Subliminal

man with the gun. Hats were common in those days, but the gunman had not worn one.

From the nature of these memory errors, and those documented in many other incidents he studied, Munsterberg fashioned a theory of memory. He believed that none of us can retain in memory the vast quantity of details we are confronted with at any moment in our lives and that our memory mistakes have a common origin: they are all artifacts of the techniques our minds employ to fill in the inevitable gaps. Those techniques include relying on our expectations and, more generally, on our belief systems and our prior knowledge. As a result, when our expectations, beliefs, and prior knowledge are at odds with the actual events, our brains can be fooled.

For example, in his own case, Munsterberg had overheard police conversations about the burglar entering through the cellar window and, without realizing it, incorporated that information into his memory of the crime scene. But there was no such evidence, for, as the police later discovered, their initial speculation had been wrong. The burglar had actually entered by removing the lock on the front door. The clock Munsterberg remembered packed in paper for transport had actually been packed in a tablecloth, but, as Munsterberg wrote, his “imagination gradually substituted the usual method of packing with wrapping paper.” As for the candle wax he so clearly remembered having seen on the second floor, it was actually in the attic. When he spotted it, he wasn’t aware of its importance, and by the time the issue came up, he was focused on the strewn papers and other disorder on the second floor, apparently causing him to recall having seen the candle wax there.

Munsterberg published his ideas about memory in a book that became a best seller, On the Witness Stand: Essays on Psychology and Crime.¹¹ In it, he elaborated on a number of key concepts that many researchers now believe correspond to the way memory really does work: first, people have a good memory for the general gist of events but a bad one for the details; second, when pressed for the unremembered details, even well-intentioned people making a sincere effort to be accurate will inadvertently fill in the gaps by making things up; and third, people will believe the memories they make up.

Hugo Munsterberg died on December 17, 1917, at age fifty-three, after suffering a cerebral hemorrhage and collapsing while delivering a lecture to a class at Radcliffe.¹² His ideas on memory, and his pioneering work in applying psychology to law, education, and business, had made him famous, and he’d counted as friends notables like President Theodore Roosevelt and the philosopher Bertrand Russell. But one person Munsterberg did not consider to be a friend in his later years was his onetime sponsor and mentor, William James.¹³ For one, James had become fascinated with psychics, communication with the dead, and other mystical activities, which Munsterberg and many others considered to be pure quackery. For another, James, if not a convert to psychoanalysis, had at least followed Freud’s work with interest and saw value in it. Munsterberg, on the other hand, was blunt about his view of the unconscious, writing, “The story of the subconscious mind can be told in three words: there is none.”¹⁴ In fact, when Freud visited Boston in 1909 to speak—in German—at Harvard, Munsterberg showed his disapproval by remaining conspicuously absent.

Between them, Freud and Munsterberg had come up with theories of mind and memory that were of great importance, but unfortunately the men had little impact on each other: Freud understood much better than Munsterberg did the immense power of the unconscious, but he thought that repression, rather than a dynamic act of creation on the part of the unconscious, was the reason for the gaps and inaccuracies in our memory; while Munsterberg understood much better than Freud did the mechanics and the reasons for memory distortion and loss—but had no sense at all of the unconscious processes that created them.

HOW COULD A memory system that discards so much of our experience have survived the rigors of evolution? Though human memory is subject to the distortion of memory reconstruction, if those subliminal distortions had proved seriously detrimental to our ancestors’ survival, our memory system, or perhaps our species, would not have survived. Though our memory system is far from perfect, it is, in most situations, exactly what evolution requires: it is good enough. In fact, in the big picture, human memory is wonderfully efficient and accurate—sufficient to have enabled our ancestors to generally recognize the creatures they should avoid and those they should hunt down, where the best trout streams are, and the safest way back to camp. In modern terms, the starting point in understanding how memory works is Munsterberg’s realization that the mind is continuously bombarded by a quantity of data so vast that it cannot possibly handle all of it—the roughly eleven million bits per second I mentioned in the last chapter. And so we have traded perfect recall for the ability to handle and process that staggering amount of information.

