Photo of Bluebell Woods in Sussex Photo of Bluebell Woods in Sussex

Fast Recognition and Optical Illusions in Nature

Our brains are pattern-recognising machines. This is true everywhere, but not least in nature, where it honed these skills over millions of years.

Bird calls, tree shapes, wildflower colours, animal movement… There are so many ways our senses can feed a simple pattern to our brain, which then gives us a lightning fast clue as to what is going on around us and what will likely happen next.

In the book, Wild Signs and Star Paths, I explored the extraordinary way our brain has evolved to quickly make sense of any natural environment. The clues it uses to trigger this sense I labelled ‘Keys’.

We can predict the next movements of animals from the twitch in their ears. Or the arrival of another person by a change in birdsong. Or a weather change from the way a tree sounds different. There are hundreds of examples, but in the book I focus on the 52 keys that I find most effective. (They are listed on the Contents page.)

The psychological science behind these phenomena has been well explored by Daniel Kahneman and others. Kahneman’s work focuses more on economics and urban lifestyles, but it was very helpful when I came to research why certain natural clues and signs worked and also why they sometimes don’t.

Psychologists describe the brain as having two systems: ‘fast’ and ‘slow’ thinking. Fast thinking is necessary in any survival situation. Slow thinking is needed for calculation, measurement or weighing options.

Amazing, But Not Perfect

The brain’s ability to spot patterns is like a super-power, but the evolutionary need for speed in nature can lead to mistakes. There are times when our brain is in a hurry and slips on the ice.

This morning the sky’s light bounced off my watch, which then reflected back off the window into the corner of my eye. My brain told me that there was a white butterfly outside the window. I have tried to capture the effect in the image above.

The size, colour and flickering motion led to my brain trying to match a pattern to a context. What is white, about an inch long and flutters outside windows? Slow thinking might give us a longer list. But my brain used fast thinking to tell me that there was a butterfly there, in fractions of a second.

It was wrong on this occasion, but in evolutionary terms it was a ‘good’ mistake. No harm was done. If the pattern had told me that there was a dangerous predator there, it could have saved my life. Unlikely in West Sussex, but you get the idea.

Another example is the way evolution has hard-wired us to take note of certain shapes. Even someone who has lived their whole life in an inner city will stop and take care whenever they see this shape in the grass:

It takes a few seconds to make sure that it is just a stick. That is the switch from fast to slow thinking.