sensory integration
Rule #9
Stimulate more of the senses.
EVERY TIME TIM SEES the letter “E,” he also sees the color red. He describes the color change as if suddenly forced to look at the world through red-tinted glasses. When
Tim looks away from the letter “E,” his world returns to normal, until he encounters the letter “O.” Then the world turns blue. For Tim, reading a book is like living in a disco. For a long time, Tim thought this happened to everyone. When he discovered this happened to no one—at least not in his immediate circle—he began to suspect he was crazy. Neither impression was correct, of course. Tim is suffering—if that’s the right word—from a brain condition called synesthesia. Though experienced by as many as 1 in 2,000 people (some think 1 in 200), it is a behavior about which scientists know next to nothing. At first blush, there appears to be a short-circuiting between the processing of various sensory inputs. If scientists can nail down what happens when sensory processing goes wrong, they may gain more understanding about what happens when it goes right. So, synesthesia intrigues scientists interested in how the brain processes the world’s many senses. The effect that this has on learning forms the heart of our Brain Rule: Stimulate more of the senses at the same time.
saturday night fever
That you can detect anything has always seemed like a minor miracle to me. On one hand, the inside of your head is a darkened, silent place, lonely as a cave. On the other hand, your head crackles with the perceptions of the whole world, sight, sound, taste, smell, touch, energetic as a frat party. How could this be? For a long time, nobody could figure it out. The Greeks didn’t think the brain did much of anything. It just sat there like an inert pile of clay (indeed, it does not generate enough electricity to prick your finger). Aristotle thought the heart held all the action, pumping out rich, red blood 24 hours a day. The heart, he reasoned, harbored the “vital flame of life,” a fire producing enough heat to give the brain a job description: to act as a cooling device (he thought the lungs helped out, too). Perhaps taking a cue from our Macedonian mentor, we still use the word “heart to describe many aspects of mental life.
How does the brain, brooding in its isolated bony chambers, perceive the world? Consider this example: It is Friday night at a New York club. The dance beat dominates, both annoying and hypnotic, felt more than heard. Laser lights shoot across the room. Bodies move. The smells of alcohol, fried food, and illegal smoking mix in the atmosphere like a second sound track. In the corner, a jilted lover is crying. There is so much information in the room, you are beginning to get a headache, so you step out for a breath of fresh air. The jilted lover follows you.
Snapshots like these illustrate the incredible amount of sensory information your brain must process simultaneously. External physical inputs and internal emotional inputs all are presented to your brain in a never-ending fire hose of sensations. Dance clubs may seem the extreme. Yet there may be no more information there than what you’d normally experience the next morning on the streets of Manhattan. Faithfully, your brain perceives the screech of the taxis, the pretzels for sale, the crosswalk signal, and the people brushing past, just as it could hear the pounding beat and smell the cigarettes last night. You are a wonder. And we in brain-science land are only beginning to figure out how you do it.
Scientists often point to an experience called the McGurk effect to illustrate sensory integration. Suppose researchers showed you a video of a person saying the surprisingly ugly syllable “ga.” Unbeknownst to you, the scientists had turned off the sound of the original video and had dubbed the sound “ba” onto it. When the scientist asks you to listen to the video with your eyes closed, you hear “ba” just fine. But if you open your eyes, your brain suddenly encounters the shape of the lips saying “ga” while your ears are still hearing “ba.” The brain has no idea what to do with this contradiction. So it makes something up. If you are like most people, what you actually will hear when your eyes open is the syllable “da.” This is the brain’s compromise between what you hear and what you see—its need to attempt integration.
But you don’t have to be in a laboratory to show this. You can just go to a movie. The actors you see speaking to each other on screen are not really speaking to each other at all. Their voices emanate from speakers cleverly placed around the room: some behind you, some beside you; none centered on the actorsmouths. Even so, you believe the voices are coming from those mouths. Your eye observes lips moving in tandem with the words your ears are hearing, and the brain combines the experience to trick you into believing the dialogue comes from the screen. Together, these senses create the perception of someone speaking in front of you, when actually nobody is speaking in front of you.
how the senses integrate
Analyses like these have led scientists to propose a series of theories about how the senses integrate. On one end of this large continuum are ideas that remind me of the British armies during the Revolutionary War. On the other end are ideas that remind me of how the Americans fought them. The British, steeped in the traditions of large European land wars, had lots of central planning. The field office gathered information from leaders on the battleground and then issued its commands. The Americans, steeped in the traditions of nothing, used guerrilla tactics: on-the-ground analysis and decision making prior to consultation with a central command.
