For all those fake papers you've written
From the New Scientist technology blog (via Slashdot):
You may remember the story of some cheeky MIT students who wrote a computer programme to generate scientific papers. Well, now some researchers at the Indiana University School of Informatics have come up with an Inauthentic Paper Detector to foil it.
Mehmet Dalkilic, a data mining expert explains how it works: "We believe that there are subtle, short- and long-range word or even word string repetitions that exist in human texts, but not in many classes of computer-generated texts that can be used to discriminate based on meaning."
What is interesting is that these "subtle long-range repetitions" are definitely part of our comprehension of a text, but we don't necessarily have the confidence to claim a text is fake if it lacks them. We have the statistical sense innately that the computer in this program is making explicit.
It is one of the many ways that we help ourselves to make language more comprehensible -- a certain redundancy that keys the mind back to the subject at hand. A good writer uses those repeated phrases to make the text more understandable.
And it is one of the many reasons why natural texts have a relatively low information content, at least for their length -- they consistently follow certain patterns. For our minds, that's a good thing! It lets us understand them.
Intelligence in the age of the internet
CNET is running a series of articles on the kind of intelligence required for the world of changing technology. The first installment starts thusly:
Today, terabytes of easily accessed data, always-on Internet connectivity, and lightning-fast search engines are profoundly changing the way people gather information. But the age-old question remains: Is technology making us smarter? Or are we lazily reliant on computers, and, well, dumber than we used to be?
The article's answer is that different skills don't mean different reasoning and learning. Not unexpected, since business' focus in the wake of technological change is always training and retraining the same minds for different skillsets.
The main idea is how memory is less necessary when you have devices to keep track of things for you. I suppose if Sherlock Holmes' theory of mind is right, that means we should be able to fill up our minds with deeper thoughts:
"It's true we don't remember anything anymore, but we don't need to," said [Jeff] Hawkins, the co-founder of Palm Computing and author of a book called "On Intelligence."
"We might one day sit around and reminisce about having to remember phone numbers, but it's not a bad thing. It frees us up to think about other things. The brain has a limited capacity, if you give it high-level tools, it will work on high-level problems," he said.
Of course, this presupposes that the brain isn't full of cognitive adaptations that now lie fallow and useless in today's high-tech world. Or get filled with videogames and movies. I guess these fall under the Everything Bad Is Good for You theory.
I wonder what you would call a specialized cognitive adaptation that could be readily reprogrammed in different cultures for different purposes?
Money, status, and social cognition
Via Instapundit, a link to a review of the new book Freakonomics: A Rogue Economist Explores the Hidden Side of Everything. Looks like a very interesting book, covering topics ranging from why teachers and sumo wrestlers both cheat, to the economics of drug dealing.
On this latter subject, the review paraphrases the book's argument:
A chapter titled "Why Do Drug Dealers Still Live with Their Moms?" provides an analysis of the economic workings of a Chicago crack gang, based on data collected (initially at high personal risk) by a young sociologist named Sudhir Venkatesh. The upshot is that the crack trade, even at its market peak, was lucrative only for those at the top of a selling organization. The gang's foot soldiers made less than minimum wage and faced a 1-in-4 risk of being killed over four years. (In the same time, being a timber cutter, the most dangerous legitimate job in the U.S., carried a 1-in-200 risk.) These drug dealers struggled desperately to reach the gang's upper echelons, but few would make it.
From Instapundit:
My historian-brother often says that one of the most interesting phenomena that he's observed is the cross-cultural willingness of people to trade away economic benefits for status. I suspect that this is one example of that. So, in a surprisingly similar way, is being a politician. That's an obviously poor economic move for most folks. But one of the drug dealers in Price's book talks about how he likes the way he becomes the center of attention when he enters a room full of junkies. Politicians, I think, get the same thing, especially in the bubble-environments of Washington, or state capitals. I suspect, in fact, that people are, to varying degrees, hardwired to get an endorphin rush from that sort of attention, just as they're hardwired in varying degrees to respond to drugs.
