Chrono Compendium
Zenan Plains - Site Discussion => General Discussion => Topic started by: ZeaLitY on February 08, 2011, 12:10:40 am
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This link is so interesting that I'm making its own thread:
http://www.edge.org/q2011/q11_index.html
A ton of scientists were asked this very question, and offered a lot of fascinating ideas. It all starts on page one:
http://www.edge.org/q2011/q11_2.html
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Purtty interestin! *bookmarks*
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Ugh... over 150 authors. Someone should take one for the team and go through them all, making a list of the authors that are really worth reading.
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I'm going to collect my favorites and post them here.
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One a day. Discussion welcome and invited. First one:
DONALD HOFFMAN
Cognitive Scientist, UC, Irvine; Author, Visual Intelligence
Sensory Desktop
Our perceptions are neither true nor false. Instead, our perceptions of space and time and objects, the fragrance of a rose, the tartness of a lemon, are all a part of our "sensory desktop," which functions much like a computer desktop.
Graphical desktops for personal computers have existed for about three decades. Yet they are now such an integral part of daily life that we might easily overlook a useful concept that they embody. A graphical desktop is a guide to adaptive behavior. Computers are notoriously complex devices, more complex than most of us care to learn. The colors, shapes and locations of icons on a desktop shield us from the computer's complexity, and yet they allow us to harness its power by appropriately informing our behaviors, such as mouse movements and button clicks, that open, delete and otherwise manipulate files. In this way, a graphical desktop is a guide to adaptive behavior.
Graphical desktops make it easier to grasp the idea that guiding adaptive behavior is different than reporting truth. A red icon on a desktop does not report the true color of the file it represents. Indeed, a file has no color. Instead, the red color guides adaptive behavior, perhaps by signaling the relative importance or recent updating of the file. The graphical desktop guides useful behavior, and hides what is true but not useful. The complex truth about the computer's logic gates and magnetic fields is, for the purposes of most users, of no use.
Graphical desktops thus make it easier to grasp the nontrivial difference between utility and truth. Utility drives evolution by natural selection. Grasping the distinction between utility and truth is therefore critical to understanding a major force that shapes our bodies, minds and sensory experiences.
Consider, for instance, facial attractiveness. When we glance at a face we get an immediate feeling of its attractiveness, a feeling that usually falls somewhere between hot and not. That feeling can inspire poetry, evoke disgust, or launch a thousand ships. It certainly influences dating and mating. Research in evolutionary psychology suggests that this feeling of attractiveness is a guide to adaptive behavior. The behavior is mating, and the initial feeling of attractiveness towards a person is an adaptive guide because it correlates with the likelihood that mating with that person will lead to successful offspring.
Just as red does not report the true color of a file, so hotness does not report the true feeling of attractiveness of a face: Files have no intrinsic color, faces have no intrinsic feeling of attractiveness. The color of an icon is an artificial convention to represent aspects of the utility of a colorless file. The initial feeling of attractiveness is an artificial convention to represent mate utility.
The phenomenon of synesthesia can help to understand the conventional nature of our sensory experiences. In many cases of synesthesia, a stimulus that is normally experienced in one way, say as a sound, is also automatically experienced in another way, say as a color. Someone with sound-color synesthesia sees colors and simple shapes whenever they hear a sound. The same sound always occurs with the same colors and shapes. Someone with taste-touch synesthesia feels touch sensations in their hands every time they taste something with their mouth. The same taste always occurs with the same feeling of touch in their hands. The particular connections between sound and color that one sound-color synesthete experiences typically differ from the connections experienced by another such synesthete. In this sense, the connections are an arbitrary convention. Now imagine a sound-color synesthete who no longer has sound experiences to acoustic stimuli, and instead has only their synesthetic color experiences. Then this synesthete would only experience as colors what the rest of us experience as sounds. In principle they could get all the acoustic information the rest of us get, only in a color format rather than a sound format.
This leads to the concept of a sensory desktop. Our sensory experiences, such as vision, sound, taste and touch, can all be thought of as sensory desktops that have evolved to guide adaptive behavior, not to report objective truths. As a result, we should take our sensory experiences seriously. If something tastes putrid, we probably shouldn't eat it. If it sounds like a rattlesnake, we probably should avoid it. Our sensory experiences have been shaped by natural selection to guide such adaptive behaviors.
We must take our sensory experiences seriously, but not literally. This is one place where the concept of a sensory desktop is helpful. We take the icons on a graphical desktop seriously; we won't, for instance, carelessly drag an icon to the trash, for fear of losing a valuable file. But we don't take the colors, shapes or locations of the icons literally. They are not there to resemble the truth. They are there to facilitate useful behaviors.
Sensory desktops differ across species. A face that could launch a thousand ships probably has no attraction to a macaque monkey. The rotting carrion that tastes putrid to me might taste like a delicacy to a vulture. My taste experience guides behaviors appropriate for me: Eating rotten carrion could kill me. The vulture's taste experience guides behaviors appropriate to it: Carrion is its primary food source.
Much of evolution by natural selection can be understood as an arms race between competing sensory desktops. Mimicry and camouflage exploit limitations in the sensory desktops of predators and prey. A mutation that alters a sensory desktop to reduce such exploitation conveys a selective advantage. This cycle of exploiting and revising sensory desktops is a creative engine of evolution.
On a personal level, the concept of a sensory desktop can enhance our cognitive toolkit by refining our attitude towards our own perceptions. It is common to assume that the way I see the world is, at least in part, the way it really is. Because, for instance, I experience a world of space and time and objects, it is common to assume that these experiences are, or at least resemble, objective truths. The concept of a sensory desktop reframes all this. It loosens the grip of sensory experiences on the imagination. Space, time and objects might just be aspects of a sensory desktop that is specific to Homo sapiens. They might not be deep insights into objective truths, just convenient conventions that have evolved to allow us to survive in our niche. Our desktop is just a desktop.
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Creating an imaginary distinction between utility and truth goes against everything I believe in. The fact is, information has no utility if there is no truth to it. A more accurate distinction would be between truth that is useful and truth that is not. Other than that, this man is simply stating what is obvious: our senses are not 100% objective. I like to think that most people are already aware of this and adapt their modes of thinking to compensate for it the best they can.
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Actually, Squire, I think his main point was
DONALD HOFFMAN
On a personal level, the concept of a sensory desktop can enhance our cognitive toolkit by refining our attitude towards our own perceptions. It is common to assume that the way I see the world is, at least in part, the way it really is.
We see this quite often in the political and religious spheres where individuals cannot imagine that others might legitimately perceive the world differently than they do. Because individuals see their own perception as reflective of truth, opposing perceptions must therefore be not-reflective of truth and therefore vile.