Take the sound of a single gunshot over a green field during that war. In the British model of this experience, our senses function separately, sending their information into the brain’s central command, its sophisticated perception centers. Only in these centers does the brain combine the sensory inputs into a cohesive perception of the environment. The ears hear the rifle and generate a complete auditory report of what just occurred. The eyes see the smoke from the gun arising from the turf and process the information separately, generating a visual report of the event. The nose, smelling gunpowder, does the same thing. They each send their data to central command. There, the inputs are bound together, a cohesive perception is created, and the brain lets the soldier in on what he just experienced. The processes can be divided into three steps:
STEP 1: SENSATION
This is where we capture the energies from our environment pushing themselves into our orifices and rubbing against our skin. The effort involves converting this external information into a brain-friendly electrical language.
STEP 2: ROUTING
Once the information is successfully translated into head-speak, it is sent off to appropriate regions of the brain for further processing. The signals for vision, hearing, touch, taste and smell all have separate, specialized places where this processing occurs. A region called the thalamus, that well-connected, egg-shaped structure in the middle of your “second brain,” helps supervise most of this shuttling.
STEP 3: PERCEPTION
The various senses start merging their information. These integrated signals are sent to increasingly complex areas of the brain (actually called higher regions), and we begin to perceive what our senses have given us. As we shall see shortly, this final step has both bottom-up and top-down features.
The American model puts things very differently. Here the senses work together from the very beginning, consulting and influencing one another quite early in the process. As the ear and eye simultaneously pick up gunshot and smoke, the two impressions immediately confer with each other. They perceive that the events are occurring in tandem, without conferencing with any higher authority. The picture of a rifle firing over an open field emerges in the observer’s brain. The steps are still sensation, routing, and perception. But at each step, add “the signals begin immediately communicating, influencing subsequent rounds of signal processing.” The last stage, perception, is not where the integration begins. The last step is where the integration culminates.
Which model is correct? The data are edging in the direction of the second model, but the truth is that nobody knows how it works. There are tantalizing suggestions that the senses actually help one another, and in a precisely coordinated fashion. This chapter is mostly interested in what happens after sensation and routing—after we achieve perception.
bottoms up, tops down
We can see how important this last step is by looking at what happens when it breaks down. Oliver Sacks reports on a patient he calls Dr. Richard who had lost various perceptual processing abilities. There wasn’t anything wrong with Dr. Richard’s vision. He just couldn’t always make sense of what he saw. When a friend walked into the room and sat down on a chair, he did not always perceive the person’s various body parts as belonging to the same body. Only when the person got up out of the chair would he suddenly recognize them as possessed by one person. If Dr. Richard looked at a photograph of people at a football stadium, he would identify the same colors of different people’s wardrobes as belonging “together” in some fashion. He could not see such commonalities as belonging to separate people. Most interesting, he could not always perceive multisensory stimuli as belonging to the same experience. This could be observed when Dr. Richard tried to watch someone speaking. He sometimes could not make a connection between the motion of the speaker’s lips and the speech. They would be out of sync; he sometimes reported the experience as if watching a “badly dubbed foreign movie.”
Given the survival advantage to seeing the world as a whole, scientists have been deeply concerned with the binding problem. They ask: Once the thalamus has done its distribution duties, what happens next? The information, dissected into sensory-size pieces and flung widely across the brain’s landscape, needs to be reassembled (something Dr. Richard was not very good at). Where and how does information from different senses begin to merge in the brain?
The where is easier than the how. We know that most of the sophisticated stuff occurs in regions known as association cortices. Association cortices are specialized areas that exist throughout the brain, including the parietal, temporal, and frontal lobes. They are not exactly sensory regions, and they are not exactly motor regions, but they are exactly bridges between them (hence the name association). Scientists think these regions use both bottom-up and top-down processes to achieve perception. As the sensory signals ascend through higher and higher orders of neural processing, these processes kick in. Here’s an example.
