the similarity of two things is for the person who is doing the measuring to compare them side by side–that is, to experience them side by side. And outside of science fiction, no one can actually have another person’s experience. When we were children, our mothers taught us to call that looking-at-the-mustard-jar experience yellow, and being compliant little learners, we did as we were told. We were pleased when it later turned out that everyone else in the kindergarten claimed to experience yellow when they looked at a mustard jar too. But these shared labels may mask the fact that our actual experiences of yellow are quite different, which is why many people do not discover that they are colour-blind until late in life when an ophthalmologist notices that they do not make the distinctions that others seem to make. So while it seems rather unlikely that human beings have radically different experiences when they look at a mustard jar, when they hear a baby cry, or when they smell a former skunk, it is possible, and if you want to believe it, then you have every right and no one who values her time should try to reason with you.
Remembering Differences
I hope you aren’t giving up that easily. Perhaps the way to determine whether a pair of happinesses actually feel different is to forget about comparing the experiences of different minds and just ask someone who has experienced them both. I may never know if my experience of yellow is different from your experience of yellow, but surely I can tell that my experience of yellow is different from my experience of blue when I mentally compare the two. Right? Unfortunately, this strategy is more complicated than it looks. The nub of the problem is that when we say that we are mentally comparing two of our own subjective experiences, we are not actually having the two experiences at the same time. Rather, we are at best having one of them, having already had the other, and when an interrogator asks us which experience made us happier or whether the two happinesses were the same, we are at best comparing something we are currently experiencing with our memory of something we experienced in the past. This would be unobjectionable were it not for the fact that memories–especially memories of experiences–are notoriously unreliable, a fact that has been demonstrated by both magicians and scientists. First the magic. Look at the six royal cards in figure 4, and pick your favourite. No, don’t tell me. Keep it to yourself. Just look at your card, and say the name once or twice (or write it down) so that you’ll remember it for a few pages.
Fig. 4.
Good. Now consider how scientists have approached the problem of remembered experience. In one study, researchers showed volunteers a colour swatch of the sort one might pick up in the paint aisle of the local hardware store and allowed them to study it for five seconds.21 Some volunteers then spent thirty seconds describing the colour (describers), while other volunteers did not describe it (non-describers). All volunteers were then shown a lineup of six colour swatches, one of which was the colour they had seen thirty seconds earlier, and were asked to pick out the original swatch. The first interesting finding was that only 73 per cent of the non-describers were able to identify it accurately. In other words, fewer than three quarters of these people could tell if this experience of yellow was the same as the experience of yellow they had just a half-minute before. The second interesting finding was that describing the colour impaired rather than improved performance on the identification task. Only 33 per cent of the describers were able accurately to identify the original colour. Apparently, the describers’ verbal descriptions of their experiences ‘overwrote’ their memories of the experiences themselves, and they ended up remembering not what they had experienced but what they had said about what they experienced. And what they had said was not clear and precise enough to help them recognize it when they saw it again thirty seconds later.
Most of us have been in this position. We tell a friend that we were disappointed with the house chardonnay at that trendy downtown bistro, or with the way the string quartet handled our beloved Bartok’s Fourth, but the fact is that we are unlikely to be recalling how the wine actually tasted or how the quartet actually sounded when we make this pronouncement. Rather, we are likely to be recalling that as we left the concert, we mentioned to our companion that both the wine and the music had a promising start and a poor finish. Experiences of chardonnays, string quartets, altruistic deeds and banana-cream pie are rich, complex, multidimensional and impalpable. One of the functions of language is to help us palp them–to help us extract and remember the important features of our experiences so that we can analyse and communicate them later. The New York Times online film archive stores critical synopses of films rather than the films themselves, which would take up far too much space, be far too difficult to search and be thoroughly useless to anyone who wanted to know what a film was like without actually seeing it. Experiences are like movies with several added dimensions, and were our brains to store the full-length feature films of our lives rather than their tidy descriptions, our heads would need to be several times larger. And when we wanted to know or tell others whether the tour of the sculpture garden was worth the price of the ticket, we would have to replay the entire episode to find out. Every act of memory would require precisely the amount of time that the event being remembered had originally taken, which would permanently sideline us the first time someone asked if we liked growing up in Chicago. So we reduce our experiences to words such as happy, which barely do them justice but which are the things we can carry reliably and conveniently with us into the future. The smell of the rose is unresurrectable, but if we know it was good and we know it was sweet, then we know to stop and smell the next one.
Perceiving Differences
Our remembrance of things past is imperfect, thus comparing our new happiness with our memory of our old happiness is a risky way to determine whether two subjective experiences are really different. So let’s try a slightly modified approach. If we cannot remember the feeling of yesterday’s banana-cream pie well enough to compare it with the feeling of today’s good deed, perhaps the solution is to compare experiences that are so close together in time that we can actually watch them change. For instance, if we were to do a version of the colour-swatch experiment in which we reduced the amount of time that passed between the presentation of the original swatch and the presentation of the lineup, surely people would have no problem identifying the original swatch, right? So what if we reduced the time to, say, twenty-five seconds? Or fifteen? Ten? How about a fraction of one And what if, as a bonus, we made the identification task a bit easier by showing volunteers a colour swatch for a few seconds, taking it away for just a fraction of a second, and then showing them one test swatch (instead of a lineup of six) and asking them to tell us whether the single test swatch is the same as the original. No intervening verbal description to confuse their memories, no rival test swatches to confuse their eyes, and only a sliver of a slice of a moment between the presentation of the original and test swatches. 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