Chapter 7 — The Hungry Mind

"The Creator, when he obliges man to eat, invites him to do so by appetite, and rewards him by pleasure." — Jean Anthelme Brillat-Savarin, Physiologie du Goût, Aphorism V, 1825

By now the reader has been led, chapter by patient chapter, through nearly the whole physical apparatus of eating: the tongue's five true tastes, the nose's silent government of nearly everything we call flavour, the browning pan, the seasoning compass, the umami bond, and, in the chapter just closed, the mouth's second and stranger nervous system, alight with borrowed fires and false frosts. It would be tidy to conclude, on the strength of all that anatomy, that flavour is manufactured entirely below the neck — assembled from taste buds and olfactory receptors and trigeminal nerve endings, parcelled up, and delivered to a brain that merely reads the label and passes judgment. It would also be quite wrong. Every one of those signals arrives at its destination not as a finished verdict but as a raw dispatch, provisional and slightly ambiguous, and it is only in the last few inches of the journey — in the brain itself — that flavour is actually made. The same glass of wine tastes different poured from a bottle believed cheap than from one believed dear; the same biscuit tastes staler in a silent room than a noisy one; the same custard tastes sweeter from a white bowl than a black one; the same yoghurt tastes denser from one spoon than another of identical size — though in not one of these cases has a single molecule been added, subtracted, or so much as stirred. This chapter concerns the last and least visible ingredient in any dish: the diner's own mind, which turns out to be not a passive judge of the meal but one of its co-authors, quietly rewriting the menu before the first bite is ever taken.

It is worth being honest, at the outset, about how unsettling this can sound. We are accustomed to thinking of taste as a private but reliable instrument, rather like a thermometer: it may vary a little from person to person, but surely it measures something fixed, out there, in the food itself. The research gathered in this chapter suggests something closer to the opposite. Flavour perception behaves less like a thermometer and more like a jury — a body that takes evidence from many witnesses, some of them frankly unreliable, weighs testimony that has nothing directly to do with the food at all, and reaches a verdict that feels, to the diner, every bit as certain and as singular as a simple reading off a dial. Nothing in what follows is intended to suggest that flavour is therefore an illusion, or that objective differences between a good dish and a poor one do not exist; a rancid oil and a fresh one will never swap places no matter how the plate is lit. It is intended to suggest something subtler and, to a naturalist's eye, considerably more interesting: that the boundary between the food and the diner is far less fixed than either party generally supposes, and that a great many of the qualities we describe as belonging to a dish — its richness, its freshness, its sheer deliciousness — are in fact collaborations, struck fresh at every sitting, between a plate that cannot change and a mind that never stops working.

The colour of expectation

In the 1930s and 1940s, long before any psychologist had thought to study fine dining, an American consultant to the packaging industry named Louis Cheskin noticed something that ought to have been impossible. Shown two tubs of margarine, chemically identical in every particular, consumers rated the one dyed a warm butter-yellow as tastier, fresher, and altogether more like butter than the one left in its natural, faintly unappetising white — despite tasting, quite literally, the same product from the same vat. Cheskin called the effect sensation transference: the unconscious habit of transferring one's impression of a product's packaging, colour, or presentation directly onto one's impression of the product itself, so thoroughly that the eater can no longer separate the two.[^1] Cheskin was selling soap and margarine, not gastronomy, but the principle he identified would resurface, seventy years later, as the founding insight of a discipline the Oxford experimental psychologist Charles Spence named gastrophysics: the systematic study of how expectation, primed by everything surrounding a meal, physically alters the taste of the meal itself.

Spence's laboratory has spent the better part of two decades chasing sensation transference into the dining room, and the results are, to a naturalist's eye, wonderfully strange. In one now-celebrated demonstration, an identical dessert — a frozen strawberry mousse — was served to diners on plates of two colours, black and white; the very same mousse, eaten from the white plate, was rated as measurably sweeter, more flavourful, and simply better liked than when eaten from the black one.[^2] Colour alone, it appears, primes the palate before the spoon has even been lifted. A still older and more dramatic demonstration comes from Bordeaux, where in 2001 the researcher Frédéric Brochet, working with his supervisors Gil Morrot and Denis Dubourdieu, offered a panel of fifty-four oenology students two glasses of the same white wine — save that one had been tinted red with an odourless, flavourless dye. Tasting blind, professionals trained for years to describe wine with precision, the panel overwhelmingly described the dyed glass using the standard vocabulary of red wine — notes of blackcurrant, cherry, tannin — abandoning the language of white wine almost entirely, though the liquid in the glass was, but for its borrowed hue, unchanged.[^3] The eye, it transpires, does not merely accompany the tasting. It gets there first, briefing the palate before the palate has done any work of its own, and it is not easily overruled by whatever the tongue reports afterwards.

