We can’t trust our memories, and we can’t always trust our senses, either. The Tardis, the Doctor's multipurpose time machine, generates what is known as a perception filter, so people passing by simply assimilate it into their surroundings without worrying about it. In one episode, a perception filter cloaks a house’s entire second floor; in another, it hides the room in which an escaped mass murder (and an alien one, at that) has hidden for about a decade.
But what the show is calling a perception filter is just an extreme version of one of our biggest cognitive problems: We can’t notice everything. Magic tricks are infamous for taking advantage of that human weakness. Most illusionist magic works by misdirection, steering our attention away from the less-than-magical mechanics supporting the trick.
For example, pickpocket magician Apollo Robbins swipes a participant’s possessions – hat, glasses, wallet – just by engaging them in a conversation that keeps their attention away from his pilfering hands. As he told the New Yorker, “It’s all about the choreography of people’s attention. Attention is like water. It flows. It’s liquid. You create channels to divert it, and you hope that it flows the right way.”