As Reynold's readers comment, you can replace "crack" and "dealers" with "universities" and "professors" and come to a similar conclusion. People rarely maximize their monetary gains with their choice of careers or activities. After all, any of us could take an extra job at Taco Bell to turn our downtime into cash. If we were Scrooge McDuck-like packrats who did nothing but fill bank accounts, any extra dollar (or the employee burrito discount) would impel us. The fact is, people don't lust for money in this way. "The pursuit of happiness" is what most of us are spending most of our time planning, if not actually pursuing.
The thing that gets me is why anyone should expect that humans would be rational maximizers with respect to money, when money is a very recent cultural innovation. Status and prestige are much older influences on human behavior. Indeed, rank is a central component of many mammalian (even vertebrate!) social groups, and "status" is just another way of saying "rank" in human cultural terms. Determining rank must be an important part of the mental calculus of any social species, and humans if anything are beyond the capabilities of most. So there is every reason to think that humans should be adapted not to economic maximization, but instead to status enhancement -- mainly by seeking prestige from other people.
Sure, it is true that a lot of money can buy prestige and status of a certain kind. And if you just looove the feel of 1000-thread-count sheets and the looks you get when you drive an Astin-Martin, this kind of status may be exactly what you are looking for. But the pathways to status today are as varied as our lifestyles and interests. Consider the rewards that come with being the best-dressed Dr. Frank-N-Furter at the local Rocky Horror Picture Show revival. Or that comes along with the publication of an academic book. These things lead to prestige and status -- at least within a fairly loosely defined but circumscribed group of people -- but they certainly don't lead to economic benefit (when compared to the opportunity cost). Present-day human societies provide many channels for status-seeking, many of them non-overlapping. The effect is that most people can channel their activity into patterns that result in prestige-enhancement from some group of peers, at least sometime during their lives. And people for whom such courses are not available often face psychological consequences such as depression.
I think we can safely speculate that prehistoric human societies were the same as living ones in this respect. On one hand, population sizes and densities were smaller in the distant past, so that the same spectrum of options for prestige-seeking were certainly not available. That is to say, if your dream is to be a writer for the Dick Van Dyke Show and you live in Java around 200,000 BC, you're pretty much out of luck (unless you know Rose Marie's agent). But on the other hand, smaller population sizes mean fewer competitors for the range of behavioral specializations available. Less competition means more prestige for the same degree of talent, productivity, or knowledge.
Like societies in other primate species, such as chimpanzees, humans do not compete for status as a zero-sum game. Status is a product of a complex network of social interactions, and its cumulative effect is not easily predictable from the interactions themselves. This makes it a difficult calculation, and therefore leads to the hypothesis that our minds -- along with the minds of other social species -- possess special adaptations to perform such calculations. The adaptive value of such mental functions would be to shape decisions in a way that tends to increase status, and thereby fitness to the extent the two are correlated. Loosely put, this is the "social brain hypothesis," described by Robin Dunbar (1998; 2003).
There is, however, an important distinction to be made. The "social brain hypothesis" was proposed to explain brain size -- predicting that more social species will have larger brains for their body size.
[P]arsimony and biological common sense would suggest that it is group size that drives brain size evolution rather than brain size driving group size and that group size itself is a response to an ecological problem (most probably predation risk (van Schaik 1983, Dunbar 1988, Hill & Dunbar 1998)). Although the hypothesis has been tested by determining how neocortex volume constrains group size and other social indices, the evolutionary logic is that the need to maintain coherent groups of a particular size has driven neocortex volume evolution through its demands on cognitive competences. The most succinct and parsimonious causal sequence with fewest unsupported assumptions is that the window of opportunity provided for more intensely bonded social groups and the social skills that underpin this was the crucial selection pressure for the evolution of large brains, even though simple ecological pressures (e.g., the shift to a more frugivorous diet) may have been instrumental in kicking off the process. In these terms, any associated ecological skills may be seen as the outcome of the opportunity provided by an increase in general purpose intelligence generated off the back of the social requirements. To argue the reverse sequence (that large social groups are a by-product of having evolved large brains to solve simple ecological problems) is, as with the various ontogenetic hypotheses, to leave unanswered the problem of the costs of social living (Dunbar 2003:169).