Author W. Somerset Maugham once said: “There are only three rules for writing a novel. Unfortunately, nobody knows what they are.” After your eyes read that sentence and the thalamus has spattered various aspects of the sentence all over the inside of your skull, bottom-up processors go to work. The visual system (which we will say more about in the Vision chapter) is a classic bottom-up processor. What happens? Feature detectors—which work like auditors in an accounting firm—greet the sentence’s visual stimuli. The auditors inspect every structural element in each letter of every word in Maugham’s quote. They write a report, a visual conception of letters and words. An upside-down arch becomes the letter “U.” Two straight lines at right angles become the letter “T.” Combinations of straight lines and curves become the word “three.” Written information has a lot of visual features in it, and this report takes a great deal of effort and time to organize. It is one of the reasons that reading is a relatively slow way to put information into the brain.
Next comes top-down processing. This can be likened to a board of directors reading the auditor’s report and then reacting to it. Many comments are made. Sections are analyzed in light of pre-existing knowledge. The board in your brain has heard of the word “three” before, for example, and it has been familiar with the concept of rules since you were familiar with anything. Some board members even have heard of W. Somerset Maugham before, and they recall to your consciousness a movie called Of Human Bondage, which you saw in a film history course. Information is added to the data stream or subtracted from the data stream. The brain can even alter the data stream if it so chooses. And it so chooses a lot.
Such interpretive activity is the domain of top-down processing. At this point, the brain generously lets you in on the fact that you are perceiving something. Given that people have unique previous experiences, they bring different interpretations to their top-down analyses. Thus, two people can see the same input and come away with vastly different perceptions. It is a sobering thought. There is no guarantee that your brain will perceive the world accurately, even if other parts of your body can.
So, life is filled with the complex qualities of sounds, visual images, shapes, textures, tastes, and odors, and the brain seeks to simplify this world by adding more confusion. This requires large groups of receptors, each one in charge of a particular sensory attribute, to act simultaneously. For us to savor the richness and diversity of perception, the central nervous system must integrate the activity of entire sensory populations. It does this by pushing electrical signals through an almost bewildering thicket of ever more complex, higher neural assemblies. Finally, you perceive something.
survival by teamwork
There are many types of synesthesia—more than 50, according to one paper. One of the strangest illustrates that even when the brain’s wiring gets confused, the senses still work together. There are some people who see a word and immediately experience a taste on their tongue. This isn’t the typical mouth-watering response, such as imagining the taste of a candy bar after hearing the word “chocolate.” This is like seeing the word “sky” in a novel and suddenly tasting a sour lemon in your mouth. A clever experiment showed that even when the synesthete could not recall the exact word, he or she could still get the taste, as long as there was some generalized description of the missing word. Data like these illustrate that sensory processes are wired to work together. Thus, the heart of the Brain Rule: Stimulate more of the senses.
The evolutionary rationale for this observation is simple: Our East African crib did not unveil its sensory information one sense at a time during our development. It did not possess only visual stimuli, like a silent movie, and then suddenly acquire an audio track a few million years later, and then, later, smells and odors and textures. By the time we came out of the trees, our ancestors were encountering a multisensory world and were already champions at experiencing it.
Some interesting experiments support these ideas. Several years ago, scientists were able to peer in on the brain using fMRI technology. They played a trick on their subjects: They showed a video of someone speaking but completely turned off the sound. When the researchers examined what the brain was doing, they found that the area responsible for processing the sound, the auditory cortex, was stimulated as if the person actually were hearing sound. If the person was presented with a person simply “making faces,” the auditory cortex was silent. It had to be a visual input related to sound. Clearly, visual inputs influence auditory inputs, even with the sound turned off.
In another experiment at about the same time, researchers showed short flashes of light near the subjects’ hands, which were rigged with a tactile stimulator. Sometimes researchers would turn on the stimulator while the flash of light was occurring, sometimes not. No matter how many times they did this, the visual portion of the brain always lighted up the strongest when the tactile response was paired with it. They could literally get a boost in the visual system by introducing touch. This effect is called multimodal reinforcement.
Multiple senses affect our ability to detect stimuli, too. Most people, for example, have a very hard time seeing a flickering light if the intensity of the light is gradually decreased. Researchers decided to test that threshold by precisely coordinating a short burst of sound with the light flickering off. The presence of sound actually changed the threshold. The subjects found that they could see the light way beyond their normal threshold if sound was part of the experience.
