You may have heard the anecdote that when European ships first appeared on the horizon of the New World, the natives could not see them. The argument is that these ships were so unlike anything they had ever seen, so uncategorizable by their brains, that they were rendered invisible. (I’ve heard similar accounts of Western ships appearing on African shores.) You probably thought, “what fools they must’ve been to not be able to see something. They were thoroughly deserving of their centuries of subjugation.”

I was just emptying the dishwasher. I finished, then looked in and noticed that I had not removed a butter tray. The butter tray seldom gets washed and as a result is usually not part of a dishwashing session. In this sense, when placed in the dishwasher, it become something of a foreign object. Was my brain responding to the sight of the dishwasher tray in the same way the brains of native Americans responded to those ships?

Here’s another example that everyone can relate to. I was missing a book. I went into my bedroom to look for it, but even before I entered the room, I was thinking “there’s no way it could be here.” It wasn’t. I searched the rest of the house, then gave the bedroom a second try. There was the book in plain sight, on my desk. Because I had no expectation of finding it there, it had become invisible. Or, it’s possible that the house is haunted by a poltergeist who jokingly removed the book from my view, then returned it to my desk. It seems quite likely that when the next houseguest appears, the poltergeist will use its supernatural abilities to increase the pressure on that person’s head, causing their head to explode and bits of their brain to fly out across the dinner table.