If the relationship between social group size and brain size--or more specifically, neocortex size--could be quantified, then it would be possible to predict the group size of an extinct species based on the size of its brain. This is precisely what Dunbar has attempted for fossil hominids, and for living humans. Such an estimate for a population or species has become known as the "Dunbar number", and has found application in areas of the social sciences beyond animal behavior (most interestingly, in predicting characteristics of clandestine terrorist networks based on the kind of communication possible between the members).
This trend appears to hold across large taxonomic groups, like the primates. But within family level taxa, like the hominoids, it is unclear how much predictive power the hypothesis may have. In particular, the small social groups of orangutans appear to be a poor fit to the model when compared to their brains, which are similar in size to those of chimpanzees. So in the effort to predict characteristics of past species of hominids based on the size of their brains, the logic of the "social brain hypothesis" faces some perhaps insuperable problems.
I'm more interested in the aspects of mental flexibility and variability that arise as a consequence of selection for increased social tracking. As social groups grow in size, the number of binary interactions that any one individual needs to trace increases exponentially. The focus on this number of interactions is what drives the Dunbar model, along with the expectation that each of those interactions may require the investment of energy to maintain social status. But an increasing number of interactions is not the only change associated with larger social groups. We may also expect an increase in the number of kinds of interactions. This is a qualitative change that accompanies the quantitative change resulting from increasing population size.
Human evolution may or may not have seen the an increase in group size compared to our Miocene ancestors. Chimpanzee communities today number somewhat larger than human hunter-gatherer groups, on average. But chimpanzee committees themselves are comprised of smaller groups of individuals who may rarely see each other and the course of a month or longer. And human hunter-gatherers may coalesce into larger groups for social purposes. The complexity of social interactions within each of these species is beyond that of most other social species, factoring the variation in time spent with other individuals and the gradation of possible interactions from cooperation to aggression to reconciliation. Human evolution may not have seen an increase in group size, but it certainly saw an increase in the flexibility of interactions with individuals who were members of other groups. It also saw an increase in the degree of behavioral differentiation of individuals within groups. There were without doubt knowledge specialists for each of the components of ancient human cultures. This probably included specialists in tool manufacture, in hunting, in plant foraging, in midwifery, in negotiation with other groups, in knowledge of the landscape, and many other realms.
The possibility of specialists in different types of knowledge creates an "Information economy" in which people may attain and secure status on the basis of what they know about a specialized activity. If people can monopolize special information, then they can make themselves indispensable. And where different kinds of information are indispensable, different group members can leverage a more egalitarian social role.
To see this system in action, one need look no farther than the plot of any good story. Take for instance Homer's Iliad. In the descriptions of the war planning and decision-making, we see a very small subset of an ancient society--only the warrior class of ancient Greece. But even within this limited set, different individuals have different attributes that are essential to the enterprise. Agamemnon brings political power and finesse, Achilles brings martial skill and the intense loyalty of his followers, Odysseus brings clever planning and deceit, and Nestor brings a measured eye for tradition and restraint. Is it possible that in this microcosm of the story we can see the interactions within human social groups since the dawn of humanity? Clearly at the least it illustrates the ways that humans angle toward the unique role in their societies, that may defy ready quantification.
Returning to the issue of money, clearly economic advantage is one of the ways that we compete for social status today. Perhaps the majority of interactions that we have with other individuals have to do with the exchange of currency, or the social expectations that come from labor, consumerism, or other economic relations. And money even becomes part of our close social relationships, between family and friends. But few of us define ourselves in terms of money. Most people find other things that are more important to them. The discussion of money itself is something of a social taboo in our society, with most people considering it ill-mannered to directly raise the issue of how much someone makes, or how much they paid for something valuable. We play games of status around the issue of money, avoiding it almost whenever possible.
These games are an intricate result of our mental adaptations. The quest for social prestige and status is played on the field where the rules are fluid. Today's rules are different than those of the Stone Age, but the way we count our chits is mostly the same.
References:
Dunbar RIM. 1998. The social brain hypothesis. Evol Anthropol 6:178-190.
Dunbar RIM. 2003. The social brain: mind, language, and society in evolutionary perspective. Annu Rev Anthropol 32:163-181.
