Ann Johnson's life recently took a big turn, 18 years after the then teacher suffered a strokeA medical emergency that occurs when the blood supply to a part of the brain is cut off. They can cause lasting brain damage if not treated quickly. which left her unable to move or speak.

Now that has changed. She has become the first person to test a new brain implant which turns her thoughts into speech. Johnson can move her head to type slowly.

Researchers believe it will help people without speech to gain lost parts of their identity.

Brain data is not the same as thought, but these new developments open up the possibility that mind-reading is on its way.

Imagine if you could see other people's thoughts. You could find out what your teacher and friends really think of you.

It could make us all more honest. Everyone would have to be completely open with each other.

It could also be a nightmare: imagine being on a train surrounded by other people's thoughts. It could drive you to madness. We would lose our freedom of thought.

And what if a device fed your thoughts back to the highest bidder? What if a hacker gained control of it? Or if it stored your thoughts up for future use against you?

Would it be great to read people's thoughts?

Yes! We would be able to see people for who they really are, rather than the wall they put up to the world. We could become closer to others than ever before.

No! Thoughts define who we are. If we start listening to other people's thoughts about us it might disrupt our sense of self. It might also be awful to learn what others think of us.

Stroke - A medical emergency that occurs when the blood supply to a part of the brain is cut off. They can cause lasting brain damage if not treated quickly.