To be fair, Hoffman seems a little taken by his own metaphor and conflates descriptors as truths (computer files aside, to call a red ball red isn't a statement of truth but rather of fact), but there is at least a kernel of usefulness in his statements.
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DANIEL KAHNEMAN
Psychologist, Princeton; Recipient, 2002 Nobel Prize in Economic Sciences
Focusing Illusion
"Nothing In Life Is As Important As You Think It Is, While You Are Thinking About It"
Education is an important determinant of income — one of the most important — but it is less important than most people think. If everyone had the same education, the inequality of income would be reduced by less than 10%. When you focus on education you neglect the myriad other factors that determine income. The differences of income among people who have the same education are huge.
Income is an important determinant of people's satisfaction with their lives, but it is far less important than most people think. If everyone had the same income, the differences among people in life satisfaction would be reduced by less than 5%.
Income is even less important as a determinant of emotional happiness. Winning the lottery is a happy event, but the elation does not last. On average, individuals with high income are in a better mood than people with lower income, but the difference is about 1/3 as large as most people expect. When you think of rich and poor people, your thoughts are inevitably focused on circumstances in which their income is important. But happiness depends on other factors more than it depends on income.
Paraplegics are often unhappy, but they are not unhappy all the time because they spend most of the time experiencing and thinking about other things than their disability. When we think of what it is like to be a paraplegic, or blind, or a lottery winner, or a resident of California we focus on the distinctive aspects of each of these conditions. The mismatch in the allocation of attention between thinking about a life condition and actually living it is the cause of the focusing illusion.
Marketers exploit the focusing illusion. When people are induced to believe that they "must have" a good, they greatly exaggerate the difference that the good will make to the quality of their life. The focusing illusion is greater for some goods than for others, depending on the extent to which the goods attract continued attention over time. The focusing illusion is likely to be more significant for leather car seats than for books on tape.
Politicians are almost as good as marketers in causing people to exaggerate the importance of issues on which their attention is focused. People can be made to believe that school uniforms will significantly improve educational outcomes, or that health care reform will hugely change the quality of life in the United States — either for the better or for the worse. Health care reform will make a difference, but the difference will be smaller than it appears when you focus on it.
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Well now, this person makes a few interesting claims that I would love to see backed up with some data. In particular, the claims that involve a percentage or proportion. But I don't want to know badly enough to go digging through a bunch of research papers to find it. I find myself wanting to believe it... which leads me to suspect there may be a bias in the sampling of data.
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This is awesome and quite enlightening! Hurray!
Creating an imaginary distinction between utility and truth goes against everything I believe in. The fact is, information has no utility if there is no truth to it. A more accurate distinction would be between truth that is useful and truth that is not. Other than that, this man is simply stating what is obvious: our senses are not 100% objective. I like to think that most people are already aware of this and adapt their modes of thinking to compensate for it the best they can.
I would suggest that his major point is more along the lines of well, objectivity is extremely complex and we are experiencing it in certain ways that are useful for us than our senses are faulty, however. The whole notion of a mind/body or mind/world division is outdated; we're not just passive observers who sometimes get it right and sometimes don't. He deliberately avoids framing the question in terms of truth vs untruth.
Income is even less important as a determinant of emotional happiness. Winning the lottery is a happy event, but the elation does not last. On average, individuals with high income are in a better mood than people with lower income, but the difference is about 1/3 as large as most people expect. When you think of rich and poor people, your thoughts are inevitably focused on circumstances in which their income is important. But happiness depends on other factors more than it depends on income.
I've seen a study that dovetails with this conclusion nicely. Basically, it was "money can't bring you happiness, but poverty sure can." The psychologist said that basically for families below 60,000, money did correlate with happiness, but after 60,000, it makes no difference at all. "I've never seen a line that straight," he said.
Interesting. I've seen things that contradict his statement about education, but it's good to hear a balancing opinion to the usual "education is essential" rhetoric.
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RICHARD THALER
The Father of Behavioral Economics; Director, Center for Decision Research at the University of Chicago Graduate School of Business; Coauthor, Nudge: Improving Decisions About Health, Wealth, and Happiness
Aether
I recently posted a question in this space asking people to name their favorite example of a wrong scientific belief. One of my favorite answers came from Clay Shirky. Here is an excerpt:
"The existence of ether, the medium through which light (was thought to) travel. It was believed to be true by analogy — waves propagate through water, and sound waves propagate through air, so light must propagate through X, and the name of this particular X was ether."
It's also my favorite because it illustrates how hard it is to accumulate evidence for deciding something doesn't exist. Ether was both required by 19th century theories and undetectable by 19th century apparatus, so it accumulated a raft of negative characteristics: it was odorless, colorless, inert, and so on.
Several other entries (such as the "force of gravity") shared the primary function of ether: they were convenient fictions that were able to "explain" some otherwise ornery facts. Consider this quote from Max Pettenkofer, the German chemist and physician, is disputing the role of bacteria as a cause of the cholera. "Germs are of no account in cholera! The important thing is the disposition of the individual."
So in answer to the current question I am proposing that we now change the usage of the word Aether, using the old spelling, since there is no need for a term that refers to something that does not exist. Instead, I suggest we use that term to describe the role of any free parameter used in a similar way: that is, Aether is the thing that makes my theory work. Replace the word disposition with Aether in Pettenkofer's sentence above to see how it works.
Often Aetherists (theorists who rely on an Aether variable) think that their use of the Aether concept renders the theory untestable. This belief is often justified during their lifetimes, but then along comes clever empiricists such as Michelson and Morley and last year's tautology become this year's example of a wrong theory.
Aether variables are extremely common in my own field of economics. Utility is the thing you must be maximizing in order to render your choice rational.
Both risk and risk aversion are concepts that were once well defined, but are now in danger of becoming Aetherized. Stocks that earn surprisingly high returns are labeled as risky, because in the theory, excess returns must be accompanied by higher risk. If, inconveniently, the traditional measures of risk such as variance or covariance with the market are not high, then the Aetherists tell us there must be some other risk; we just don't know what it is.
Similarly, traditionally the concept of risk aversion was taken to be a primitive; each person had a parameter, gamma, that measured her degree of risk aversion. Now risk aversion is allowed to be time varying, and Aetherists can say with a straight face that the market crashes of 2001 and 2008 were caused by sudden increases in risk aversion. (Note the direction of the causation. Stocks fell because risk aversion spiked, not vice versa.)
So, the next time you are confronted with such a theory, I suggest substituting the word Aether for the offending concept. Personally, I am planning to refer to the time-varying variety of risk aversion as Aether aversion.
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I like this one.