High-pressure performance and learned action sequences
The "Mind Matters" feature on the Scientific American blog has a commentary up by psychologist Sian Beilock. The commentary reviews last year's research that showed assigning a simple self-esteem-building essay can have a large impact on testing performance for minority students.
What I found much more interesting was Beilock's work on performance under pressure, when people are liable to "choke". I found a University of Chicago-sponsored description:
Her own experience as a lacrosse player at the University of California, San Diego, fueled Beilock's first questions about performance. To answer them, she retired her lacrosse stick and hit the putting green. Like riding a bike, Beilock says, putting becomes largely automatic once mastered, making it a "nice test bed" to gauge pressure's impact on golfers. When skilled players -- undergraduate subjects with two or more years of varsity golf experience or a PGA handicap lower than eight -- were asked to sink the ball while simultaneously identifying a specific word from a tape recording, putting ability came through unscathed, despite extra demands on concentration. Force these same experts, however, to think about their skill in a way they normally don't, such as focusing on club-swing distance or elbow position, and performance suffers. The extra attention, explains Beilock, is a common side effect of pressure situations that disrupts the flow of a well-honed activity, throwing off even the most talented individuals.
"Automatic" performance has long been fodder for intro psychology classes; it's a phenomenon that everybody can recognize. But there is a difference between the kind of automatic performance examined here -- a golf swing -- and automatic performance during other activities, like driving a car.
Driving is a long, continued activity that can occur with minimal conscious attention, at least in good conditions. But take a driver and distract him with a cell phone (or some kind of word-identifying task), and performance degrades.
So why don't the golfers experience the same performance degradation? The answer is that their "automatic" performance is in the form of highly practiced short action sequences. These short action sequences, by the way, are the kind of thing handled in the posterior part of Broca's area and the adjacent premotor cortex (link). The practiced actions do not degrade upon distraction, because the distraction does not interfere in any way with planning the sequence -- the sequence is already planned. But ask the golfer to "think about" his swing, and the sequence is brought back into question.
This kind of planned and practiced action sequence is fundamental to human imitation. If you can't parse a set of actions into some kind of sequence, you can't imitate it. This is the kind of imitation that other primates really aren't very good at. It's also probably fundamental to stone tool manufacture, since the fine control of knapping action depends on maintaining such short action sequences, and formulating longer strategies for segmenting them into a reduction sequence.
Other skills work in the opposite way. While a math whiz might perform calculations more quickly than a less-qualified classmate, successful execution still demands the expertâs dedicated focus. In contrast to a sensorimotor task like putting, many cognitive tasks call upon reserves of "working memory." It's the same type of short-term brain activity used to remember a number from the Yellow Pages long enough to make the call, and retention varies from person to person. In a low-stress situation -- Beilockâs subjects were told they were doing practice questions -- individuals who showed greater working-memory capacity did better on a challenging math task than lower-working-memory subjects. When pressure kicked in, however, these high-performers suffered the sharpest performance plunge. The discrepancy, Beilock says, suggests that individuals with high working memory may rely on complicated problem-solving techniques that naturally require more working-memory capacity than available under pressure. When anxiety begins to crowd that mental space, skilled individuals may not have enough room left over to solve the equation as quickly or successfully as usual.
Any of my students reading this after this week's exam should know that I sympathize!
This idea is very clever; I wonder if it isn't too clever. The hypothesis is that a larger working memory usually facilitiates a more complicated problem-solving method, which is more easily "crashed" by working memory "crowding". It's not obvious why stress should have this effect, though, which would seem to be highly maladaptive. Unless, "problem-solving" abilities evolved under a different context than "high-stress" situations. Maybe it is a very unusual strain of person who can think well under pressure -- or maybe an insensitivity to pressure is the real key?
Well, anyway, it seems clear that people really don't think as well under pressure, which is its own kind of distractor. And those little questions that give rise to self-doubt are some of the most powerful distractors, because they interfere with the process they reference.
Why do dogs ape if apes don't ape?