The number on the label

If colour can rewrite a wine's flavour before it is poured, a still more abstract signal — a number printed on a label — can rewrite it after the glass is already in hand. In 2008 a team led by the neuroeconomist Hilke Plassmann, working across Caltech and Stanford, poured an identical modest Cabernet Sauvignon into identical glasses, labelled some five dollars a bottle and others forty-five, and had volunteers taste and rate them while lying inside a functional MRI scanner. The wine believed to be the costlier of the two was rated as significantly more pleasant — an unremarkable finding on its own, easily dismissed as mere snobbery or performance — except that the scanner told a less dismissible story. Activity in the medial orbitofrontal cortex, a region of the brain reliably associated with the experience of pleasure rather than its polite performance, rose measurably higher when tasting the "expensive" glass.[^4] The price tag was not merely making volunteers claim to enjoy the wine more; it appeared to be altering, at the level of the brain's own reward circuitry, how much they actually did. A name works a milder version of the same trick: a dish introduced to a diner with a story, a place of origin, or simply a more evocative description on the menu, arrives at the palate already dressed in expectation, and expectation, this whole chapter argues, is never merely decorative. It is one of the ingredients. The same logic runs in reverse, and rather less happily, when a trusted name is withdrawn: diners told, accurately, that a familiar soft drink or coffee has been secretly reformulated will frequently report that it tastes worse, even when blind panels detect no difference whatsoever between old and new recipe, simply because the story attached to the product — this is the one I have always liked — has been disturbed. The label, in other words, is never merely information sitting beside the food. It is read by the same palate that reads the food, and it is read first.

The weight of the world

If the eye and the label speak first, the hand is not far behind — though its testimony, when examined closely, turns out to be more curious than the tidy version of the story usually allows. In 2013 Charles Spence and his colleague Vanessa Harrar set out to test whether the sheer physical weight of a piece of cutlery could alter the taste of food eaten from it, using a set of ordinary plastic teaspoons, secretly weighted to different degrees, and identical portions of yoghurt. The instinctive prediction — the one sensation transference would seem to demand, and the one many popular accounts of the study still repeat — is that the heavier spoon should read as the more expensive, more luxurious implement, and lend its gravity to the food. The result was the opposite: yoghurt eaten from the lighter of the plastic spoons was rated as denser, more expensive and better liked than the same yoghurt eaten from a spoon artificially weighted down.[^5] The same set of experiments found that white yoghurt tasted sweeter from a white spoon than a black one, with the pattern reversing for pink-tinted yoghurt, and — oddest of all — that food sampled from the flat of a knife was reliably judged saltier than identical food taken from a spoon, a fork, or a cocktail stick.

The lesson here is not that heft is irrelevant — other studies, using genuine silver spoons against genuine steel ones, or heavy glass tumblers against flimsy plastic cups, do find that real weight, in a material the diner expects to be heavy, reads as quality, exactly as sensation transference would predict.[^6] The lesson, rather, is that no single physical property acts alone: it is weight measured against expectation that moves the needle, and a plastic spoon is expected, by the hand that holds it, to be light. Made unexpectedly heavy, it does not borrow the gravitas of silver; it simply announces, faintly and without words, that something about this spoon is not as it should be — and the diner, unable to say quite what, marks the food down instead. Expectation, once again, turns out to be doing the deciding; weight is merely one more messenger it may believe or doubt.

The noisy table

We met, in the previous chapter, the "sonic chip" experiment, in which Massimiliano Zampini and Charles Spence discovered that amplifying the high-frequency crackle of a person's own bite made a crisp taste crisper and fresher in the eating.[^7] That experiment concerned a sound the diner produces; ambient sound — the noise of the room itself, entirely outside the diner's control — turns out to be just as powerful an editor of taste, and considerably less flattering in its effects. Researchers at Cornell, Kimberly Yan and Robin Dando, seated volunteers in loud background noise of roughly the intensity of a cruising airliner cabin and had them rate the five basic tastes against the same tastants sampled in ordinary quiet. Sweetness, they found, was significantly suppressed by the din; saltiness, sourness and bitterness were largely unaffected; and umami, remarkably, grew stronger the louder the room became.[^8]

The effect had, in fact, already been discovered by accident, in the sky itself. Cabin crews had long observed that airline passengers drink a peculiar quantity of tomato juice relative to any other setting — enough that Lufthansa, curious about the pattern, commissioned the Fraunhofer Institute for Building Physics to investigate. That industry study, released in 2010, concluded that cabin pressure and engine roar together dull sweetness and blunt the perception of aroma, while leaving the deep, savoury pull of umami-rich tomato juice comparatively untouched — a finding that fits neatly, if a touch less formally, with the later Cornell laboratory result.[^9] Aeroplane food is not merely a victim of poor catering, in other words; it is fighting, from the outset, a losing battle against some eighty-five decibels of engine noise, a battle it wins only when the menu leans on tomato, parmesan, miso, and their broadly savoury kin. It is worth adding, in fairness, that the Fraunhofer findings were commissioned by an airline with an obvious commercial interest in the answer, which makes them a rather less independent piece of evidence than the peer-reviewed Cornell work — a small but useful illustration of a rule this whole compendium tries to observe: that even a delightful finding deserves to be weighed by the company that paid for it.

