Scratching when next board

by Peter McOwan, Queen Mary University of London

The next time you are near a blackboard with some chalk you can explore the strange way that our senses interact. Write a few words on the board then rub them out. Now write them again, but this time wear a pair of noise cancelling earplugs: your iPod or phone earplugs will do. You will find that the board feels smoother to write on, because you can't hear the scratching sound. This is an example of a cross modal interaction, what you feel depends on what you hear because of the way our brain combines information from all of the senses to produce your understanding of the world.