Range, Viranyi and Huber (2007) found that dogs exhibit imititative learning:
The transmission of cultural knowledge requires learners to identify what relevant information to retain and selectively imitate when observing others' skills. Young human infants — without relying on language or theory of mind — already show evidence of this ability. If, for example, in a communicative context, a model demonstrates a head action instead of a more efficient hand action, infants imitate the head action only if the demonstrator had no good reason to do so, suggesting that their imitation is a selective, interpretative process [1]. Early sensitivity to ostensive-communicative cues and to the efficiency of goal-directed actions is thought to be a crucial prerequisite for such relevance-guided selective imitation [2]. Although this competence is thought to be human specific [2], here we show an analog capacity in the dog. In our experiment, subjects watched a demonstrator dog pulling a rod with the paw instead of the preferred mouth action. In the first group, using the âinefficientâ action was justified by the model's carrying of a ball in her mouth, whereas in the second group, no constraints could explain the demonstrator's choice. In the first trial after observation, dogs imitated the nonpreferred action only in the second group. Consequently, dogs, like children, demonstrated inferential selective imitation.
Last year I posted on "imitation" in infant macaques, and noted that the term has induced a lot of confusion:
Lately, the term has been limited to cases of learning where an individual is replicating the behaviors of another individual -- not only the end result, but also all the steps that lead to that end result. But the infant "imitation" quite clearly doesn't require the kind of conceptual learning that instances of "imitation" among older juveniles and adults seems to take.
The issue remains quite confusing, although there are clarifying statements on the issue to be found in the literature. A good discussion of the concept of "imitation" as applied to social learning in particular was provided by Byrne and Russon (1998), who interpreted learning of action sequences from the perspective of hierarchization:
To explain social learning without invoking the cognitively complex concept of imitation, many learning mechanisms have been proposed. Borrowing an idea used routinely in cognitive psychology, we argue that most of these alternatives can be subsumed under a single process, priming, in which input increases the activation of stored internal representations. Imitation itself has generally been seen as a "special faculty." This has diverted much research towards the all-or-none question of whether an animal can imitate, with disappointingly inconclusive results. In the great apes, however, voluntary, learned behaviour is organized hierarchically. This means that imitation can occur at various levels, of which we single out two clearly distinct ones: the "action level," a rather detailed and linear specification of sequential acts, and the "program level," a broader description of subroutine structure and the hierarchical layout of a behavioural "program." Program level imitation is a high-level, constructive mechanism, adapted for the efficient learning of complex skills and thus not evident in the simple manipulations used to test for imitation in the laboratory. As examples, we describe the food-preparation techniques of wild mountain gorillas and the imitative behaviour of orangutans undergoing "rehabilitation" to the wild. Representing and manipulating relations between objects seems to be one basic building block in their hierarchical programs. There is evidence that great apes suffer from a stricter capacity limit than humans in the hierarchical depth of planning. We re-interpret some chimpanzee behaviour previously described as "emulation" and suggest that all great apes may be able to imitate at the program level. Action level imitation is seldom observed in great ape skill learning, and may have a largely social role, even in humans.
I think it may be valuable to add yet another hierarchical level below the "action" level; perhaps a "fine motor" level of imitation. This would be the level that fine imitation of motions like a tennis swing occupy -- people learn these through intensive practice, including slow breaking-down of the motor sequence into separate steps that are put together into a single rapid motor performance. This kind of motor imitative learning may not be present in any other animals -- in fact, I doubt there is any evidence of this in prelinguistic hominids. Perhaps the process of analysis of action at this level requires language to negotiate the time scale of modeling and the process of segmentation.
Range et al. focus on a relatively simple version of imitative learning that involves some conceptual understanding of both the goals and the steps taken while performing an action:
This type of social learning from a conspecific model clearly exceeds purely motivational and perceptual forms of social influence, such as social facilitation and stimulus enhancement [22], as already demonstrated in dogs [23]. It also deviates from simple forms of behavioral matching, such as response facilitation, i.e., the priming of an action already in the repertoire of the observer [24], because, even though the pretest showed that all animals had paw use in their repertoire, observers of both experimental groups started out by using their mouth instead of the demonstrated paw action to manipulate the rod. The quick and radical shift in the mouth-free group to adopt the paw action, for which there is no tendency in the control group, indicates an imitative form of social learning according to Thorpe [25], e.g., "as a significant elevation in the frequency of an observed action over the normal probability of its occurrence" [26] (reviewed in 27, 28, 29, 30 and 31, but see also 32 and 33).
