Science Experiments

The Nine Dot Challenge!

Fri, 25th Oct 2013

What you Need

Your eyes
This picture on the computer screen.


nine dot puzzle

What to do

1.    Look at the nine dots
2.    Can you join all of them up using a maximum of four continuous straight lines, without taking your imaginary pen off the screen?
3.    You have 9 minutes to get to grips with the answer

What may happen

Don't scroll down unless you want to know the answer.

Want a clue? Think outside the box.








 Nine dot solution

Did you get it?

There are many other different creative ways to solve this. For example, we didnít say how thick the line had to be, it could fill the whole screen and you could join all of the dots up in one go. 

Why does it happen?

Which part of the brain is responsible?

The right side of the prefrontal cortex (the bit of your brain just behind your forehead)

Why is this happening?

Our minds have evolved to solve certain problems effortlessly, yet we struggle to solve others that require us to 'think outside the box'.  

This 9 dot puzzle is an example of thinking creatively. Investigations over the last century show that under laboratory conditions, so being watched by a researcher in a silent room, no one can solve this puzzle!

Why do scientists study this?

Scientists want to know whether you stimulate people to think outside the box and solve puzzles like this by tweaking with the activity of the brain. If they answer this question, they  can learn more about how the brain works.

There are about 100 billion (1011) nerve cells in the brain and about 1000 trillion (1015) connections between them. Thatís a lot! That means in just one small cubic millimetre of human brain tissue there are more than 1 million nerve cells (106) and 1 billion (109) connections. Phew!

To allow us to think and to move, these nerve cells send signals to each other. How is this information encoded?  The answer is that itís encoded by electronic pulses.  So they're very brief, rapid, changes of electrical potential that lasts for 1/1000th of a second, travelling up and down the nerve cells, which are connected to each other.

Recently two Australian neuroscientists Synder and Chi took this information and changed the way people thought, using the power of electricity! They published the study in 2013, in the journal Neuroscience Letters. They took twenty two volunteers and gave them this 9 dot puzzle. How many people could solve this puzzle in 9 minutes? None!

Synder and Chi then split the group and half of people were fitted with something that looked like a shower cap, and attached to the shower cap were electrodes that sent short electrical signals. These carried through the skull, and activated the nerve cells in the right side of the temple, the right prefrontal cortex. This group had ten minutes of electrical stimulation treatment, 2 milliamp current passing across their heads with the positive electrode applied to the right temple and the negative electrode on the left.

Following this treatment, 40% of the subjects then solved the problem. A control group meanwhile, to whom the electrodes were attached but no electrical current applied, were still all unable to solve the problem.  So, they had altered behaviour by electrically stimulating a particular part of the brain.
According to Snyder and Chi, people find this puzzle so difficult because the dominant left temporal lobe uses prior knowledge of shapes to interpret the pattern of dots as a square with imposed rigid boundaries. And as the solution requires drawing lines outside of this shape, subjects think "inside the box" and don't spot it.

The electrical current, however, boosts activity on the more creative right side of the brain and reduces the activity in the creativity-suppressing left side, freeing the subject from their existing cognitive biases and enabling them to see the solution.

Intriguingly, one subject recruited by the researchers but not included in the analysis did immediately solve the puzzle without the benefit of electrical stimulation. But, on further questioning, he revealed having had a head injury as a child that damaged his left temporal lobe.

The researchers say this supports their theory, concluding that brain stimulation has the potential to facilitate those tasks that our minds are not well adapted for.

The Risky Part: what to be aware of and how to keep the science safe:



Risk to Audience

Risk to Presenter

Control Measures

Residual Risk to Audience

Residual Risk to Presenter

9 dot puzzle


None as long as you do not attempt to apply an electric current to your head at home





 More info and references?




Elena Teh

Related Content


Make a comment

the second picture is missing browser, Tue, 11th Feb 2014

a lower key variant of and use for ECT? Brenda, Tue, 29th Apr 2014

See the whole discussion | Make a comment

Not working please enable javascript
Genetics Society