Gosh. Given how simple we’ve made the task, shouldn’t we predict that everyone will pass it with, um, flying colours?
Yes, but only if we enjoy being wrong. In a study conceptually similar to the one we just designed, researchers asked volunteers to look at a computer screen and read some odd-looking text.22 What made the text so odd was that it alternated between uppercase and lowercase, so that it lOoKeD lIkE tHiS. Now, as you may know, when people seem to be staring directly at something, their eyes are actually flickering slightly away from the thing they are staring at three or four times per second, which is why eyeballs look jiggly if you study them up close. The researchers used an eye-tracking device that tells a computer when the volunteer’s eyes are fixated on the object on the screen and when they have briefly jiggled away. Whenever the volunteers’ eyeballs jiggled away from the text for a fraction of a second, the computer played a trick on them: it changed the case of every letter in the text they were reading so that the text that lOoKeD lIkE tHiS suddenly LoOkEd LiKe ThIs. Amazingly, volunteers did not notice that the text was alternating between different styles several times each second as they read it. Subsequent research has shown that people fail to notice a wide range of these ‘visual discontinuities’, which is why filmmakers can suddenly change the style of a woman’s dress or the colour of a man’s hair from one cut to the next, or cause an item on a table to disappear entirely, all without ever waking the audience.23 Interestingly, when people are asked to predict whether they would notice such visual discontinuities, they are quite confident that they would.24
And it isn’t just the subtle changes we miss. Even dramatic changes to the appearance of a scene are sometimes overlooked. In an experiment taken straight from the pages of Candid Camera, researchers arranged for a researcher to approach pedestrians on a college campus and ask for directions to a particular building.25 While the pedestrian and the researcher conferred over the researcher’s map, two construction workers, each holding one end of a large door, rudely cut between them, temporarily obstructing the pedestrian’s view of the researcher. As the construction workers passed, the original researcher crouched down behind the door and walked off with the construction workers, while a new researcher, who had been hiding behind the door all along, took his place and picked up the conversation. The original and substitute researchers were of different heights and builds and had noticeably different voices, haircuts and clothing. You would have no trouble telling them apart if they were standing side by side. So what did the Good Samaritans who had stopped to help a lost tourist make of this switcheroo? Not much. In fact, most of the pedestrians failed to notice–failed to notice that the person to whom they were talking had suddenly been transformed into an entirely new individual.
Are we to believe, then, that people cannot tell when their experience of the world has changed right before their eyes? Of course not. If we take this research to its logical extreme we end up as extremists generally do: mired in absurdity and handing out pamphlets. If we could never tell when our experience of the world had changed, how could we know that something was moving, how could we tell whether to stop or go at an intersection, and how could we count beyond one? These experiments tell us that the experiences of our former selves are sometimes as opaque to us as the experiences of other people, but more important, they tell us when this is most and least likely to be the case. What was the critical ingredient that allowed each of the foregoing studies to produce the results it did? In each instance, volunteers were not attending to their own experience of a particular aspect of a stimulus at the moment of its transition. In the colour-swatch study, the swatches were swapped in another room during the thirty-second break; in the reading study, the text was changed when the volunteer’s eye had momentarily jiggled away; in the door study, the researchers switched places only when a large piece of wood was obstructing the volunteer’s view. We would not expect these studies to show the same results if burnt umber became fluorescent mauve, or if this became t h a t, or if an accountant from Poughkeepsie became Queen Elizabeth II while the volunteer was looking right at her, or him, or whatever. And indeed, research has shown that when volunteers are paying close attention to a stimulus at the precise moment that it changes, they do notice that change quickly and reliably.26 The point of these studies is not that we are hopelessly inept at detecting changes in our experience of the world but rather that unless our minds are keenly focused on a particular aspect of that experience at the very moment it changes, we will be forced to rely on our memories–forced to compare our current experience to our recollection of our former experience–in order to detect the change.
Magicians have known all this for centuries, of course, and have traditionally used their knowledge to spare the rest of us the undue burden of money. A few pages back you chose a card from a group of six. What I didn’t tell you at the time was that I have powers far beyond those of mortal men, and therefore I knew which card you were going to pick before you picked it. To prove it, I have removed your card from the group. Take a look at figure 5 and tell me I’m not amazing. How did I do it? This trick is much more exciting, of course, when you don’t know beforehand that it’s a trick and you don’t have to wade through several pages of text to hear the punchline. And it doesn’t work at all if you compare the two figures side by side, because you instantly see that none of the cards in figure 4 (including the one you picked) appears in figure 5. But when there is some possibility that the magician knows your chosen card–either by sleight of hand, shrewd deduction or telepathy–and when your jiggly eyes are not looking directly at the first group of six as it transforms into the second group of five, the illusion can be quite powerful. Indeed, when the trick first appeared on a website, some of the smartest scientists I know hypothesized that a newfangled technology was allowing the server to guess their card by tracking the speed and acceleration of their keystrokes. I personally removed my hand from the mouse just to make sure that its subtle movements were not being measured. It did not occur to me until the third time through that while I had seen the first group of six cards, I had only remembered my verbal label for the card I had chosen, and hence had failed to notice that all the other cards had changed as well.27 What’s important to note for our purposes is that card tricks like this work for precisely the same reason that people find it difficult to say how happy they were in their previous marriages.
Fig. 5
Happy Talk
Reba and Lori Schappell claim to be happy, and that disturbs us. We are rock-solid certain that it just can’t be true, and yet, it looks as though there is no foolproof method for comparing their happiness with our own. If they say they are happy, then on what basis can we conclude that they are wrong? Well, we might try the more lawyerly tactic of questioning their ability to know, evaluate or describe their own experience. ‘They may think they’re happy’, we could say, ‘but that’s only because they don’t know what happiness really is.’ In other words, because Lori and Reba have never had many of the experiences that we singletons have had–spinning cartwheels in a meadow, snorkeling along the Great Barrier Reef, strolling down the avenue without drawing a crowd–we suspect they may have an impoverished background of happy experiences that leads them to evaluate their lives differently than the rest of us would. If, for instance, we were to give the twins a birthday cake, hand them an eight-point rating scale (which can be thought of as an artificial language with eight words for different intensities of happiness), and ask them to report on their subjective experience, they might tell us they felt a joyful eight. But isn’t it likely that their eight and our eight represent fundamentally different levels of joy, and that their use of the eight-word language is distorted by their unenviable situation, which has never allowed them to discover how happy a person can really be? Lori and Reba may be using the eight-word language differently than we do because for them, birthday cake is as good as it gets. They label their happiest experience with the happiest word in the eight-word language, naturally, but this should not cause
