conservative point of view. That is, those who saw both sides of a question were more likely to be right.
Most people are overconfident of how well they understand complex physical processes. In one study college students rated how well they understood how various devices work, including a speedometer, zipper, flush toilet, cylinder lock, helicopter, quartz watch, and a sewing machine.
Then the researchers asked them to explain four of the devices and answer questions, such as “How could someone pick a cylinder lock?” and “How does a helicopter go from hovering to forward flight?” After producing what were obviously weak answers, nearly all students lowered their ratings of understanding for these four devices (Rozenblit & Keil, 2002). However, curiously, some insisted that except for the devices that the experimenters happened to choose, they understood the other ones well!
(1) 39 years. (2) 4,187 miles, or 6,738 kilometers. (3) 13 countries. (4) 39 books. (5) 2,160 miles, or 3,476 kilometers. (6) 390,000 pounds, or 177,000 kilograms. (7) 1756. (8) 645 days. (9) 5,959 miles, or 9,590 kilometers. (10) 36,198 feet, or 11,033 meters.
Kalat, James W.Introduction to Psychology.Wadsworth Publishing; 8 edition (April 12, 2007)
Overconfidence effect https://en.wikipedia.org/wiki/Overconfidence_effect