10 Cent Tweets

What happens when you ask the internet a trick question

"A bat and a ball cost $1.10. The bat costs $1.00 more than the ball. How much does the ball cost?"
System 1
System 2
From Thinking, Fast and Slow
Cognitive Reflection Test

Three simple questions designed to reveal the battle between intuition and reflection in your mind.

Question 1: Bat & Ball

A bat and a ball cost $1.10 in total. The bat costs $1.00 more than the ball. How much does the ball cost?

Intuitive: 10 cents Correct: 5 cents

Question 2: Widgets

If it takes 5 machines 5 minutes to make 5 widgets, how long would it take 100 machines to make 100 widgets?

Intuitive: 100 min Correct: 5 min

Question 3: Lily Pads

A patch of lily pads doubles every day. If it takes 48 days to cover the lake, how long to cover half?

Intuitive: 24 days Correct: 47 days

The wrong answers feel right. That's the point. Your fast, intuitive mind jumps to a conclusion before your slow, analytical mind can intervene.

System 1

Fast, automatic, intuitive. "Obviously 10 cents!"

System 2

Slow, effortful, analytical. "Wait, let me check..."

Based on Shane Frederick's Cognitive Reflection Test (2005). Most people get 0-1 correct on first attempt. The visualization shows what happens when you post the bat & ball question on social media.