I would also hypothesize that all aether variables make for excellent additions to the steampunk genre.
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BRIAN ENO
Artist; Composer; Recording Producer: U2, Cold Play, Talking Heads, Paul Simon; Recording Artist; Author, A Year With Swollen Appendices
Ecology
That idea, or bundle of ideas, seems to me the most important revolution in general thinking in the last 150 years. It has given us a whole new sense of who we are, where we fit, and how things work. It has made commonplace and intuitive a type of perception that used to be the province of mystics — the sense of wholeness and interconnectedness.
Beginning with Copernicus, our picture of a semi-divine humankind perfectly located at the centre of The Universe began to falter: we discovered that we live on a small planet circling a medium sized star at the edge of an average galaxy. And then, following Darwin, we stopped being able to locate ourselves at the centre of life. Darwin gave us a matrix upon which we could locate life in all its forms: and the shocking news was that we weren't at the centre of that either — just another species in the innumerable panoply of species, inseparably woven into the whole fabric (and not an indispensable part of it either). We have been cut down to size, but at the same time we have discovered ourselves to be part of the most unimaginably vast and beautiful drama called Life.
Before ''ecology'' we understood the world in the metaphor of a pyramid — a heirarchy with God at the top, Man a close second and, sharply separated, a vast mass of life and matter beneath. In that model, information and intelligence flowed in one direction only — from the intelligent top to the ''base'' bottom — and, as masters of the universe, we felt no misgivings exploiting the lower reaches of the pyramid.
The ecological vision has changed that: we now increasingly view life as a profoundly complex weblike system, with information running in all directions, and instead of a single heirarchy we see an infinity of nested-together and co-dependent heirarchies — and the complexity of all this is such to be in and of itself creative. We no longer need the idea of a superior intelligence outside of the system — the dense field of intersecting intelligences is fertile enough to account for all the incredible beauty of ''creation''.
The ''ecological'' view isn't confined to the organic world. Along with it comes a new understanding of how intelligence itself comes into being. The classical picture saw Great Men with Great Ideas...but now we tend to think more in terms of fertile circumstances where uncountable numbers of minds contribute to a river of innovation. It doesn't mean we cease to admire the most conspicuous of these — but that we understand them as effects as much as causes. This has ramifications for the way we think about societal design, about crime and conflict, education, culture and science.
That in turn leads to a re-evaluation of the various actors in the human drama. When we realise that the cleaners and the bus drivers and the primary school teachers are as much a part of the story as the professors and the celebrities, we will start to accord them the respect they deserve.
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RICHARD DAWKINS
Evolutionary Zoologist, University of Oxford. Author, The Blind Watchmaker; The Greatest Show on Earth
The Double-Blind Control Experiment
Not all concepts wielded by professional scientists would improve everybody's cognitive toolkit. We are here not looking for tools with which research scientists might benefit their science. We are looking for tools to help non-scientists understand science better, and equip them to make better judgments throughout their lives.
Why do half of all Americans believe in ghosts, three quarters believe in angels, a third believe in astrology, three quarters believe in Hell? Why do a quarter of all Americans and believe that the President of the United States was born outside the country and is therefore ineligible to be President? Why do more than 40 percent of Americans think the universe began after the domestication of the dog?
Let's not give the defeatist answer and blame it all on stupidity. That's probably part of the story, but let's be optimistic and concentrate on something remediable: lack of training in how to think critically, and how to discount personal opinion, prejudice and anecdote, in favour of evidence. I believe that the double-blind control experiment does double duty. It is more than just an excellent research tool. It also has educational, didactic value in teaching people how to think critically. My thesis is that you needn't actually do double-blind control experiments in order to experience an improvement in your cognitive toolkit. You only need to understand the principle, grasp why it is necessary, and revel in its elegance.
If all schools taught their pupils how to do a double-blind control experiment, our cognitive toolkits would be improved in the following ways:
1. We would learn not to generalise from anecdotes.
2. We would learn how to assess the likelihood that an apparently important effect might have happened by chance alone.
3. We would learn how extremely difficult it is to eliminate subjective bias, and that subjective bias does not imply dishonesty or venality of any kind. This lesson goes deeper. It has the salutary effect of undermining respect for authority, and respect for personal opinion.
4. We would learn not to be seduced by homeopaths and other quacks and charlatans, who would consequently be put out of business.
5. We would learn critical and skeptical habits of thought more generally, which not only would improve our cognitive toolkit but might save the world.
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MARTIN REES
President Emeritus, The Royal Society; Professor of Cosmology & Astrophysics; Master, Trinity College, University of Cambridge; Author, Our Final Century: The 50/50 Threat to Humanity's Survival
"Deep Time" And The Far Future
We need to extend our time-horizons. Especially, we need deeper and wider awareness that far more time lies ahead than has elapsed up till now.
Our present biosphere is the outcome of more than four billion years of evolution; and we can trace cosmic history right back to a "big bang" that happened about 13.7 billion years ago. The stupendous time-spans of the evolutionary past are now part of common culture and understanding — even though the concept may not yet have percolated all parts of Kansas, and Alaska.
But the immense time-horizons that stretch ahead — though familiar to every astronomer — haven't permeated our culture to the same extent. Our Sun is less than half way through its life. It formed 4.5 billion years ago, but it's got 6 billion more before the fuel runs out. It will then flare up, engulfing the inner planets and vaporising any life that might then remain on Earth. But even after the Sun's demise, the expanding universe will continue — perhaps for ever — destined to become ever colder, ever emptier. That, at least, is the best long range forecast that cosmologists can offer, though few would lay firm odds on what may happen beyond a few tens of billions of years.
Awareness of the "deep time" lying ahead is still not pervasive. Indeed, most people — and not only those for whom this view is enshrined in religious beliefs —envisage humans as in some sense the culmination of evolution. But no astronomer could believe this; on the contrary, it would be equally plausible to surmise that we are not even at the halfway stage. There is abundant time for posthuman evolution, here on Earth or far beyond, organic or inorganic, to give rise to far more diversity, and even greater qualitative changes, than those that have led from single-celled organisms to humans. Indeed this conclusion is strengthened when we realise that future evolution will proceed not on the million-year timescale characteristic of Darwinian selection, but at the much accelerated rate allowed by genetic modification and the advance of machine intelligence (and forced by the drastic environmental pressures that would confront any humans who were to construct habitats beyond the Earth.
Darwin himself realised that "No living species will preserve its unaltered likeness into a distant futurity". We now know that "futurity" extends far further, and alterations can occur far faster — than Darwin envisioned. And we know that the cosmos, through which life could spread, is far more extensive and varied than he envisaged. So humans are surely not the terminal branch of an evolutionary tree, but a species that emerged early in cosmic history, with special promise for diverse evolution. But this is not to diminish their status. We humans are entitled to feel uniquely important as the first known species with the power to mould its evolutionary legacy.