The great time machine

Of all the mind's contributions to flavour, none is stranger or more sudden than memory, and no one has described its workings more precisely than a novelist with no interest in science at all. Every flavour we have discussed in this volume is, in fact, partly learned rather than simply detected: an infant shows no innate preference for the specific taste of chilli, coffee, or blue cheese, all three among the most prized flavours of adulthood, and acquires a taste for each only through repeated, often effortful exposure, generally in the company of others already enjoying it. Flavours become attached, by ordinary association, to the rooms in which we first ate them, the people who served them, and the emotional weather of the afternoon — which is simply to say that every dish we eat is quietly being filed away for later, whether or not we notice the filing taking place. Nowhere has this quiet mechanism been more exactly captured than in a single paragraph of fiction. Early in Swann's Way, the first volume of Marcel Proust's In Search of Lost Time, the narrator, cold and dispirited on a winter's afternoon, is offered a cup of lime-blossom tea and one of those small, scallop-shaped cakes called petites madeleines — a combination, he tells us, he did not ordinarily take. He dips a morsel in the tea, raises the spoon to his lips, and something happens to him that no amount of willed remembering had managed in decades.

We shall let the narrator describe it himself, and then attempt to explain it, in the Field Note below.

Field Note — The Madeleine

"No sooner had the warm liquid mixed with the crumbs touched my palate than a shudder ran through me and I stopped, intent upon the extraordinary thing that was happening to me. An exquisite pleasure had invaded my senses, something isolated, detached, with no suggestion of its origin." So Marcel Proust's narrator describes the taste that, within a page or two, unspools an entire lost childhood in the town of Combray — not summoned by effort, but ambushed by a flavour, arriving whole and involuntary, long after the conscious search for that same childhood had been abandoned as fruitless. So exact and so widely recognised is this experience that psychologists now speak, without irony, of the Proust phenomenon: the well-documented tendency of smells and tastes, far more reliably than sights or sounds, to trigger sudden, vivid, emotionally charged autobiographical memory, complete and unbidden.

The novelist could not have known the anatomical reason for his own experience, but neuroscience has since supplied it, and it is unexpectedly tidy. Every other sense — sight, hearing, ordinary touch — first passes through the thalamus, a kind of central relay station that sorts incoming signals before passing them on for conscious processing. Smell alone skips this queue entirely. Signals from the olfactory bulb travel by direct, evolutionarily ancient pathways straight into the amygdala, which assigns emotional weight, and the hippocampus, which encodes and retrieves long-term memory — the very structures that give old songs and half-forgotten photographs their power, reached by aroma without a single intermediate stop along the way. Flavour, which is chiefly retronasal smell, therefore keeps a private line open to memory that colour and sound do not enjoy, which is why a single scent can dissolve forty years in the time it takes to lift a spoon, while a photograph of the very same forty years, examined at leisure, moves us so very much less.

The madeleine itself, incidentally, is beside the point, and Proust seems to have known it: he tells us the sensation arrived "with no suggestion of its origin," the memory of Combray surfacing only afterwards, coaxed forth with real and visible effort across several further paragraphs. This is the Proust phenomenon exactly as laboratories now describe it — the emotion and the sense of overwhelming familiarity arrive first and instantly, well ahead of any clear image of what is actually being remembered, precisely because the amygdala's alarm bell rings before the hippocampus has finished retrieving the file. The madeleine did not remind the narrator of his aunt's house; for one long, disorientating moment, it simply was the feeling of his aunt's house, arriving before he had the least idea why — which is, when the reader stops to consider it, a very close description of what happens to any of us confronted, without warning, by the smell of a particular soap, a particular rain-soaked pavement, or a particular grandmother's kitchen.

