A bat and ball cost $1.10.
The bat costs one dollar more than the ball.
How much does the ball cost?
Simple puzzle, right? Well, more than 50% of students at Ivy League colleges got the wrong answer. At other universities the rate of wrong answers was 80%. The lesson of this simple problem is:
many people are overconfident, prone to place too much faith in their intuitions. They apparently find cognitive effort at least mildly unpleasant and avoid it as much as possible.