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MAHZARIN R. BANAJI
Richard Clarke Cabot Professor of Social Ethics, Department of Psychology, Harvard University
A Solution for Collapsed Thinking: Signal Detection Theory
We perceive the world through our senses. The brain-mediated data we receive in this way form the basis of our understanding of the world. From this become possible the ordinary and exceptional mental activities of attending, perceiving, remembering, feeling, and reasoning. Via these mental processes we understand and act on the material and social world.
In the town of Pondicherry in South India, where I sit as I write this, many do not share this assessment. There are those, including some close to me, who believe there are extrasensory paths to knowing the world that transcend the five senses, that untested "natural" foods and methods of acquiring information are superior to those based in evidence. On this trip, for example, I learned that they believe that a man has been able to stay alive without and caloric intake for months (although his weight falls, but only when he is under scientific observation).
Pondicherry is an Indian Union Territory that was controlled by the French for 300 years (staving off the British in many a battle right outside my window) and held on to until a few years after Indian independence. It has, in addition to numerous other points of attraction, become a center for those who yearn for spiritual experience, attracting many (both whites and natives) to give up their worldly lives to pursue the advancement of the spirit, to undertake bodily healing, and to invest in good works on behalf of a larger community.
Yesterday, I met a brilliant young man who had worked as a lawyer for eight years who now lives in the ashram and works in their book sales division. Sure, you retort, the profession of the law would turn any good person toward spirituality but I assure you that that the folks here have given up wealth and professional life of a wide variety of sorts to pursue this manner of life. The point is that seemingly intelligent people seem to crave non-rational modes of thinking and the Edge question this years forced me to think not only about the toolkit of the scientist but every person.
I do not mean to pick on any one city, and certainly not this unusual one in which so much good effort is put towards the arts and culture and on social upliftment of the sort we would admire. But this is a town that also attracts a particular type of European, American, and Indian — those whose minds seem more naturally prepared to believe that unprocessed "natural" herbs do cure cancer and that standard medical care is to be avoided (until one desperately needs chemo), that Tuesdays are inauspicious for starting new projects, that particular points in the big toe control the digestive system, that the position of the stars at the time of their birth led them to Pondicherry through an inexplicable process emanating from a higher authority and through a vision from "the mother", a deceased French woman, who dominates the ashram and surrounding area in death more than many successful politicians ever do in their entire lives.
These types of beliefs may seem extreme but they are not considered as such in most of the world. Change the content and the underlying false manner of thinking is readily observed just about anywhere — the new 22 inches of snow that has fallen where I live in the United States while I'm away will no doubt bring forth beliefs of a god angered by crazy scientists toting global warming.
As I contemplate the single most powerful tool that could be put into the heads of every growing child and every adult seeking a rational path, scientists included, it is the simple and powerful concept of "signal detection". In fact, the Edge question this year happens to be one I've contemplated for a while — should anybody ever ask such a question, the answer I've known would be an easy one: I use Green & Swets Signal detection theory and Psychophysics as the prototype, although the idea has its origins in earlier work among scientists concerned with the fluctuations of photons and their influence on visual detection and sound waves and their influence on audition.
The idea underlying the power of signal detection theory is simple: The world gives noisy data, never pure. Auditory data, for instance, are degraded for a variety of reasons having to do with the physical properties of the communication of sound. The observing organism has properties that further affect how those data will be experienced and interpreted, such as ability (e.g., a person's auditory acuity), the circumstances under which the information is being processed (e.g., during a thunderstorm), and motivation (e.g., disinterest). Signal detection theory allows us to put both aspects of the stimulus and the respondent together to understand the quality of the decision that will result given the uncertain conditions under which data are transmitted, both physically and psychologically.
To understand the crux of signal detection theory, each event of any data impinging on the receiver (human or other) is coded into four categories, providing a language to describe the decision:
Did the event occur?
Yes No
Yes Hit False Alarm
Did the received detect it?
No Miss Correct Rejection
Hit: A signal is present and the signal is detected (correct response)
False Alarm: No signal is presented but a signal is detected (incorrect response)
Miss: A signal is present but no signal is detected (incorrect response)
Correct Rejection: No signal is present and no signal is detected (correct response)
If the signal is clear, like a bright light against a dark background, the decision maker has good visual acuity and is motivated to watch for the signal, we should see a large number of Hits and Correct Rejections and very few False Alarms and Misses. As these properties change, so does the quality of the decision. Whether the stimulus is a physical one like a light or sound, or a piece of information requiring an assessment about its truth, information is almost always deviates from goodness.
It is under such ordinary conditions of uncertainty that signal detection theory yields a powerful way to assess the stimulus and respondent qualities including the respondent's idiosyncratic criterion (or cutting score, "c") for decision-making. The criterion is the place along the distribution at which point the respondent switches from the saying "no" to a "yes".
The applications of signal detection theory have been in areas as diverse as locating objects by sonar, the quality of remembering, the comprehension of language, visual perception, consumer marketing, jury decisions, price predictions in financial markets, and medical diagnoses.
The reason signal detection theory should be in the toolkit of every scientist is because it provides a mathematically rigorous framework to understand the nature of decision processes. The reason its logic should be in the toolkit of every thinking person is because it forces a completion of the four cells when analyzing the quality of any statement such as "Good management positions await Saggitarius this week".
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NIGEL GOLDENFELD
Professor of Physics, University of Illinois at Urbana-Champaign
Because
When you are facing in the wrong direction, progress means walking backwards. History suggests that our world view undergoes disruptive change not so much when science adds new concepts to our cognitive toolkit, but when it takes away old ones. The sets of intuitions that have been with us since birth define our scientific prejudices, and not only are poorly-suited to the realms of the very large and very small, but also fail to describe everyday phenomena. If we are to identify where the next transformation of our world view will come from, we need to take a fresh look at our deep intuitions. In the two minutes that it takes you to read this essay, I am going to try and rewire your basic thinking about causality.
Causality is usually understood as meaning that there is a single, preceding cause for an event. For example in classical physics, a ball may be flying through the air, because of having been hit by a tennis racket. My 16 year-old car always revs much too fast, because the temperature sensor wrongly indicates that the engine temperature is cold, as if the car was in start-up mode. We are so familiar with causality as an underlying feature of reality that we hard-wire it into the laws of physics. It might seem that this would be unnecessary, but it turns out that the laws of physics do not distinguish between time going backwards and time going forwards. And so we make a choice about which sort of physical law we would like to have.