<figure> <svg xmlns="http://www.w3.org/2000/svg" width="100%" viewBox="0 0 640 640" role="img"> <title>The Confederation of the Senses</title> <defs> <pattern id="hs1" width="4" height="4" patternUnits="userSpaceOnUse" patternTransform="rotate(45)"><line x1="0" y1="0" x2="0" y2="4" stroke="#a9906c" stroke-width="0.5"/></pattern> <pattern id="hs2" width="3" height="3" patternUnits="userSpaceOnUse" patternTransform="rotate(45)"><line x1="0" y1="0" x2="0" y2="3" stroke="#c8b79a" stroke-width="0.4"/></pattern> <symbol id="fl" overflow="visible"><path d="M0,-5 L5,0 L0,5 L-5,0 Z" fill="#43331f"/></symbol> <symbol id="dm" overflow="visible"><path d="M0,-3.5 L3.5,0 L0,3.5 L-3.5,0 Z" fill="#6f5a40"/></symbol> </defs> <rect x="12" y="12" width="616" height="616" fill="none" stroke="#43331f" stroke-width="1"/> <rect x="17" y="17" width="606" height="606" fill="none" stroke="#6f5a40" stroke-width="0.5"/> <use href="#fl" x="12" y="12"/><use href="#fl" x="628" y="12"/><use href="#fl" x="12" y="628"/><use href="#fl" x="628" y="628"/> <text x="320" y="40" text-anchor="middle" font-family="Georgia, 'Times New Roman', serif" font-size="14" letter-spacing="1.5" fill="#43331f">THE CONFEDERATION OF THE SENSES</text> <line x1="225" y1="50" x2="415" y2="50" stroke="#6f5a40" stroke-width="0.5"/> <circle cx="320" cy="320" r="210" fill="none" stroke="#c8b79a" stroke-width="0.6"/>  <g stroke="#6f5a40" stroke-width="0.7"> <line x1="320" y1="265" x2="320" y2="140"/><line x1="368" y1="293" x2="476" y2="230"/><line x1="368" y1="348" x2="476" y2="410"/> <line x1="320" y1="375" x2="320" y2="500"/><line x1="272" y1="348" x2="164" y2="410"/><line x1="272" y1="293" x2="164" y2="230"/> </g> <use href="#dm" x="320" y="202"/><use href="#dm" x="422" y="261"/><use href="#dm" x="422" y="379"/><use href="#dm" x="320" y="438"/><use href="#dm" x="218" y="379"/><use href="#dm" x="218" y="261"/>  <circle cx="320" cy="320" r="55" fill="url(#hs2)" stroke="#43331f" stroke-width="1.2"/> <circle cx="320" cy="320" r="48" fill="none" stroke="#6f5a40" stroke-width="0.5"/> <line x1="296" y1="306" x2="344" y2="306" stroke="#6f5a40" stroke-width="0.5"/> <text x="320" y="326" text-anchor="middle" font-family="Georgia, serif" font-size="16" letter-spacing="3" fill="#43331f">FLAVOUR</text> <line x1="296" y1="335" x2="344" y2="335" stroke="#6f5a40" stroke-width="0.5"/>  <circle cx="320" cy="110" r="30" fill="url(#hs2)" stroke="#43331f" stroke-width="1"/> <ellipse cx="320" cy="110" rx="15" ry="8" fill="none" stroke="#43331f" stroke-width="1"/> <circle cx="320" cy="110" r="5" fill="none" stroke="#43331f" stroke-width="0.8"/><circle cx="320" cy="110" r="2" fill="#43331f"/> <text x="320" y="153" text-anchor="middle" font-family="Georgia, serif" font-style="italic" font-size="11" fill="#43331f">Sight</text>  <circle cx="502" cy="215" r="30" fill="url(#hs2)" stroke="#43331f" stroke-width="1"/> <path d="M493,206 C505,204 513,212 509,222 C507,227 500,228 495,224" fill="none" stroke="#43331f" stroke-width="1"/> <circle cx="500" cy="221" r="1.6" fill="#43331f"/> <path d="M505,196 q4,-4 2,-9" fill="none" stroke="#6f5a40" stroke-width="0.6"/><path d="M513,199 q4,-3 3,-8" fill="none" stroke="#6f5a40" stroke-width="0.6"/> <text x="502" y="258" text-anchor="middle" font-family="Georgia, serif" font-style="italic" font-size="11" fill="#43331f">Smell</text>  <circle cx="502" cy="425" r="30" fill="url(#hs2)" stroke="#43331f" stroke-width="1"/> <path d="M490,412 C505,408 518,412 518,428 C518,440 505,444 495,440 C486,436 486,420 490,412 Z" fill="url(#hs1)" stroke="#43331f" stroke-width="1"/> <path d="M502,414 Q505,428 500,438" fill="none" stroke="#6f5a40" stroke-width="0.6"/> <circle cx="497" cy="418" r="0.8" fill="#43331f"/><circle cx="508" cy="420" r="0.8" fill="#43331f"/><circle cx="500" cy="431" r="0.8" fill="#43331f"/> <text x="502" y="468" text-anchor="middle" font-family="Georgia, serif" font-style="italic" font-size="11" fill="#43331f">Taste</text>  <circle cx="320" cy="530" r="30" fill="url(#hs2)" stroke="#43331f" stroke-width="1"/> <path d="M305,517 C305,507 335,507 335,517 L335,540 C335,548 305,548 305,540 Z" fill="url(#hs1)" stroke="#43331f" stroke-width="1"/> <path d="M312,520 Q320,516 328,520" fill="none" stroke="#6f5a40" stroke-width="0.5"/><path d="M310,526 Q320,521 330,526" fill="none" stroke="#6f5a40" stroke-width="0.5"/><path d="M309,533 Q320,527 331,533" fill="none" stroke="#6f5a40" stroke-width="0.5"/><path d="M310,540 Q320,535 330,540" fill="none" stroke="#6f5a40" stroke-width="0.5"/> <text x="320" y="573" text-anchor="middle" font-family="Georgia, serif" font-style="italic" font-size="11" fill="#43331f">Touch</text>  <circle cx="138" cy="425" r="30" fill="url(#hs2)" stroke="#43331f" stroke-width="1"/> <path d="M126,410 C146,404 156,418 152,432 C150,442 140,447 130,443 C123,440 122,433 127,430" fill="none" stroke="#43331f" stroke-width="1"/> <path d="M133,417 C142,415 146,423 141,429 C139,431 135,430 135,427" fill="none" stroke="#6f5a40" stroke-width="0.7"/> <text x="138" y="468" text-anchor="middle" font-family="Georgia, serif" font-style="italic" font-size="11" fill="#43331f">Sound</text>  <circle cx="138" cy="215" r="30" fill="url(#hs2)" stroke="#43331f" stroke-width="1"/> <path d="M122,206 C122,195 132,188 142,190 C152,187 160,196 157,206 C160,212 156,219 149,219 L149,226 L141,226 L141,220 C130,221 122,214 122,206 Z" fill="url(#hs1)" stroke="#43331f" stroke-width="1"/> <path d="M128,201 Q134,196 140,201 Q146,206 152,201" fill="none" stroke="#6f5a40" stroke-width="0.6"/> <path d="M128,209 Q134,205 140,209" fill="none" stroke="#6f5a40" stroke-width="0.6"/> <text x="138" y="258" text-anchor="middle" font-family="Georgia, serif" font-style="italic" font-size="11" fill="#43331f">Mind</text> </svg> <figcaption><em>Plate 13. Flavour as the meeting-place of taste, smell, touch, sound, sight and mind</em></figcaption> </figure>