These data show off the brain’s powerful integrative instincts. Knowing that the brain cut its developmental teeth in an overwhelmingly multisensory environment, you might hypothesize that its learning abilities are increasingly optimized the more multisensory the environment becomes. You might further hypothesize that the opposite is true: Learning is less effective in a unisensory environment. That is exactly what you find, and it leads to direct implications for education and business.
the learning link
Cognitive psychologist Richard Mayer probably has done more than anybody else to explore the link between multimedia exposure and learning. He sports a 10-megawatt smile, and his head looks exactly like an egg (albeit a very clever egg). His experiments are just as smooth: Divide the room into three groups. One group gets information delivered via one sense (say, hearing), another the same information from another sense (say, sight), and the third group the same information delivered as a combination of the first two senses.
The groups in the multisensory environments always do better than the groups in the unisensory environments. They have more accurate recall. Their recall has better resolution and lasts longer, evident even 20 years later. Problem-solving improves. In one study, the group given multisensory presentations generated more than 50 percent more creative solutions on a problem-solving test than students who saw unisensory presentations. In another study, the improvement was more than 75 percent!
The benefits of multisensory inputs are physical as well. Our muscles react more quickly, our threshold for detecting stimuli improves, and our eyes react to visual stimuli more quickly. It’s not just combinations of sight and sound. When touch is combined with visual information, recognition learning leaps forward by almost 30 percent, compared with touch alone. These improvements are greater than what you’d predict by simply adding up the unisensory data. This is sometimes called supra-additive integration. In other words, the positive contributions of multisensory presentations are greater than the sum of their parts. Simply put, multisensory presentations are the way to go.
Many explanations have been put forth to explain these consistent findings, and most involve working memory. You might recall from Chapter 5 that working memory, formerly called short-term memory, is a complex work space that allows the learner to hold information for a short period of time. You might also recall its importance to the classroom and to business. What goes on in the volatile world of working memory deeply affects whether something that is taught will also be learned.
All explanations about multisensory learning also deal with a counter-intuitive property lurking at its mechanistic core: Extra information given at the moment of learning makes learning better. It’s like saying that if you carry two heavy backpacks on a hike instead of one, you will accomplish your journey more quickly. This is the “elaborative” processing that we saw in the chapter on short-term memory. Stated formally: It is the extra cognitive processing of information that helps the learner to integrate the new material with prior information. Multisensory experiences are, of course, more elaborate. Is that why they work? Richard Mayer thinks so. And so do other scientists, looking mostly at recognition and recall.
One more example of synesthesia supports this, too. Remember Solomon Shereshevskii’s amazing mental abilities? He could hear a list of 70 words once, repeat the list back without error (forward or backward), and then reproduce the same list, again without error, 15 years later. Shereshevskii had multiple categories of (dis)ability. He felt that some colors were warm or cool, which is common. But he also thought the number 1 was a proud, well-built man, and that the number 6 was a man with a swollen foot, which was not common. Some of his imaging was nearly hallucinatory. He related: “One time I went to buy some ice cream … I walked over to the vendor and asked her what kind of ice cream she had. ‘Fruit ice cream,she said. But she answered in such a tone that a whole pile of coals, of black cinders, came bursting out of her mouth, and I couldn’t bring myself to buy any ice cream after she had answered that way.”
Shereshevskii clearly is in his own mental universe, but he illustrates a more general principle. Synesthetes almost universally respond to the question “What good does this extra information do?” with an immediate and hearty “It helps you remember.” Given such unanimity, researchers have wondered for years if there is a relationship between synesthesia and advanced mental ability.
There is. Synesthetes usually display unusually advanced memory ability—photographic memory, in some cases. Most synesthetes report the odd experiences as highly pleasurable, which may, by virtue of dopamine, aid in memory formation. rules for the rest of us
Over the decades, Mayer has isolated a number of rules for multimedia presentation, linking what we know about working memory with his own empirical findings on how multimedia exposure affects human learning. Here are five of them in summary form:
1) Multimedia principle: Students learn better from words and pictures than from words alone.
2) Temporal contiguity principle: Students learn better when corresponding words and pictures are presented simultaneously rather than successively.