However, complex systems, such as financial markets or the Earth's biosphere, do not seem to obey causality. For every event that occurs, there are a multitude of possible causes, and the extent to which each contributes to the event is not clear, not even after the fact! One might say that there is a web of causation. For example, on a typical day, the stock market might go up or down by some fraction of a percentage point. The Wall Street Journal might blithely report that the stock market move was due to "traders taking profits" or perhaps "bargain-hunting by investors". The following day, the move might be in the opposite direction, and a different, perhaps contradictory, cause will be invoked. However, for each transaction, there is both a buyer and a seller, and their world views must be opposite for the transaction to occur. Markets work only because there is a plurality of views. To assign single or dominant cause to most market moves is to ignore the multitude of market outlooks and to fail to recognize the nature and dynamics of the temporary imbalances between the numbers of traders who hold these differing views.
Similar misconceptions abound elsewhere in public debate and the sciences. For example, are there single causes for diseases? In some cases, such as Huntingdon's disease, the cause can be traced to a unique factor, in this case extra repetitions of a particular nucleotide sequence at a particular location in an individual's DNA, coding for the amino acid glutamine. However, even in this case, the age of onset and the severity of the condition are also known to be controlled by environmental factors and interactions with other genes. The web of causation has been for many decades a well-worked metaphor in epidemiology, but there is still little quantitative understanding of how the web functions or forms. As Krieger poignantly asked in a celebrated 1994 essay, "Has anyone seen the spider?"
The search for causal structure is nowhere more futile than in the debate over the origin of organismal complexity: intelligent design vs. evolution. Fueling the debate is a fundamental notion of causality, that there is a beginning to life, and that such a beginning must have had a single cause. On the other hand, if there is instead a web of causation driving the origin and evolution of life, a skeptic might ask: has anyone seen the spider?
It turns out that there is no spider. Webs of causation can form spontaneously through the concatenation of associations between the agents or active elements in the system. For example, consider the Internet. Although a unified protocol for communication (TCP/IP etc) exists, the topology and structure of the Internet emerged during a frenzied build-out, as Internet service providers staked out territory in a gold-rush of unprecedented scale. Remarkably, once the dust began to settle, it became apparent that the statistical properties of the resulting Internet were quite special: the time delays for packet transmission, the network topology, and even the information transmitted exhibit fractal properties.
However, you look at the Internet, locally or globally, on short time scales or long, it looks exactly the same. Although the discovery of this fractal structure around 1995 was an unwelcome surprise, because standard traffic control algorithms as used by routers were designed assuming that all properties of the network dynamics would be random, the fractality is also broadly characteristic of biological networks. Without a master blueprint, the evolution of an Internet is subject to the same underlying statistical laws that govern biological evolution, and structure emerges spontaneously without the need for a controlling entity. Moreover, the resultant network can come to life in strange and unpredictable ways, obeying new laws whose origin cannot be traced to any one part of the network. The network behaves as a collective, not just the sum of parts, and to talk about causality is meaningless because the behavior is distributed in space and in time.
Between 2.42pm and 2.50pm on May 6 2010, the Dow-Jones Industrial Average experienced a rapid decline and subsequent rebound of nearly 600 points, an event of unprecedented magnitude and brevity. This disruption occurred as part of a tumultuous event on that day now known as the Flash Crash, which affected numerous market indices and individual stocks, even causing some stocks to be priced at unbelievable levels (e.g. Accenture was at one point priced at 1 cent).
With tick-by-tick data available for every trade, we can watch the crash unfold in slow motion, a film of a financial calamity. But the cause of the crash itself remains a mystery. The US Securities and Exchange Commission report on the flash crash was able to identify the trigger event (a $4 billion sale by a mutual fund), but could provide no detailed understanding of why this event caused the crash. The conditions that precipitate the crash were already embedded in the market's web of causation, a self-organized rapidly evolving structure created by the interplay of high frequency trading algorithms. The Flash Crash was the birth cry of a network coming to life, eerily reminiscent of Arthur C. Clarke's science fiction story "Dial F for Frankenstein", which begins "At 0150 GMT on December 1, 1975, every telephone in the world started to ring." I'm excited by the scientific challenge of understanding all this in detail, because … well, never mind. I guess I don't really know.
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GARY MARCUS
Cognitive Scientist, NYU; Author, Kluge: The Haphazard Evolution of the Human Mind
Cognitive Humility
Hamlet may have said that human beings are noble in reason and infinite in faculty, but in reality — as four decades of experiments in cognitive psychology have shown — our minds are very finite, and far from noble. Knowing the limits of our minds can help us to make better reasoners.
Almost all of those limits start with a peculiar fact about human memory: although we are pretty good at storing information in our brains, we are pretty poor at retrieving that information. We can recognize photos from our high school yearbooks decades later—yet still find it impossible to remember what we had for breakfast yesterday. Faulty memories have been known to lead to erroneous eyewitness testimony (and false imprisonment), to marital friction (in the form of overlooked anniversaries), and even death (skydivers, for example have been known to forget to pull their ripcords — accounting, by one estimate, for approximately 6% of skydiving fatalities).
Computer memory is much more better than human memory because early computer scientists discovered a trick that evolution never did: organizing information according by assigning every memory to a sort of master map, in which each bit of information that is to be stored is assigned a specific, uniquely identifiable location in the computer's memory vaults. Human beings, in contrast. appear to lack such master memory maps, and instead retrieve information in far more haphazard fashion, by using clues (or cues) to what it's looking for, rather than knowing in advance where in the brain a given memory lies.
In consequence, our memories cannot be searched as systematically or as reliably as those of us a computer (or internet database). Instead, human memories are deeply subject to context. Scuba divers, for example, are better at remembering the words they study underwater when they are tested underwater (relative to when they were a tested on land), even if the words have nothing to do with the sea.
Sometimes this sensitivity to context is useful. We are better able to remember what we know about cooking when we are in the kitchen than when we are skiing, and vice versa.
But it also comes at a cost: when we need to remember something in a situation other than the one in which it was stored, it's often hard to retrieve it. One of the biggest challenges in education, for example, is to get children to take what they learn in school and apply it to real world situations, in part because context-driven memory means that what is learned in school tends to stay in school.
Perhaps the most dire consequence is that human beings tend almost invariably to be better at remembering evidence that is consistent with their beliefs than evidence that might disconfirm them. When two people disagree, it is often because their prior beliefs lead them to remember (or focus on) different bits of evidence. To consider something well, of course, is to evaluate both sides of an argument, but unless we also go the extra mile of deliberately forcing ourselves to consider alternatives—not something that comes naturally—we are more prone to recalling evidence consistent with a proposition than inconsistent with it.