<figure> <svg xmlns="http://www.w3.org/2000/svg" width="100%" viewBox="0 0 640 420" role="img"> <title>The Madeleine and the Cup</title> <defs> <pattern id="hs1" width="4" height="4" patternUnits="userSpaceOnUse" patternTransform="rotate(45)"><line x1="0" y1="0" x2="0" y2="4" stroke="#a9906c" stroke-width="0.5"/></pattern> <pattern id="hs2" width="3" height="3" patternUnits="userSpaceOnUse" patternTransform="rotate(45)"><line x1="0" y1="0" x2="0" y2="3" stroke="#c8b79a" stroke-width="0.4"/></pattern> <symbol id="fl" overflow="visible"><path d="M0,-5 L5,0 L0,5 L-5,0 Z" fill="#43331f"/></symbol> </defs> <rect x="12" y="12" width="616" height="396" fill="none" stroke="#43331f" stroke-width="1"/> <rect x="17" y="17" width="606" height="386" fill="none" stroke="#6f5a40" stroke-width="0.5"/> <use href="#fl" x="12" y="12"/><use href="#fl" x="628" y="12"/><use href="#fl" x="12" y="408"/><use href="#fl" x="628" y="408"/> <text x="320" y="38" text-anchor="middle" font-family="Georgia, 'Times New Roman', serif" font-size="15" letter-spacing="2" fill="#43331f">THE MADELEINE & THE CUP</text> <line x1="235" y1="49" x2="405" y2="49" stroke="#6f5a40" stroke-width="0.5"/> <text x="320" y="63" text-anchor="middle" font-family="Georgia, serif" font-style="italic" font-size="11" fill="#6f5a40">an emblem of involuntary memory</text>  <line x1="70" y1="308" x2="580" y2="308" stroke="#c8b79a" stroke-width="0.6"/>  <path d="M150,240 C155,215 175,205 200,205 C225,207 240,220 240,240 C240,260 225,275 200,277 C175,278 155,268 150,240 Z" fill="url(#hs2)" stroke="#43331f" stroke-width="1"/> <g fill="none" stroke="#6f5a40" stroke-width="0.6"> <path d="M156,240 Q182,213 200,206"/><path d="M156,240 Q195,213 222,210"/><path d="M156,240 Q205,222 236,222"/><path d="M156,240 L238,240"/><path d="M156,240 Q205,258 236,258"/><path d="M156,240 Q195,267 222,270"/><path d="M156,240 Q182,267 200,277"/> </g> <line x1="218" y1="214" x2="150" y2="186" stroke="#6f5a40" stroke-width="0.5"/> <text x="147" y="183" text-anchor="end" font-family="Georgia, serif" font-style="italic" font-size="11" fill="#43331f">shell ridges</text> <text x="195" y="340" text-anchor="middle" font-family="Georgia, serif" font-style="italic" font-size="11" fill="#43331f">the madeleine</text>  <g fill="none" stroke="#a9906c" stroke-width="0.6"> <path d="M440,236 C435,220 448,210 442,195 C438,183 450,175 445,160"/> <path d="M457,236 C462,220 450,208 458,192 C464,180 454,170 460,158"/> </g>  <ellipse cx="458" cy="300" rx="72" ry="16" fill="url(#hs2)" stroke="#43331f" stroke-width="1"/>  <path d="M420,250 C416,275 426,296 458,298 C490,296 500,275 496,250 Z" fill="url(#hs1)" stroke="#43331f" stroke-width="1"/>  <path d="M494,258 C508,258 510,275 498,280 C490,283 486,275 492,270" fill="none" stroke="#43331f" stroke-width="1.1"/>  <ellipse cx="458" cy="250" rx="38" ry="10" fill="url(#hs2)" stroke="#43331f" stroke-width="1"/> <ellipse cx="458" cy="250" rx="31" ry="7" fill="none" stroke="#6f5a40" stroke-width="0.6"/> <text x="458" y="340" text-anchor="middle" font-family="Georgia, serif" font-style="italic" font-size="11" fill="#43331f">porcelain cup</text> </svg> <figcaption><em>Plate 14. The madeleine and the teacup: involuntary memory's ordinary trigger</em></figcaption> </figure>