3) Spatial contiguity principle: Students learn better when corresponding words and pictures are presented near to each other rather than far from each on the page or screen.
4) Coherence principle: Students learn better when extraneous material is excluded rather than included.
5) Modality principle: Students learn better from animation and narration than from animation and on-screen text.
Though wonderfully empirical, these principles are relevant only to combinations of two senses: hearing and vision. We have three other senses also capable of contributing to the educational environment. Beginning with the story of a talented combat veteran, let’s explore what happens if we add just one more: smell.
nosing it out
I once heard a story about a man who washed out of medical school because of his nose. To understand his story, you have to know something about the smell of surgery. And you have to have killed somebody. Surgery can be a smelly experience. When you cut somebody’s body, you invariably cut their blood vessels. To keep the blood from interfering with the operation, surgeons use a cauterizing tool, hot as a soldering iron. It’s applied directly to the wound, burning it shut, filling the room with the acrid smell of smoldering flesh. Combat can smell the same way. And the medical student in question was a Vietnam vet with heavy combat experience. He didn’t seem to suffer any aversive effects when he came home. He had no post-traumatic stress disorder, and he became a high-functioning undergraduate, eventually accepted into medical school. But then the former soldier started his first surgery rotation. Entering the surgical suite, he promptly smelled the burning flesh from the cauterizer. The smell brought back to mind the immediate memory of an enemy combatant he had shot in the face, point blank, an experience he had suppressed for years. The memory literally doubled him over. He ran out of the room crying, the dying enemy’s strange gurgling sounds ringing in his ears, the noises of the evacuation helicopters in the distance. All that day, he relived the experience; later that night, he began to recall in succession other equally terrible events. He resigned from the program the next week.
This story illustrates something scientists have known for years: Smell can evoke memory. It’s called the Proust effect. Marcel Proust, the French author of the profoundly moving book Remembrance of Things Past, talked freely 100 years ago about smells and their ability to elicit long-lost memories. Typical experiments have investigated the unusual ability of a smell to enhance retrieval. Two groups of people might be assigned to see a movie together, for example, and then told to report to the lab for a memory test. The control group goes into an unmanipulated room and simply takes the test. The experimental group takes the test in a room flooded with the smell of popcorn. The results are then compared, scoring for number of events recalled, accuracy of events recalled, specific characteristics, and so on. The results of the test can be astonishing. Some researchers report that smell-exposed experimental groups can accurately retrieve twice as many memories as the controls. Others report a 20 percent improvement, still others only a 10 percent.
One way to react to these data is to say, “Wow.” Another is to ask, “Why the disparity in results?” One big reason is that the results depend on the type of memory being assessed and the methodology employed to obtain them. For example, researchers have found that certain types of memory are exquisitely sensitive to smells and other types nearly impenetrable. Odors appear to do their finest work when subjects are asked to retrieve the emotional details of a memory, as our medical student experienced, or to retrieve autobiographical memories. You get the best results if the smells are congruent. A movie test in which the smell of gasoline is pumped into the experimental room does not yield the same positive memory-retrieval results as the smell of popcorn does.
Odors are not so good at retrieving declarative memory. You can get smell to boost declarative scores, but only if the test subjects are emotionally aroused—usually, that means stressed—before the experiment begins. (For some reason, showing a film of young Australian aboriginal males being circumcised is a favorite way to do this). Recent tests, however, show that smell can improve declarative memory recall during sleep, a subject we will take up in a moment. Is there a reason why the Proust effect exists—why smell evokes memory? There might be, but to understand it, we have to know a little bit about how smell is processed in the brain.
Right between the eyes lies a patch of neurons about the size of a large postage stamp. This patch is called the olfactory region. The outer surface of this region, the one closest to the air in the nose, is the olfactory epithelium. When we sniff, odor molecules enter the nose chamber and collide with nerves there. This in itself is amazing, given that the chamber is always covered by a thick layer of snot. Somehow these persistent biochemicals penetrate the mucus and brush against little quill-like protein receptors that stud the nerves in the olfactory epithelium. The receptors can recognize a large number of smell-evoking molecules. When that happens, the neurons begin to fire excitedly, and you are well on your way to smelling something. The rest of the journey occurs in the brain. The now occupied nerves of the olfactory epithelium chat like teenagers on a cell phone to a group of nerves lying directly above them, in the olfactory bulb. These nerves help sort out the signals sent to it by the epithelium.
