From Split Brains to Taxi Drivers: Learning How the Brain Works

The human brain is a wonderfully awkward thing. It lets us write essays, drive cars, remember where we left the keys, and occasionally walk into a room with absolutely no idea why we went there in the first place.

In psychology, one of the most fascinating things is that we have learnt so much about how the brain works not just by looking at healthy brains, but by studying what happens when something changes, gets damaged, or develops in an unusual way. In other words, psychology has often progressed by looking at brains under pressure.

Take the famous split-brain studies by Roger Sperry. These involved people whose two brain hemispheres had been surgically separated to reduce severe epilepsy. Suddenly, psychologists had a way to explore what each half of the brain was doing. What they found was extraordinary. The left and right hemispheres could process information differently, and in some cases seemed almost like two minds sharing the same skull. It was a dramatic reminder that the brain is not just one simple lump doing everything together. It is specialised, divided, and yet somehow usually works as a whole.

Then there is the case of HM, one of the most important patients in psychology. After surgery intended to help his epilepsy, he could no longer form new long-term memories. He could remember much of his earlier life, but new experiences slipped away almost immediately. From this tragic case, psychologists learnt a huge amount about memory. We discovered that memory is not a single system. There are different types of memory, handled by different brain structures, and the hippocampus is especially important for forming new long-term memories.

And then we come to one of my favourites: London taxi drivers. You might think they belong in a transport blog rather than a psychology one, but they helped reveal something very important about the brain. To qualify as a London taxi driver, people traditionally had to learn “The Knowledge” — an astonishing mental map of London streets and routes. Studies found differences in the hippocampus of these taxi drivers compared with other people. In simple terms, the brain appeared to adapt to the demands placed on it. The more it was used for spatial navigation, the more it changed. That is a powerful example of neuroplasticity — the brain’s ability to reorganise itself.

So what do split brains, memory patients, and taxi drivers all have in common?

They show that the brain is both specialised and adaptable.

Some parts of the brain are linked with particular functions. Language tends to be strongly associated with the left hemisphere in most people. Memory formation relies heavily on the hippocampus. Spatial navigation can reshape parts of the brain through repeated use. But at the same time, the brain is not rigid. It changes with experience. It responds to injury, training, learning, and environment.

That matters far beyond the psychology classroom.

It matters for education, because repetition and practice really do help build pathways in the brain.

It matters for rehabilitation, because people can sometimes recover lost skills or find new ways around damaged areas.

It matters for ageing, because keeping the brain active is not just a nice slogan. It has a biological basis.

And it matters for students, because psychology is not just about theories on a page. It is about real people, real brains, and real evidence.

What I like about this topic is that it brings psychology alive. You start with a textbook term like localisation of function or neuroplasticity, and then suddenly you are talking about a man who cannot form new memories, people whose hemispheres no longer communicate normally, or taxi drivers whose brains have adapted to the roads of London.

That is when psychology stops being a list of names and studies and starts becoming a story about what makes us human.

The brain is not a finished machine that comes out of the box complete. It is more like an ongoing building project — part wiring diagram, part road map, part improvisation. Most of the time it works brilliantly. Sometimes it gets things wrong. And sometimes, by studying those mistakes and changes, we learn the most.

So yes, from split brains to taxi drivers, psychology gives us an extraordinary window into how the brain works.

And if you have forgotten where you put your glasses while reading this, do not worry. Your hippocampus is probably doing its best.