Room for pudding

Every reader will recognise a phenomenon that has, nonetheless, needed a scientific name: the diner who claims, quite sincerely, to be full to the point of discomfort after a large main course, and who then discovers, at the sight of the dessert trolley, an entirely fresh appetite. This is not weakness of will, nor is it a trick of the eyes. It is a genuine and measurable effect named sensory-specific satiety, first demonstrated in 1981 by the Oxford researchers Barbara Rolls, Edmund Rolls and their colleagues, who had volunteers rate the pleasantness of a variety of foods, fed them one of those foods to the point of fullness, and then asked them to rate the whole array again. The food just eaten dropped sharply in appeal, precisely as ordinary satiety would predict — but foods of a markedly different flavour, texture, or category, sweet chief among them, kept nearly all of their original appeal, undiminished by a stomach that was, by any honest measure, already full.[^10] The body, in other words, does not merely track how full the stomach is; it tracks, sense by sense, precisely which pleasures have already been indulged, and keeps the account open for any that have not.

Evolution's logic here is not hard to reconstruct. A creature that stopped eating the instant any single food ceased to delight would be at grave risk of nutritional tunnel vision, gorging on whatever happened to be most abundant nearby while starving quietly of everything else a varied diet supplies — the vitamins in the leaf, the minerals in the marrow, the protein in the grain the fruit alone cannot provide. Sensory-specific satiety guards against exactly this trap, gently nudging the eater from the meat to the vegetables to the bread to, finally, the sweet, and ensuring that a table laid with real variety will be more thoroughly explored, and more completely nourished, than one offering only a single dish however excellent. It is, in the most literal sense, the physiological argument for pudding: not indulgence, but an ancient and rather sensible insurance policy against monotony, still quietly operating at the end of every meal we eat, whatever the diner's belt may privately be reporting.

The same mechanism, reader, explains a great deal of what a menu is actually for. The classical progression of a long meal — a light, sharp opening course to rouse the appetite, a fish course, a meat course, cheese, and only then something sweet — is not merely a parade of courses arranged by tradition or convenience. It is, whether or not any given chef could name the psychology behind it, a deliberate tour through the very faculty Rolls described: each new course arrives with a flavour, temperature or texture sufficiently different from the last to sidestep the satiety already building for its predecessor, so that an eater genuinely full of duck can nonetheless discover, quite honestly, an appetite for a wedge of Époisses, and an eater full of cheese can discover, honestly again, an appetite for a spoonful of something cold and sweet. The tasting menu, in this light, is less a triumph of a chef's stamina over a diner's than a fairly precise piece of applied neuroscience, arrived at by trial and error many generations before the laboratory caught up with the kitchen.

The pleasure of contrast

If satiety explains why we welcome a change of flavour, it does not yet explain why certain changes please us so much more than others — why chocolate and salt, or duck and orange, or chilli and lime, seem so much more than the simple sum of their parts. One influential theory, associated above all with the chef Heston Blumenthal and the flavour chemist François Benzi, proposes that harmonious pairings share a hidden chemical kinship: ingredients that taste good together, the theory holds, very often share a significant number of the same aroma compounds, detectable by gas chromatography if not by name. The theory's founding anecdote is now well worn but irresistible: Blumenthal, experimenting with salty and sweet combinations, found that white chocolate and caviar tasted remarkably well matched, and on having both analysed discovered that they shared, as one of their principal aroma notes, the same compound, trimethylamine.[^11] The Belgian firm Foodpairing, built on this premise with the flavour scientist Bernard Lahousse, has since assembled a substantial database mapping thousands of aroma molecules across ingredients, in service of chefs hunting for the next caviar and white chocolate.

