An influential theory among psychologists is that we’re cognitive misers. This is the idea that we are reluctant to do mental work unless we have to, we try to avoid thinking things though fully when a short cut is available. […] The theory explains why we’d much rather type a zipcode into a sat-nav device or Google Maps than memorise and recall the location of a venue – it’s so much easier to do so.

Research shows that people don’t tend to rely on their memories for things they can easily access. Things like the world in front of our eyes, for example, can be changed quite radically without people noticing. Experiments have shown that buildings can somehow disappear from pictures we’re looking at, or the people we’re talking to can be switched with someone else, and often we won’t notice – a phenomenon called “change blindness”. This isn’t as an example of human stupidity – far from it, in fact – this is an example of mental efficiency. The mind relies on the world as a better record than memory, and usually that’s a good assumption.

As a result, philosophers have suggested that the mind is designed to spread itself out over the environment. So much so that, they suggest, the thinking is really happening in the environment as much as it is happening in our brains. The philosopher Andy Clark called humans “natural born cyborgs“, beings with minds that naturally incorporate new tools, ideas and abilities. From Clark’s perspective, the route to a solution is not the issue – having the right tools really does mean you know the answers, just as much as already knowing the answer.

So as well as having a physical environment – like the rooms or buildings we live or work in – we also have a mental environment. Which means that when I ask you where your mind is, you shouldn’t point toward the centre of your forehead. As research on areas like transactive memory shows, our minds are made up just as much by the people and tools around us as they are by the brain cells inside our skull.