The experiment involved an apparatus that required the dogs to pull down on a rod to obtain a food reward. Naïve dogs tended to use their mouths on the apparatus. The experimenters set up some dogs so that they could see a trained dog pull down the rod with her paw instead of her mouth. And, this is important, the dogs were primed with communicative cues from the model dog and the humans. Then, these groups were allowed to try the apparatus; upon which a high fraction of the experimental groups started using their paws to pull down the rod.
So the dogs are imitating in at least a chimpanzee-like or toddler-like way. And we bred them to do it! That may indicate that the basis for this ability is relatively shallow, in that it can be elicited with concerted selection, and without a long process of specialized evolution.
References:
Range F, Viranyi Z, Huber L. 2007. Selective imitation in domestic dogs. Curr Biol (in press) doi:10.1016/j.cub.2007.04.026
Byrne RW, Russon AE. 1998. Learning by imitation: a hierarchical approach. Behav Brain Sci 21:667-684.
Horner V, Whiten A. 2005. Causal knowledge and imitation/emulation switching in chimpanzees (Pan troglodytes) and children (Homo sapiens), Anim Cogn 8:164-181
Whiten A, Horner V, Litchfield CA, Marschall-Pescini S. 2004. How do apes ape? Learn Behav 32:36-52.
Voelkl B, Huber L. 2000. True imitation in marmosets. Anim Behav 60:195-202.
House, M.D., biosemiotician
JACK: "I don't want to hear semantics."
HOUSE: "You anti-semantic bastard."
Earlier this year we started watching House, which has reruns on the USA network so we can catch up on last season as well. It's a great pleasure to see Hugh Laurie on American TV. You may remember him as Bertie Wooster, or the stuffy Prince of Wales in Blackadder -- or, let's face it, as Stuart Little's dad. On House, he plays the Gregory House, whose job is to figure out what is ailing sick people whom nobody else can diagnose.
For his portrayal, Laurie won a Golden Globe tonight, so I thought I would finish my notes about House, who makes for some interesting observations about biological phenomena and sign theory.
House has three important qualities. First, an old injury has left him with partial use of a leg and chronic pain, for which he depends (more or less addictedly) on pain meds. Second, he is the most cynically acerbic misanthrope on television, only a minor part of which is attributable to his injury. And third -- like most fictional sleuths -- he has a mysterious talent for arriving at the true explanation for symptoms that nobody else can figure out.
But unlike most fictional detectives, House and his team average around seven wrong diagnoses per episode before they finally arrive at the right one. That adds to the drama, but it also adds a bit of transparency to what is really going on. House is reading signs.
All medical diagnosis is essentially semiotic: the physician examines the patient, looking for signs. Sometimes these are physical or physiological signs -- a swelling on the knee, vomiting, blood. Sometimes the signs can't be directly observed, but are communicated by the patient: nausea, chills, pain in the chest. The doctor has a script intended to discover these patient-reported signs: "Are you feeling light-headed? Any pain? How often do you have these spells?"
When a physician makes a diagnosis, she has found a set of these signs that point to an underlying disease or condition with some fidelity. Sometimes it helps to know how a disease progresses, but this is not strictly necessary. It almost never requires knowing why the disease exists. The evolutionary origins of many human diseases are mostly or entirely unknown, and physicians do quite well recognizing and treating them without any such knowledge. Together, these facts imply that the mechanism by which a disease causes a symptom is not necessarily of importance to the physician; the symptoms are quite sufficient in themselves as signs. Hence, Galenic medicine managed to diagnose many illnesses quite accurately while clinging to a humeral theory of physiology, lacking any notion of the germ theory of disease, genetics, or even circulation of the blood!
What is crucial is the mind of the physician. A sign is a triadic (three-way) relation: in the terminology of Peirce, the sign involves not only the signifier and signified (the colloquial "sign" and its object) but also the interpretant: the third thing to or within which the relation between signifier and signified is instantiated. In other words, there is no sign without a witness. With most illnesses, not just single events (fever) but constellations of many events (three days of fever, nausea, redness of the scalp) are the signifiers. It takes training to recognize the essential differences between such constellations. Each symptom has some probability of occurring or not occurring with any disease, which may depend on the patient's history, diet, or genes. Putting everything together is a complex problem of interpretation.