The tidy version of this theory has not, however, survived contact with wider evidence unscathed, and it is worth reporting the complication honestly, in the spirit this whole volume has tried to keep throughout. A large 2011 study of flavour networks, examining tens of thousands of recipes drawn from several culinary traditions, found that Western cuisines do indeed lean toward pairing ingredients that share flavour compounds — but East Asian cuisines, on the whole, tend to do very nearly the opposite, favouring combinations of ingredients that share hardly any aroma compounds at all.[^12] Shared chemistry, in other words, is not a universal law of deliciousness so much as one regional habit among several, and it sits alongside an older, simpler, and rather more reliable principle: the pleasure of straightforward contrast — the cold cream against the hot tart, the crisp crackling against the yielding meat beneath it, the sour pickle cutting the richness of the fat, the sweet mango against the salt and chilli of a Thai som tam, the sharp vinaigrette waking a rich terrine. A great many of the world's most admired dishes turn out, on inspection, to be built like small arguments, in which one taste, texture, or temperature is stated only to be answered by its opposite. Balance, that most ancient of culinary instincts, may in the end owe less to any single chemical rulebook than to a mind that simply delights in being surprised twice in a single mouthful — once by a flavour, and once again by whatever answers it. The reader who has followed this compendium from its opening chapter will notice that contrast has, in truth, been the quiet subject of the whole book: sweetness needing bitterness to be legible as sweetness at all, salt suppressing bitterness so that fruit and umami can be heard, acid cutting fat, the crackling contrast of a good crust against a tender crumb. Balance is not the absence of extremes; it is their careful, opposed presence, held in a single mouthful long enough for the mind to enjoy the argument between them.

The story on the plate

One further ingredient belongs in this catalogue, though no chemist could weigh it and no laboratory has ever quite captured it in a jar: the story a diner is told about what they are eating. Everything gathered in this chapter so far — the colour of the plate, the price on the label, the weight of the spoon — works by the same underlying mechanism as a narrative, priming the mind before the tongue has cast its own vote, and a story is simply the most elaborate and most human version of that priming. Told that a cheese has been aged in a particular cave for a particular number of months, that a fish was landed that same morning by a named boat, or that a recipe has been carried unaltered across four generations of a single family, a diner does not merely feel better disposed toward the meal in some vague sentimental sense. Every mechanism catalogued in this chapter — sensation transference, the price effect, the expectation that governs even the humble spoon — gives good reason to think that story changes the eating itself, tuning the same expectations that a coloured plate or a printed number tunes, only by gentler and more literary means. This is not a licence for kitchens to lie: a fabricated story, discovered, curdles trust and, with it, the very pleasure it was meant to enhance, and no honest chapter in this volume would counsel a cook to dress a frozen fillet in an invented pedigree. But a true story, well told, is not decoration laid over the food. On the evidence gathered here, it is very nearly a seasoning in its own right, one Brillat-Savarin understood intuitively long before any scanner could show it at work in the brain.

Hunger, company, and the oldest seasoning

We arrive, finally, at the least measurable and most powerful ingredient of all. No laboratory instrument records it, and no menu lists it, yet every cook has felt its absence: the state of the diner. Cicero, in his treatise De Finibus, observed that hunger is the seasoning of food — cibi condimentum esse famem — and versions of the same old truth recur across nearly every European language and several beyond it, which suggests it needed discovering only once, by whoever first noticed that stale bread eaten ravenously beats a feast approached without appetite. Hunger sharpens every sense this volume has catalogued: the threshold for detecting sweetness drops, the brain's reward circuitry responds more avidly to the smell of cooking, and food that would strike a satisfied diner as merely adequate becomes, to a hungry one, memorable, even noble. It is the plainest and least fashionable of all the effects in this chapter, and for that very reason the one professional kitchens can least afford to forget: a tasting menu is at its most generous, and its most dangerous, in the first three courses, before the body's own machinery of satisfaction has begun quietly working against the chef.

Context performs a version of the same trick by gentler means. A humble dish eaten on holiday, at a wedding, or after a long day's walking, is very often recalled for years — not because the cooking was extraordinary in any way a judge could score, but because the company and the circumstance had already primed the mind to receive it well, exactly as a white plate primes the mind to taste sweetness, or a printed price primes the mind to taste quality. Brillat-Savarin, whose aphorisms have accompanied this chapter from its epigraph onward, understood this collaborative quality of pleasure better than any gastronome before or since. "The pleasure of the table," he wrote, "belongs to all ages, to all conditions, to all countries, and to all areas; it mingles with all other pleasures, and remains at last to console us for their departure."[^13] It is a claim that could sound, from a lesser writer, like mere sentiment. From the author of the Physiologie du Goût, who had spent an entire book demonstrating that taste is inseparable from company, memory, and circumstance, it reads instead as a plain statement of observed fact: the table is democratic in a way almost nothing else is, open to the poor as freely as to the rich, requiring nothing more than appetite and companionship to be enjoyed — and, because it draws so heavily on memory, as we have seen in the case of the madeleine, capable of being enjoyed twice: once at the time, and once again, indefinitely, in recollection.