When we hold a baby’s birthday party in the park, we experience two intense hours of sights and sounds. If we crammed all of them into memory, we’d soon have a huge warehouse of smiles, frosting mustaches, and poopy diapers. Important aspects of the experience would be stored amid irrelevant clutter, such as the patterns of color on each mother’s blouse, the small talk made by each dad, the cries and screams of every child present, and the steadily growing number of ants on the picnic table. The truth is, you don’t care about the ants or the small talk, and you don’t want to remember everything. The challenge that the mind faces, and that the unconscious meets, is to be able to sift through this inventory of data in order to retain the parts that actually do matter to you. If the sifting doesn’t occur, you just get lost in the data dump. You see the trees but not the forest.

There is, in fact, a famous study that illustrates the downside of an unfiltered memory, a case study of an individual who had such a memory. The study was performed over the course of thirty years, starting in the 1920s, by the Russian psychologist A. R. Luria.¹⁵ The man who couldn’t forget was a famed mnemonist named Solomon Shereshevsky. Shereshevsky apparently remembered in great detail everything that happened to him. Once Luria asked Shereshevsky to recount their initial meeting. Shereshevsky recalled that they were in Luria’s apartment and described exactly what the furniture looked like and what Luria was wearing. Then he recited without error the list of seventy words that—fifteen years earlier—Luria had read aloud and asked him to repeat.

The downside of Shereshevsky’s flawless memory was that the details often got in the way of understanding. For instance, Shereshevsky had great trouble recognizing faces. Most of us store in memory the general features of the faces we remember, and when we see someone we know, we identify the person by matching the face we’re looking at to a face in that limited catalog. But Shereshevsky’s memory housed a great many versions of every face he had ever seen. To Shereshevsky, each time a face changed its expression or was seen in different lighting, it was a new face, and he remembered them all. So any given person had not one face but dozens, and when Shereshevsky encountered someone he knew, matching that person’s face to the faces stored in his memory meant performing a search of a vast inventory of images to try to find an exact equivalent to what he was seeing.

Shereshevsky had similar problems with language. If you spoke to him, though he could always play back your exact words, he had trouble understanding your point. The comparison with language is apt, because this is another trees-and-forest problem. Linguists recognize two types of language structure: surface structure and deep structure. Surface structure refers to the specific way an idea is expressed, such as the words used and their order. Deep structure refers to the gist of the idea.¹⁶ Most of us avoid the problems of clutter by retaining the gist but freely discarding details. As a result, although we can retain deep structure—the meaning of what was said—for long periods of time, we can accurately remember surface structure—the words in which it was said—for just eight to ten seconds.¹⁷ Shereshevsky apparently had an exact and long-lasting memory of all the details of the surface structure, but those details interfered with his ability to extract the gist of what was being said. His inability to forget the irrelevant became so frustrating that at times he would write things down on paper and then burn the page, hoping his memory of them would also go up in flames. It didn’t work.

Read the following list of words, and please pay careful attention: candy, sour, sugar, bitter, good, taste, tooth, nice, honey, soda, chocolate, heart, cake, eat, and pie. If you read only the first few words carefully and then skimmed the rest because you lack patience and feel silly allowing yourself to be ordered around by a book, please reconsider—it is important. Please read through the list. Study it for half a minute. Now cover the list so you can’t see the words, and keep it covered while you read the next paragraph.

If you are a Shereshevsky you’ll have no trouble recalling all the words on the list, but chances are, your memory works a bit differently. In fact, I have given the little exercise I am about to give you to a dozen groups over the years, and the result is always the same. I’ll tell you the punch line after I explain the exercise. It is simple: just identify which of the following three words appeared on the above list: taste, point, sweet. Your answer doesn’t have to be just one word. Perhaps all of them were listed? Or none of them? Please give this some thought. Assess each word carefully. Can you picture seeing it on the list? Are you confident? Don’t choose a word