Take this scene from a recent House episode:
House barges in on Cuddy as she is seeing a clinic patient, who is a 15-year old dwarf named Abigail. The mother of the girl, Maddy, is equally diminutive. House demands his pills from Cuddy and offers to take the case in exchange. He rudely assumes that it is relatively simple because the girl has a popped lung. Maddy notes that both she and her daughter have Cartilage-Hair Hypoplasia. House grabs the case file, again asks for his pills and retreats to the office to find his team.
House sets about diagnosing the girl, but other plot elements get him bounced off the case. Still, he predicts the course of system failure that is to follow, and the girl's condition deteriorates as predicted. The team spends most of the episode arguing about whether the disease is some unrecognized cancer, or whether it is an unrecognized autoimmune disorder, and the girl responds temporarily to several different treatments, but ultimately the decline continues.
An argument with another little girl about whether her stuffed animal is a dog or a bear triggers a realization in House: just because the patient has been called a dwarf doesn't mean she necessarily is one. An X-ray reveals that the patient has entirely normal epiphyses on her bones; she doesn't have the Cartilage-Hair Hypoplasia, but everyone had assumed she inherited it from her mother. In this case, the lack of another disorder is a new sign, one pointing to the pituitary gland. A scan shows a granuloma, which after removal will cure the condition.
This sounds like a standard hour-long TV drama twist. And certainly, it is at least that -- these little jinks in the last ten minutes are the main payoff of most episodic stories. But in an hour-long format usually devoted to a single case, there is much more time for putting together complex puzzles than in the CSI-like crime shows, where detectives usually are split into two (and sometimes more) cases that each have a hidden smoking-gun clue. The leader of the genre, CSI itself, derives much interest from cases that are intrinsically rare -- like the killer who evaded DNA tests because he was a chimera, and knew it! House has its share of vanishingly rare diseases, but more often he faces common disorders that present with unusual symptoms, or the effects of two or more common diseases acting in conjunction with each other in unusual ways. A good example is a recent case where an active Legionella infection masked the toxic effect of an underlying fungal infection. Curing the Legionella left the more serious condition free to worsen, undiagnosed. This unexpected result created a new opportunity for interpretation, with a slightly different constellation of symptoms.
In this way, the show reflects medical practice as studied by biosemioticians. The idea of biosemiotics is that the events that organisms undergo constitute sign relations. Natural signs are involved in animal communication through pheromones or vocal and visual signals, observational learning and mate recognition. Medical practice has become a productive area for biosemiotic research, because it is a vast realm of knowledge based on the recognition of physiological and psychological events.
For example, Thomas Ots (1992) studied the diagnostic practices of doctors in China and in Germany, finding two interesting things. First, Chinese doctors on average noted a greater number of symptoms for each patient -- 5.4 symptoms for Chinese patients and between 1.3 and 3.9 for German patients. Second, German doctors were much more likely to note pain as a symptom, and typically the first symptom registered -- 49 to 68 percent for German patients, only 24 percent for Chinese patients (Ots 1991:294). Additionally, the Chinese doctors noted not only more symptoms per patient, but a broader total spectrum of different observations.
Upon seeing these data, one might suggest that the Chinese doctors are simply noting a large number of irrelevant symptoms. In this view, the German doctors might be more likely to focus on the most diagnostically relevant symptoms, ignoring observations that might be ambiguous or lead to multiple possible diagnoses. Or perhaps the Chinese doctors simply spend more time collecting symptoms than the German doctors.
But Ots favored the interpretation that the two cultures differ in their perception of diagnostic value of different subjectively reported symptoms. This passage is illuminating:
Every medical system shapes and trains its patients' experience, perception, and labeling of bodily and emotional symptoms in different ways (Kleinman 1986:60). The Chinese are trained to pay great attention to bodily changes; their perception is aided by linguistic terms commonly shared among physicians and laymen. In the West, 'headache' and 'migraine' are terms commonly shared among laymen and physicians; but if a patient reports a non-painful sensation in her head -- e.g., pressure or a sensation of distention -- her physician feels uncomfortable because he feels unable to translate these sensations into objectifying medical language. He will ask her to proceed in the description of her symptoms, or he will ask: 'Is it pain you are talking about?'
