Three’s the Magic Number…But Why?

The number three consistently pops up both in ancient and modern history – from literature (such as Shakespeare’s Three Weird Sisters in Macbeth), to religion (The Holy Trinity), to mathematics (Pythagorean Triads), and is considered a sacred number in many cultures. But have you ever wondered why three is the ‘Magic Number’? If you have, great! If you haven’t, you are now!

There are many arguments as to why three is the magic number – however, an interesting, albeit less explored avenue, is to do with neuroscience. 

Our brains are phenomenal at identifying and recognising patterns, and are constantly trying to convert ambient stimuli into lower energy and memorable patterns. In contrast, the human brain is notoriously bad at memorising facts and information that cannot be processed as a pattern – this is one of the many reasons we can remember songs from a decade ago with sometimes worrying clarity. 

Our ventromedial prefrontal cortex, the area of the brain responsible for pattern recognition, is the same area associated with reward. By converting information into a pattern, not only are we more likely to remember it, but additionally we can feel a sense of reward from it.

But what has any of this got to do with the number three? Three is a unique number; it is one of the first prime numbers, and is the sum of the special numbers one and two – making a triad (there’s our magic number three again!) of special numbers – one, two and three. Given our brain is inherently inclined to convert stimuli into patterns, the number three is so prominent because it is the smallest number that can be converted into a pattern. 

On top of this, the average person can remember 4-9 things 50% of the time, which isn’t very helpful. Three, on the other hand, is much easier to remember for most people (out of 10,000, fewer than two people won’t be able to remember three things) – thus, not only does our brain start pattern recognition and processing at the number three, we’re much more likely to remember three things at a time. This is one of the reasons why so many marketing strategies promote the ‘rule of threes’ in advertisement. 

Another reason three, and other smaller ‘magic numbers’ such as seven, can be considered magic numbers is because of our right superior parietal lobe, at the upper back of the brain. 

It of the brain is associated with numerosity – i.e. how we quantify. This section maps out numbers, and is much more selective around lower numbers – in other words, we can better quantify smaller numbers than larger ones, and thus can better recognise things that come in threes. For example, it’s much easier to estimate there are two dogs in a park than 30. Interestingly enough, this section of the brain doesn’t respond to digits – so you don’t have to be a maths whiz to be great at estimating quantities.

It’s important to remember that lots of research on the brain is still in its early stages, but what can be concluded is that the brain is a weird, complex, and fascinating organ, and that when it comes to the brain, three’s definitely a charm! 

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