Here comes the interesting part of the story. Every other sensory system, at this point, must send a signal to the thalamus and ask permission to connect to the rest of the brain—including the higher levels where perception occurs. Not the nerves carrying information about smell. Like an important head of state in a motorcade, smell signals bypass the thalamus and go right to their brainy destinations, no meddling middle-man required.
One of those destinations is the amygdala, and it is at this point that the Proust effect begins to make some sense. As you recall, the amygdala supervises not only the formation of emotional experiences but also the memory of emotional experiences. Because smell directly stimulates the amygdala, smell directly stimulates emotions. Smell signals also head through the piriform cortex to the orbitofrontal cortex, a part of your brain just above and behind your eyes and deeply involved in decision making. So smell plays a role in decision making. It is almost as if the odor is saying, “My signal is so important, I am going to give you a memorable emotion. What are you going to do about it?”
Smell signals appear to be in a real hurry to take these shortcuts, so much so that olfactory receptor cells aren’t even guarded by a protective barrier. This is different from most other sensory receptor cells in the human body. Visual receptor neurons in the retina are protected by the cornea, for example. Receptor neurons that allow hearing in our ears are protected by the eardrum. The only things protecting receptor neurons for smell are boogers. Otherwise, they are directly exposed to the air.
ideas
There is no question that multiple cues, dished up via different senses, enhance learning. They speed up responses, increase accuracy, improve stimulation detection, and enrich encoding at the moment of learning. Yet we still aren’t harnessing these benefits on a regular basis in our classrooms and boardrooms. Here are a couple of ideas that come to mind.
Multisensory school lessons
As we learned in the Attention chapter, the opening moments of a lecture are cognitive hallowed ground. It is the one time teachers automatically have more student minds paying attention to them. If presentations during that critical time were multisensory, overall retention might increase. We discovered in the Memory chapters that repeating information in timed intervals helps stabilize memory. What if we introduced information as a multisensory experience, and then repeated not only the information but also one of the modes of presentation? The first re-exposure might be presented visually, for example; the next, auditorially; the third, kinesthetically. Would that encoding-rich schedule increase retention in real-world environments, boosting the already robust influence of repetition?
And let’s not continue to neglect our other senses. We saw that touch and smell are capable of making powerful contributions to the learning process. What if we began to think seriously about how to adopt them into the classroom, perhaps in combination with more traditional learning presentations? Would we capture their boosting effects, too?
One study showed that a combination of smell and sleep improved declarative-memory consolidation. The delightful experiment used a card game my sons and I play on a regular basis. The game involves a specialized 52-card deck we purchased at a museum, resplendent with 26 pairs of animals. We turn all of the cards face down, then start selecting two cards to find matches. It is a test of declarative memory. The one with the most correct pairs wins the game.
In the experiment, the control groups played the game normally. But the experimental groups didn’t. They played the game in the presence of rose scent. Then everybody went to bed. The control groups were allowed to sleep unperturbed. Soon after the snoring began in the experimental groups, however, the researchers filled their rooms with the same rose scent. Upon awakening, the subjects were tested on their knowledge of where the matches had been discovered on the previous day. Those subjects without the scent answered correctly 86 percent of the time. Those re-exposed to the scent answered correctly 97 percent of the time. Brain imaging experiments showed the direct involvement of the hippocampus. It is quite possible that the smell enhanced recall during the offline processing that normally occurs during sleep.
In the highly competitive world of school performance, there are parents who would die to give their kids an 11 percent edge over the competition. Some CEOs would appreciate such an advantage, too, in the face of anxious shareholders.
Sensory branding
Author Judith Viorst once said, “Strength is the capacity to break a chocolate bar into four pieces, and then eat just one of the pieces. She was of course referring to the power of the confection on self-will. It’s a testament to the power of emotion to incite action.
That’s just what emotions do: affect motivations. As we discussed in the Attention chapter, emotions are used by the brain to select certain inputs for closer inspection. Because smells stimulate areas in the brain responsible for creating emotions as well as memories, a number of business people have asked, “Can smell, which can affect motivation, also affect sales?”