Overcoming this mental weakness, known as confirmation bias, is a lifelong struggle; recognizing that we all suffer from it is a important first step.To the extent that we can beware of this limitation in our brains, we can try to work around it, compensating for our in-born tendencies towards self-serving and biased recollections by disciplining ourselves to consider not just the data that might fit with our own beliefs, but also the data that might lead other people to have beliefs that differ from our own.
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ERIC WEINSTEIN
Mathematician and Economist; Principal, Natron Group
Kayfabe
The sophisticated "scientific concept" with the greatest potential to enhance human understanding may be argued to come not from the halls of academe, but rather from the unlikely research environment of professional wrestling.
Evolutionary biologists Richard Alexander and Robert Trivers have recently emphasized that it is deception rather than information that often plays the decisive role in systems of selective pressures. Yet most of our thinking continues to treat deception as something of a perturbation on the exchange of pure information, leaving us unprepared to contemplate a world in which fakery may reliably crowd out the genuine. In particular, humanity's future selective pressures appear likely to remain tied to economic theory which currently uses as its central construct a market model based on assumptions of perfect information.
If we are to take selection more seriously within humans, we may fairly ask what rigorous system would be capable of tying together an altered reality of layered falsehoods in which absolutely nothing can be assumed to be as it appears. Such a system, in continuous development for more than a century, is known to exist and now supports an intricate multi-billion dollar business empire of pure hokum. It is known to wrestling's insiders as "Kayfabe".
Because professional wrestling is a simulated sport, all competitors who face each other in the ring are actually close collaborators who must form a closed system (called "a promotion") sealed against outsiders. With external competitors generally excluded, antagonists are chosen from within the promotion and their ritualized battles are largely negotiated, choreographed, and rehearsed at a significantly decreased risk of injury or death. With outcomes predetermined under Kayfabe, betrayal in wrestling comes not from engaging in unsportsmanlike conduct, but by the surprise appearance of actual sporting behavior. Such unwelcome sportsmanship which "breaks Kayfabe" is called "shooting" to distinguish it from the expected scripted deception called "working".
Were Kayfabe to become part of our toolkit for the twenty-first century, we would undoubtedly have an easier time understanding a world in which investigative journalism seems to have vanished and bitter corporate rivals cooperate on everything from joint ventures to lobbying efforts. Perhaps confusing battles between "freshwater" Chicago macro economists and Ivy league "Saltwater" theorists could be best understood as happening within a single "orthodox promotion" given that both groups suffered no injury from failing (equally) to predict the recent financial crisis. The decades old battle in theoretical physics over bragging rights between the "string" and "loop" camps would seem to be an even more significant example within the hard sciences of a collaborative intra-promotion rivalry given the apparent failure of both groups to produce a quantum theory of gravity.
What makes Kayfabe remarkable is that it gives us potentially the most complete example of the general process by which a wide class of important endeavors transition from failed reality to successful fakery. While most modern sports enthusiasts are aware of wrestling's status as a pseudo sport, what few alive today remember is that it evolved out of a failed real sport (known as "catch" wrestling) which held its last honest title match early in the 20th century. Typical matches could last hours with no satisfying action, or end suddenly with crippling injuries to a promising athlete in whom much had been invested. This highlighted the close relationship between two paradoxical risks which define the category of activity which wrestling shares with other human spheres:
• A) Occasional but Extreme Peril for the participants.
• B) General: Monotony for both audience and participants.
Kayfabrication (the process of transition from reality towards Kayfabe) arises out of attempts to deliver a dependably engaging product for a mass audience while removing the unpredictable upheavals that imperil participants. As such Kayfabrication is a dependable feature of many of our most important systems which share the above two characteristics such as war, finance, love, politics and science.
Importantly, Kayfabe also seems to have discovered the limits of how much disbelief the human mind is capable of successfully suspending before fantasy and reality become fully conflated. Wrestling's system of lies has recently become so intricate that wrestlers have occasionally found themselves engaging in real life adultery following exactly behind the introduction of a fictitious adulterous plot twist in a Kayfabe back-story. Eventually, even Kayfabe itself became a victim of its own success as it grew to a level of deceit that could not be maintained when the wrestling world collided with outside regulators exercising oversight over major sporting events.
At the point Kayfabe was forced to own up to the fact that professional wrestling contained no sport whatsoever, it did more than avoid being regulated and taxed into oblivion. Wrestling discovered the unthinkable: its audience did not seem to require even a thin veneer of realism. Professional wrestling had come full circle to its honest origins by at last moving the responsibility for deception off of the shoulders of the performers and into the willing minds of the audience.
Kayfabe, it appears, is a dish best served client-side.
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Fascinating! He nails one of my principle objections to economic theory, namely that it is based on faulty assumptions.
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Stuart Firestein
Neuroscientist, Columbia Universtiy
The Name Game
Too often in science we operate under the principle that "to name it is to tame it", or so we think. One of the easiest mistakes, even among working scientists, is to believe that labeling something has somehow or another added to an explanation or understanding of it. Worse than that we use it all the time when we are teaching, leading students to believe that a phenomenon that is named is a phenomenon that is known, and that to know the name is to know the phenomenon. It's what I, and others, have called the nominal fallacy. In biology especially, we have labels for everything - from molecules to anatomical parts, to physiological functions, to organisms, to ideas or hypotheses. The nominal fallacy is the error of believing that the label carries explanatory information.
An instance of the nominal fallacy is most easily seen when the meaning or importance of a term or concept shrinks with knowledge. One example of this would be the word "instinct". Instinct refers to a set of behaviors whose actual cause we don't know or simply don't understand or have access to; and therefore we call them instinctual, inborn, innate. Often this is the end of the exploration of these behaviors, they are the nature part of the nature-nurture argument (a term that itself is likely a product of the nominal fallacy) and therefore can't be broken down or reduced any further. But experience has shown that this is rarely the truth. In one of the great examples of this, it was for quite some time thought that when chickens hatched and they immediately began pecking the ground for food, this behavior must have been instinctive. In the 1920s a Chinese researcher named Zing-Yang Kuo made a remarkable set of observations on the developing chick egg that overturned this idea — and many similar ones. Using a technique of elegant simplicity he found that rubbing heated Vaseline on a chicken egg caused it to become transparent enough to see the embryo inside without disturbing it. In this way he was able to make detailed observations of the development of the embryo from fertilization to hatching. One of his observations was that, in order for the growing embryo to fit properly in the egg, the neck is bent over the chest of the body in such a way that the head rests upon the chest just where the developing heart is encased. As the heart begins beating the head of the chicken is moved in an up-and-down manner that precisely mimics the movement that will be used later for pecking the ground. Thus the "innate" pecking behavior that the chicken appears to know miraculously upon birth has, in fact, been practiced for more than a week within the egg.
