Certain brain cells are activated when you move, and also when you see someone else moving. This means we unconsciously mimic the actions of others and thus share, to some extent, their experience.
These mirror neurons, as they are known, also allow us to know what another person is feeling, without having to think about it.
The discovery of mirror neurons is among the most significant neuroscientific discoveries in recent years.
They mean that when you see someone doing something, in your brain you do it, too – for instance, when you watch a person running, the bit of your brain concerned with planning to move the legs is activated.
And when you see another person expressing an emotion, the areas of your brain associated with feeling that emotion are also activated, making emotions transmittable.
Emotion mirroring is thought to be the basis of empathy. Autistic people often lack empathy and have been found to show less mirror-neuron activity.
Mirror neurons explain why emotion is whipped up in horror film audiences – seeing someone else looking frightened makes you feel scared yourself.