"Humans have a hardwired process of attention and awareness that is hackable. When people focus on one thing, their brains automatically suppress everything that happens around it. Magicians have devised many techniques that exploit this 'tunnel vision.'
People can pay attention in various ways. Magicians exploit 'top-down,' or deliberate, attention by, say, asking a person to scan a book. They capture 'bottom-up' attention with distracting displays such as doves fluttering out of a hat."