In medicine as well, physicians often find technical terms that lead patients to believe that more is known about pathology than may actually be the case. In Parkinson's patients we notice that they have an altered gait and in general that their movement's are slower. Physicians call this "bradykinesia", but it doesn't really tell you anymore than simply saying "they move slower".
Why do they move slower, what is the pathology and what is the mechanism for this slowed movement - these are the deeper questions hidden by the simple statement that "a cardinal symptom of Parkinson's is bradykinesia", satisfying though it might be to say the word to a patient's family.
In science the one critical issue is to be able to distinguish between what we know and what we don't know. This is often difficult enough as things that seem known, sometimes become unknown or at least more ambiguous. When is it time to quit doing an experiment because we now know something, when is it time to stop spending money and resources on a particular line of investigation because the facts are known? This line between the known and the unknown is already difficult enough to define, but the nominal fallacy often obscures it needlessly. Even words like gravity, which seems so well-settled, may lend more of an aura to the idea than it deserves. After all, the apparently very well settled ideas of Newtonian gravity were almost completely undone after 400 years by Einstein's General Relativity. And still today physicists do not have a clear understanding of what gravity is or where it comes from, even though it's effects can be described quite accurately.
Another facet of the nominal fallacy is the danger of using common words and giving them a scientific meaning. This has the often disastrous effect of leading an unwary public down a path of misunderstanding. Words like 'theory', 'law', 'force', do not mean in common discourse what they mean to a scientist. 'Success' in Darwinian evolution is not the same 'success' as taught by Dale Carnegie. Force to a physicist has a meaning quite different from that used in political discourse. The worst of these though may be "theory" and "law" which are almost polar opposites — theory being a strong idea in science while vague in common discourse, and law being a much more muscular social than scientific concept. These differences lead to sometimes serious misunderstandings between scientists and the public who supports their work.
Of course language is critical and we must have names for things to talk about them. But the power of language to direct thought should never be taken lightly and the dangers of the name game deserve our respect.
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BEATRICE GOLOMB. MD
Professor of Medicine, University of California, San Diego
The Dece(i)bo Effect
The Dece(i)bo Effect — think portmanteau of Deceive and Placebo — refers to the facile application of constructs, without unpackaging the concept and the assumptions on which it relies, in a fashion that, rather than benefiting thinking, leads reasoning astray.
Words and phrases enter common parlance, that capture a concept: Occam's razor, placebo, Hawthorne effect. Such phrases and code-words in principle facilitate discourse — and can indeed do so. Deploying the word or catchphrase adds efficiency to the interchange, by obviating the need for pesky review of the principles and assumptions encapsulated in the word.
Unfortunately, bypassing the need to articulate the conditions and assumptions on which validity of the construct rests, may lead to bypassing consideration of whether these conditions and assumptions legitimately apply. Use of the term can then, far from fostering sound discourse, serve to undermine it.
Take, for example, the "placebo," and "placebo effects." Unpackaging the terms, a "placebo" is in principle something that is physiologically "inert" — but believed by the recipient to be active, or possibly so. The term "placebo effect" refers to improvement of a condition when persons have been placed on a placebo, due to effects of expectation/suggestion.
With these terms well ensconced in the vernacular, Dece(i)bo Effects associated with them are much in evidence. Key presumptions regarding placebos and placebo effects are more typically wrong than not.
1. When hearing the word "placebo," scientists often presume "inert" - without stopping to ask: what is that allegedly physiologically inert substance? Indeed, even in principle, what could it be??
There isn't anything known to be physiologically inert. There are no regulations about what constitute placebos; and their composition — commonly determined by the manufacturer of the drug under study — is typically undisclosed. Among the uncommon cases where placebo composition has been noted, there are documented instances in which the placebo composition apparently produced spurious effects. Two studies used corn oil and olive oil placebos for cholesterol-lowering drugs: one noted that the "unexpectedly" low rate of heart attacks in the control group may have contributed to failure to see a benefit from the cholesterol drug. Another study noted "unexpected" benefit of a drug to gastrointestinal symptoms in cancer patients. But cancer patients bear increased likelihood of lactose intolerance — and the placebo was lactose, a "sugar pill." When the term "placebo" substitutes for actual ingredients, any thinking about how the composition of the control agent may have influenced the study is circumvented.
2. Because there are many settings in which persons with a problem, given placebo, report sizeable improvement on average when they are re-queried (see 3), many scientists have accepted that "placebo effects" — of suggestion — are both large in magnitude and widespread in the scope of what they benefit.
The Danish researcher Asbjørn Hróbjartsson conducted a systematic review of studies that compared a placebo to no treatment. He found that the placebo generally does: nothing. In most instances, there is no placebo effect. Mild "placebo effects" are seen, in the short term, for pain and anxiety. Placebo effects for pain are reported to be blocked by naloxone, an opiate antagonist — specifically implicating endogenous opiates in pain placebo effects, which would not be expected to benefit every possible outcome that might be measured.
3. When hearing that persons with a problem placed on a "placebo" report improvement, scientists commonly presume this must be due to the "placebo effect" - the effect of expectation/suggestion.
However, the effects are usually something else entirely. For instance: natural history of the disease, and regression to the mean. Consider a distribution, such as a bell-shape. Whether the outcome of interest is pain, blood pressure, cholesterol, or other, persons are classically selected for treatment if they are at one end of the distribution - say, the high end. But these outcomes are quantities that vary (for instance from physiological variation, natural history, measurement error...), and on average the high values will vary back down — a phenomenon termed "regression to the mean" that operates, placebo or no. (Hence, Hróbjartsson's findings.)
A different dece(i)bo problem beset Ted Kaptchuk's recent Harvard study in which researchers gave a "placebo," or nothing, to people afflicted with irritable bowel syndrome. They administered the placebo in a bottle boldly labeled "Placebo," and advised patients they were receiving placebos, which were known to be potent. The thesis was that one might harness the effects of expectation honestly, without deception, by telling subjects how powerful placebos in fact were - and by developing a close relationship with subjects. Researchers met repeatedly with subjects, gained subjects' appreciation for their concern and listening (as the researchers made clear), and repeatedly told subjects that placebos are powerful. Those placed on placebo obliged the researchers by telling them they had gotten better, moreso than those on nothing. The scientists attributed this to a placebo effect.
