Here’s a puzzle: If U.S. students do so badly on international tests, especially in math, how can it be that the U.S. economy is so strong? An educated workforce is supposedly a big predictor of a country’s income and annual growth. Yet the performance of American 15-year-olds on the Program for International Student Assessment, or PISA, has always been lackluster. Since 2012, U.S. math scores have slumped down into the bottom half. Meanwhile, the U.S. remains the top economy in the world this year with over $19 trillion of goods and services produced. No other country even comes close.
A group of behavioral economists wondered if U.S. students are actually not as incompetent as their scores would suggest, but simply lazy when they’re taking the PISA exam. To test this, they created a PISA-like exam of just 25 questions and asked 447 sophomores at two different high schools to take it. Seconds before the test started, they surprised half the students at each school with an envelope of 25 $1 bills. The researchers told those students they would take away one dollar for each incorrect or unanswered question.