I worked as a physician in a traditional medical setting in the People's Republic of China. In my experience, at the level of symptomatology, there is little difference between laymen's colloquially used terms and the terminology of Chinese medicine. Little distinction is made between subjective and objective symptoms. One of the leading textbooks on differential diagnosis in Chinese medicine (Zhao 1984) lists almost 500 symptoms. The traditional terminology offers patients a wide variety of terms to help them express their perceptions. For instance, there are terms for heaviness of the head [touzhong] and the feeling of distention of the head [touzhang] that are missing in Western medical terminology (Ots 1992:292-293).
I haven't heard House talk about touzhang yet, but much of his technique consists of progressively adding more symptoms, both subjective and objective, to his team's deliberations. There is seldom a single key symptom -- unless it was one that happened to be missed in a false negative diagnostic test. There are often seemingly-minor pieces of a patient's history that lead to the right answer. Sometimes patients' subjective symptoms are to be trusted (listen to the patient), sometimes they are not to be trusted ("Patients lie").
The subtext is that signs of disease are mixed. Modern epidemiology emerged upon the foundation of Koch's postulates, which proscribed rules for supporting pathogen-disease associations. The postulates themselves have many exceptions, which have played out into the epidemiology of many human diseases. But in the age of genomics, we face the prospect that the classic epidemiological diseases are the simplest cases, and that the new challenges all present some kind of genomic, evolutionary, or combinatorial complexity. Diseases that act differently on different genetic backgrounds, pathogens that evolve within the body into more infectious forms, and different pathogens that interact with each other in complex ways.
These make House the perfect semiotician for the genomic age. His task is to find relations among signs, which have relevant meaning only in combination. The diagnostic paths taken are diverse because there is no single method that can find the meaning of different combinations. The process is led by the signs. It is a process of interpretation rather than of generalization -- hermeneutic rather than nomothetic.
References:
Ots T. 1992. The neglect of subjective medical data and the cultural construction of pain disease - a cross-cultural study. Pp. 283-300 in Biosemiotics: The Semiotic Web 1991, Sebeok TA, Umiker-Sebeok J, eds. Mouton de Gruyter, New York.
Information measures
Pp. 66-67 in Entropy for Biologists by Harold J. Morowitz, Academic Press, New York, 1970 (emphasis added):
The logic of our approach may be difficult to follow since information is not a physical quantity in the sense that mass, charge, or pressure are physical quantities. Information deals with the usefulness of a set of symbols to an observer. Since information does not measure anything physical, we are free to choose any information measure we please. The definition is therefore at first arbitrary and the choice is based on a common sense estimate of the usefulness of a set of symbols. The original definition arixing from the needs of the communications industry was, to use P. W. Bridgman's words, "of such unblushing economic tinge." What in the end turns out to be surprising is that the definition which was introduced is found to relate to the entropy concept in interesting and very fundamental ways.
Randomness
From a passage on the statistical behavior of aggregates and probability theory, p. 64-65 in Entropy for Biologists by Harold J. Morowitz, Academic Press, New York, 1970:
The notion of randomness is a very important one in physics, yet difficult to describe. (Randomness has become so significant that one of the outstanding scientific publications of recent years was a book of one million random digits.) Often a process is so complicated or we are so ignorant of the boundary conditions, or of the laws governing the process, that we are unable to predict the result of the process in any but a statistical fashion. For instance, suppose we have a collection of radioactive phosphorus atoms, P32, and take an individual atom and question how long it will take to emit an electron. Here we do not know the boundary conditions, i.e., the detailed state of the nucleus, nor do we know the exact laws coverning radioactive decay. The time can take on any value. We may obtain an aggregate of such values as is done in experiments on radioactive half-lives and deduce certain features of the collection, but we may only make probability statements about the individual atom. Randomness is in a certain sense a consequence of the ignorance of the observer, yet randomness itself displays certain properties which have been turned into powerful tools in the study of the behavior of systems of atoms.
John Hawks Department of Anthropology
University of Wisconsin—Madison
Copyright © 2007 John Hawks