One company tested the effects of smell on business and found a whopper of a result. Emitting the scent of chocolate from a vending machine, it found, drove chocolate sales up 60 percent. That’s quite a motivation. The same company installed a waffle-cone-smell emitter near a location-challenged ice cream shop (it was inside a large hotel and hard to find). Sales soared 50 percent, leading the inventor to coin the term “aroma billboard” to describe the technique.
Welcome to the world of sensory branding. An entire industry is beginning to pay attention to human sensory responses, with smell as the centerpiece. In an experiment for a clothing store, investigators subtly wafted the smell of vanilla in the women’s department, a scent known to produce a positive response among women. In the men’s department, they diffused the smell of rose maroc, a spicy, honeylike fragrance that had been pretested on men. The retail results were amazing. When the scents were deployed, sales doubled from their typical average in each department. And when the scents were reversed—vanilla for men and rose maroc for women—sales plummeted below their typical average. The conclusion? Smell works, but only when deployed in a particular way. “You can just use a pleasant scent and expect it to work,” says Eric Spangenberg, the scientist in charge of the work. “It has to be congruent.” In recognition of this fact, Starbucks does not allow employees to wear perfume on company time. It interferes with the seductive smell of the coffee they serve and its potential to attract customers.
Marketing professionals have begun to come up with recommendations for the use of smell in differentiating a brand: First, match the scent with the hopes and needs of the target market. The pleasant smell of coffee may remind a busy executive of the comforts of home, a welcome relief when about to close a deal. Second, integrate the odor with the “personality” of the object for sale. The fresh smell of a forest, or the salty odor of a beach, might evoke a sense of adventure more so than, say, the smell of vanilla, in potential buyers of SUVs. Remember the Proust effect, that smell can evoke memory.
Smells at work (not coming from the fridge)
What about the role of learning in a business setting? Two ideas come to mind, based loosely on my teaching experiences. I occasionally teach a molecular biology class for engineers, and one time I decided to do my own little Proust experiment. (There was nothing rigorous about this little parlor investigation; it was simply an informal inquiry.) Every time I taught one section on an enzyme (called RNA polymerase II), I prepped the room by squirting the perfume Brut on one wall. In an identical class in another building, I taught the same material, but I did not squirt Brut when describing the enzyme. Then I tested everybody, squirting the perfume into both classrooms. Every time I did this experiment, I got the same result. The people who were exposed to the perfume during learning did better on subject matter pertaining to the enzyme—sometimes dramatically better—than those who were not.
And that led me to an idea. Many businesses have a need to teach their clients about their products, from how to implement software to how to repair airplane engines. For financial reasons, the classes are often compressed for time and packed with information, 90 percent of which is forgotten a day later. (For most declarative subjects, memory degradation starts the first few hours after the teaching is finished.) But what if the teacher paired a smell with each lesson, as in my Brut experiment? One might even expose the students to the smell while they are asleep. The students could not help but associate the autobiographical experience of the class—complete with the intense transfer of information—with the odorant.
After the class, the students (let’s say they’re learning to repair airplane engines) return to their company. Two weeks later, they are confronted with a room full of newly broken engines to repair. Most of them will have forgotten something in the intense class they took and need to review their notes. This review would take place in the presence of the smell they encountered during the learning. Would it give a boost to their memories? What if they were exposed to the smell while they were in the shop repairing the actual engines? The enhanced memory might improve performance, even cut down on errors.
Sound preposterous? Possibly. Indeed, one must be careful to tease out context-dependent learning (remember those dive suits from Chapter 5) from true multisensory environments. But it’s a start toward thinking about learning environments that go beyond the normal near-addiction to visual and auditory information. It is an area where much potential research fruit lies—truly a place for brain scientists, educators and business professionals to work together in a practical way.
Summary
Rule #9
Stimulate more of the senses at the same time.
• We absorb information about an event through our senses, translate it into electrical signals (some for sight, others from sound, etc.), disperse those signals to separate parts of the brain, then reconstruct what happened, eventually perceiving the event as a whole.
• The brain seems to rely partly on past experience in deciding how to combine these signals, so two people can perceive the same event very differently.
• Our senses evolved to work together—vision influencing hearing, for example—which means that we learn best if we stimulate several senses at once.
• Smells have an unusual power to bring back memories, maybe because smell signals bypass the thalamus and head straight to their destinations, which include that supervisor of emotions known as the amygdala.
