Did you notice that after a light comes on, it takes a little while before you can hit the right button? That’s because when we first see the light, our brain needs to process what is happening before it can send a message to your arm to reach out and hit the correct button. We call this our reaction time. We may not realise it but our brain is doing this constantly: each time we hear our alarm clock ring, smell something delicious cooking or even hear someone cough, our brain has to recognise that signal and respond.