But what's to say patients weren't simply telling the scientists what they thought the scientists wished to hear? Such desire to please (a form, perhaps, of "social approval" reporting bias) had fertile grounds in which to operate and create what was interpreted as a placebo effect — which implies actual subjective benefit to symptoms. One wonders if so great an error of presumption would operate were there not an existing term, "placebo effect," to signify the interpretation the Harvard group chose.
Another explanation consistent with these results is specific physiological benefit. The study used a nonabsorbed fiber — microcrystalline cellulose — as the "Placebo" that subjects were told would be effective. The authors are applauded for disclosing its composition. But other nonabsorbed fibers benefit both constipation and diarrhea — symptoms of irritable bowel — and are prescribed for that purpose; psyllium is an example. Thus, specific physiological benefit of the "Placebo" to symptoms cannot be excluded.
Together these points illustrate that the term "placebo" cannot be presumed to imply "inert" (and generally does not); and that when studies see large benefit to symptoms in patients treated with "placebo" (expected from distribution considerations alone), one cannot infer these arose from large benefits of suggestion to symptoms (which evidence indicates may seldom operate).
Thus, rather than facilitating sound reasoning, evidence suggests that in many cases, including high stakes settings in which inferences may propagate to medical practice, substitution of a term — here, "placebo," "placebo effect" — for the concepts they are intended to convey, may actually thwart or bypass critical thinking about key issues, with implications to fundamental concerns for us all.
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BARRY C. SMITH
Director, Institute of Philosophy School of Advanced Study University of London; writer and presenter, BBC World Service series "The Mysteries of the Brain"
The Senses and the Multi-Sensory
For far too long we have laboured under a faulty conception of the senses. Ask anyone you know how many senses we have and they will probably say five; unless they start talking to you about a sixth sense. But why pick five? What of the sense of balance provided by the vestibular system, telling you whether you are going up or down in a lift, forwards or backwards on a train, or side to side on a boat? What about proprioception that gives you a firm sense of where your limbs are when you close your eyes? What about feeling pain, hot and cold? Are these just part of touch, like feeling velvet or silk? And why think of sensory experiences like seeing, hearing, tasting, touching and smelling as being produced by a single sense?
Contemporary neuroscientists have postulated two visual systems — one responsible for how things look to us, the other for controlling action — that operate independently of one another. The eye may fall for visual illusions but the hand does not, reaching smoothly for a shape that looks larger than it is to the observer.
And it doesn't stop here. There is good reason to think that we have two senses of smell: an external sense of smell, orthonasal olfaction, produced by inhaling, that enables us to detect things in the environment such food, predators or smoke; and internal sense, retronasal olfaction, produced by exhaling, that enables us to detect the quality of what we have just eaten, allowing us to decide whether we want any more or should expel it.
Associated with each sense of smell is a distinct hedonic response. Orthonasal olfaction gives rise to the pleasure of anticipation. Retronasal olfaction gives rise to the pleasure of reward. Anticipation is not always matched by reward. Have you ever noticed how the enticing aromas of freshly brewed coffee are never quite matched by the taste? There is always a little disappointment. Interestingly, the one food where the intensity of orthonsally and retronasally judged aromas match perfectly is chocolate. We get just what we expected, which may explain why chocolate is such a powerful stimulus.
Besides the proliferation of the senses in contemporary neuroscience, another major change is taking place. We used to study the senses in isolation, with the greatest majority of researchers focusing on vision. Things are rapidly changing. We now know that the senses do not operate in isolation, but combine at both early and late stages of processing to produce our rich perceptual experiences of our surroundings. It is almost never the case that our experience presents us with just sights or sounds. We are always enjoying conscious experiences made up of sights and sounds, smells, the feel of our body, the taste in our mouths; and yet these are not presented as separate sensory parcels. We simply take in the rich and complex scene without giving much thought to how the different contributors produce the whole experience.
We give little thought to how smell provides a background to every conscious waking moment. People who lose their sense of smell can be plunged into depression and show less sign of recovery a year later than people who lose their sight. This is because familiar places no longer smell the same, and people no longer have their reassuring olfactory signature. Also, patients who lose their smell believe they have lost their sense of taste. When tested, they acknowledge that that can taste sweet, sour, salt, bitter savoury, and metallic. But everything else, missing from the taste of what they are eating, is due to retronasal smell.
What we call taste is one of the most fascinating case studies for how inaccurate our view of our senses is: it is not produced by the tongue alone but is always an amalgam of taste, touch and smell. Touch contributes to sauces tasting creamy, and other foods tasting chewy, crisp, or stale. The only difference between potato chips, which "taste" fresh or stale, is a difference in texture. The largest part of what we call "taste" is in fact smell in the form of retronasal olfaction, which is why people who lose their ability to smell say they can no longer taste anything. Taste, touch and smell are not merely combined to produce experiences of foods of liquids, rather the information from the separate sensory channels is fused into a unified experience of that we call taste and food scientists call flavour.
Flavour perception is the result of multi-sensory integration of gustatory, olfactory and oral somatosenory information into a single experience whose components we are unable to distinguish. It is one of the most multi-sensory experiences we have and can be influenced by both sight and sound. The colours of wines and the sounds food make when we bite or chew them can have large impacts on our resulting appreciation and assessment, and irritation of the trigeminal nerve in the face will make chillies feel "hot" and menthol feel "cool" in the mouth without any actual change in temperature.
In sensory perception, multi-sensory integration is the rule not the exception. In audition, we don't just hear with our ears, we use our eyes to locate the apparent sources of sounds in the cinema where we "hear" the voices coming from the actors' mouths on the screen although the sounds are coming from the sides of the theatre. This is known as the ventriloquism effect. Similarly, retronasal odours detected by olfactory receptors in the nose are experienced as tastes in the mouth. The sensations get re-located to the mouth because oral sensations of chewing or swallowing capture our attention, making us think these olfactory experiences are occurring in the same place.
Other surprising collaboration among the senses are due to cross-modal effects, where stimulation of one sense boosts activity in another. Looking at someone's lips across a crowded room can improve our ability to hear what they are saying, and the smell of vanilla can make a liquid we sip "taste" sweeter, and less sour. This is why we say vanilla is sweet smelling, although sweet is a taste, and pure vanilla is not sweet at all. Industrial manufacturers know about these effects and exploit them. Certain aromas in shampoos, for example, can make the hair "feel" softer; and red coloured drinks "taste" sweet, while drinks with a light green colour "taste" sour. In many of these interactions vision will dominate; but not in every case
. For anyone unlucky enough to have disturbance in their vestibular system they will feel the world is spinning although cues from the eyes and the body should be telling them everything is still. Instead, the brain goes with the combined picture and vision and proprioception fall in line. Luckily, our senses cooperate and we get us around the world, and the world we inhabit is not a sensory, but a multisensory world.