Deliciousness reconsidered

We are now in a position to state plainly what this whole volume has been quietly building toward. Deliciousness, the reader may have assumed at the outset, is a property of food — fixed, measurable, waiting in the dish to be discovered by whichever tongue arrives first, rather as a note is either in tune or is not. It is nothing of the kind. Every chapter of this book has, in its own way, been dismantling that assumption: the tongue detects only five true tastes and leaves the rest of what we call flavour to the nose; the nose is itself a chemist working chiefly in retrospect, most of its labour performed only once food is already in the mouth; the trigeminal nerve cannot distinguish a real burn from a borrowed one; and now, finally, the very colour of a plate or the number printed on a wine list turns out to reach in and adjust the volume on sweetness itself, before any of the preceding machinery has had its say. It is a negotiation, conducted anew at every meal, between a world of molecules — sugars and acids, aroma compounds and capsaicinoids, the crackle of a crust and the weight of a spoon — and a mind that arrives at the table already primed by memory, expectation, hunger, colour, price, sound, and company, ready to meet those molecules rather more than halfway. Change the mind's contribution — dim the lights, dye the wine, weight the spoon, print a higher number on the label, fill the room with the roar of a jet engine, or simply arrive very hungry — and the very same plate of food becomes, quite genuinely, a different dish, not through any trick played upon a passive taster but through the ordinary and continuous work the mind performs at every meal, tasted or not. This is not a flaw in our perception, a smudge on an otherwise objective instrument. It is how the instrument was built. The tongue and nose supply the raw material; the mind, hungrily and unstoppably, finishes the meal.

We began this volume with the humble apple and the small orchestra it performs in a single bite; we close this chapter with the discovery that the conductor of that orchestra was never on the tongue at all, but seated somewhere behind the eyes, reading the room, consulting old memories, weighing the spoon, and quietly setting the tempo before the first note ever sounds. Taste, aroma, texture, chemesthesis, and now the mind's own restless contribution: every instrument this compendium has catalogued has, at last, been introduced to the reader. What remains is to hear them play together — to see how a great cook, or a great cuisine, takes this whole unruly orchestra and, mouthful by considered mouthful, brings it into balance.

[^1]: Cheskin coined the term sensation transference while consulting for American food and consumer-goods manufacturers in the 1930s and 1940s; his work predates, and in many respects anticipates, the modern discipline of gastrophysics by some seventy years. [^2]: Piqueras-Fiszman, B., & Spence, C. (2012). "Assessing the influence of the colour of the plate on the perception of a complex food in a restaurant setting." Flavour, 1:24. [^3]: Morrot, G., Brochet, F., & Dubourdieu, D. (2001). "The Color of Odors." Brain and Language, 79, 309–320. [^4]: Plassmann, H., O'Doherty, J., Shiv, B., & Rangel, A. (2008). "Marketing actions can modulate neural representations of experienced pleasantness." Proceedings of the National Academy of Sciences, 105(3), 1050–1054. [^5]: Harrar, V., & Spence, C. (2013). "The taste of cutlery: how the taste of food is affected by the weight, size, shape, and colour of the cutlery used to eat it." Flavour, 2:21. [^6]: See, more broadly, Spence, C. (2017). Gastrophysics: The New Science of Eating, which surveys the wider evidence that heavier plates, glassware and packaging generally raise perceived quality and willingness to pay, the cutlery study above being an instructive exception that proves the rule is really about expectation rather than mass alone. [^7]: Zampini, M., & Spence, C. (2004). "The Role of Auditory Cues in Modulating the Perceived Crispness and Staleness of Potato Chips." Journal of Sensory Studies, 19, 347–363. [^8]: Yan, K. S., & Dando, R. (2015). "A crossmodal role for audition in taste perception." Journal of Experimental Psychology: Human Perception and Performance, 41(3), 590–596. [^9]: The Fraunhofer Institute for Building Physics study was commissioned by Lufthansa and released in 2010; it was an industry-sponsored investigation rather than an independently peer-reviewed paper, and is best read as suggestive corroboration of the later Cornell laboratory findings rather than as equivalent evidence in its own right. [^10]: Rolls, B. J., Rolls, E. T., Rowe, E. A., & Sweeney, K. (1981). "Sensory specific satiety in man." Physiology & Behavior, 27, 137–142. [^11]: The shared compound is trimethylamine; the anecdote is widely reported in accounts of the founding of the Foodpairing method developed by Bernard Lahousse, François Benzi and Heston Blumenthal. [^12]: Ahn, Y.-Y., Ahnert, S. E., Bagrow, J. P., & Barabási, A.-L. (2011). "Flavor network and the principles of food pairing." Scientific Reports, 1, 196. [^13]: Brillat-Savarin, J. A. Physiologie du Goût, Aphorism VII, 1825.

บทถัดไป · 11 / 16Chapter 8 — Balance & the Composed Mouthful