The turtle and the bunny

Let’s start with two short questions:

  1. If a bat and a ball cost together $1.10 and the bat is $1 more expensive than the ball. How much does the ball cost?
  2. If it takes 5 machines 5 minutes to make 5 products, how long will it take 100 machines to make 100 products?

We’ll get back to the answers in a second.

The human brain works like if there would be two systems. Psychologists call them System 1 and System 2. For the sake of simplicity we will refer to them as characters. Let’s call them Agent Fast and Agent Slow.


Agent Slow is the conscious thought, the rational thinker that is capable of following instructions. If you tell him to calculate 9 x 7 he’s the one who will do it. Agent Slow is the lazy one, but capable of catching mistakes.

On the other side, Agent Fast is incredible quick (no surprise). He has to be quick since he is constantly processing tons of information coming trough your senses. He keeps the important bits and throws the rest which is most of it. Fast is working unconsciously, without Slow noticing it. He reads a text even before you want to read it.

Agent Fast is using the long term memory while Agent Slow is using the short memory (work memory), only capable of remembering up to 7 things at a time. This is one of the best findings known in psychology, that the memory is only capable of remembering a low amount of information.

Even so, there are ways to cheat the memory. If for example you will try to remember 7102 it will take at the moment most of your concentration to do so. But if you reverse the numbers as 2017 then you are able to remember them without any effort as they are grouped in something we already know very well.

Another example to illustrate this would be when you first learned how to tie your shoe. It required all your memory and attention to do it. But after doing it a few dozens of times the task was passed to Agent Fast (long-term memory) and became an thoughtless action.

Back to the answers of the questions I’ve written at beginning. I can assume that 80% of you did them wrong.

For the first question if you answered $0.10 you are wrong. Think a little about it. If the ball is $0.10 and the bat is $1 more then the bat is $1.10 and both of them would cost $1.20. The correct answer is $0.5.

The same situation applies for the second question. The answer that comes directly to your mind is 100. But exactly as before it is wrong. 100 machines will create 100 products in 5 minutes.

This is Agent Fast working. Without even being aware, Fast is answering  the question without thinking about it. The task seems to be easy so he assumes that there is no need for his lazy brother.

Don’t get me wrong, I’m not saying that Agent Fast is bad. It is because of him the human species was able to survive thousands of years ago. Even in nowadays it has a critical role in our lives. If he wouldn’t filter the information we receive we would probably go crazy.

What I’m trying to do is to make you more aware of the way our brain works. Very often we don’t put Agent Slow do its job when we take important decisions. It is an effort full process that will take you out of your comfortable area but it will drastically increase the chances you’ll take the right decision.


This article was inspired from the incredible book “Thinking fast and slow” by Daniel Kahneman which I highly recommend it to be read.


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