Medical Perception and the Blind Spot
The theory of observation and the blind spot
We all have the natural feeling to perceive an outer objective world. But, as we know, nothing can be more wrong than that. The fact that things are not the way we believe them to be has been a major topic in different sciences. Especially in physics there exists a clear concept in how the process of observing influences the outcome. For medicine a comparable theory of perception has never been formulated. There still prevails a kind of naive naturalism maintaining that health, disease and therapeutic interventions can be judged objectively. In this article I will review some facts contradicting this position. Two points, not necessarily always addressed, will be central. First, that perception is theory driven from the very beginning, and second, that there is always an unobserved field, an unrealized blind spot.
The fact that even the basic issues of perception depend on theories shall be demonstrated with three, somehow deliberate examples:
The necessity to organise incoming data according to theories in order to achieve a stable perception has been proved by Gestalt psychology decades ago. Experiments and experience have shown that social cognition works quite the same. However, we rarely experience that our perception is a theory and does not represent an objective world. This might happen when we are fooled by optical illusions or by the tricks of a magician. In social relations the incongruence between our theories and observations is sometimes felt in disappointing situations when persons turn out to be quite different than we experienced them to be. More often this phenomenon is seen in intercultural relations where others do not behave at all ‘how they should’.
Comparable situations in science occur when an observation cannot be explained by the traditional theories. Such irregularities are an indication that the used scientific approach (the paradigm) is not appropriate for describing the observed process (Kuhn 1970). The mostly used strategy to tackle such irregularities is to ignore them. This is supported by their labelling with so-called explanatory principles. Explanatory principles are words or expressions which seem to explain a whole range of phenomena but cannot be explained themselves (Bateson 1972: 38-58). That is, such words do not explain anything. They just remove the labelled phenomena from the frame of observation. In medicine, labelling with words like ‘psychological’ or ‘placebo effect’ is quite common. Unexpected developments become thus somehow explained, although nothing is gained.
Actually, a large unperceived area is produced following the same principles as the blind spot in neurophysiology. When you close your left eye and concentrate on the cross at a distance of about 20-30 cm the mouse vanishes. Only lines are left.
The explanation of the blind spot by the lack of receptors in the area of the visual nerve does explain why we do not see the mouse. It cannot, however, explain why we always see a whole picture. There are no gaps in our visual field. Von Foerster said: We do not see that we do not see (Foerster&Bröcker 2002).
This necessity to create an integral perception is particularly prominent in persons with an enlarged blind spot through stroke or tumours. For example, such a patient saw only half of the food on her plate and could, consequently, only eat this half, complaining that she was served too little. When the plate was turned she saw the food again, and again she could eat half of it (Sacks 1998: 77-79)
The same principles of perception prevail in science where a given epistemology creates a more or less large blind spot. But most scientists have the feeling of a complete system.
The theoretical and the phenomenological approach
With two accounts about people with ‘psychological’ problems these principles shall be translated into medical practice. The first text is by Alice Miller, a known psychoanalyst.
“A patient from an African family grew up alone with his mother after his father had died while he was still a very small boy. His mother insists on certain conventions and does not allow the child to be aware of his narcissistic and libidinal needs in any way, let alone express them. On the other hand, she regularly massages his penis until puberty, ostensibly on medical advice. As an adult her son leaves his mother and her world and marries an attractive European with quite a different background. Is it due to chance or to his unerring instinct that this woman not only torments and humiliates him but also undermines his confidence to an extreme degree, and that he is quite unable to stand up to her or leave her? This sadomasochistic marriage, like the other example, represents an attempt to break away from the parents' social system with the help of another one. The patient was certainly able to free himself from the mother of his adolescence, but he remained emotionally tied to the Oedipal and pre-Oedipal mother whose role was taken over by his wife as long as he was not able to experience the feelings from that period. In his analysis he encountered his original ambivalence. It was terribly painful for him to realize the extent to which he had needed his mother as a child and at the same time had felt abused in his helplessness; how much he had loved her, hated her, and been entirely at her mercy. The patient experienced these feelings after four years of analysis, with the result that he no longer needed his wife's perversions and could separate from her. At the same time he was able to see her far more realistically, including her positive sides” (Miller 1990: 61).
The other example is an account by Hahnemann. He treated a psychotic patient in 1792 (published 1796), at a time when mentally ill people were still held in chains, tortured and shown to the public. It was two years before Pinel in the Salpetière released the psychiatric patients from their chains, marking the beginning of a different psychiatric care which took another hundred years to be more generally accepted (Kraeplin 1962).
We will only give selections from the most striking parts relating to mental science, especially such as give the reader an idea of the gifted and comprehensive mind now distorted by the violence of the disease, but which, disordered as it was, yet aroused admiration.
Hahnemann devoted the first weeks to observation only, without giving any medical treatment to his patient. The latter spent day and night having a series of attacks; at one minute he spoke as a judge and delivered sentence; at another, he would recite as Agamemnon, or as Hector in the actual words of the Iliad, sung in the middle of a stanza of Pergolese's Stabat Mater; or he quoted passages from the Old Testament in the original Hebrew, or sought for an old Greek melody to a song of Anacreon or the Anthology; and again changed over to passages from Milton's " Paradise Lost " or Dante's " Inferno"; and from these again he would turn to algebraic formulae. Nothing was ever quite completed, but the new idea displaced the former with violent haste.
"The marvellous part," says Dr. Hahnemann, " was the correctness of expression of all that his memory recalled from writings in many languages, especially of all that he had acquired in his youth." This mixture bears testimony to his extraordinary and manifold knowledge, but perhaps also to his eager desire to be brought into prominence by it, as he did when he boasted of his intimate acquaintance with distinguished personages ; he was not free from this characteristic in his normal state. He smashed everything that came to hand at that period, even his piano, and this he put together again in a peculiar manner in order, as he said, to find a complementary note, the Proslambanomenon. This man, who ordinarily knew nothing of bodily ailments, once wrote out for himself a prescription to be immediately dispensed, the rare ingredients of which, according to Hahnemann's deposition, were so well chosen and arranged, and so correctly calculated for the treatment of a maniac of his type, that it could easily have been accepted as the work of a learned physician; had it not been that the absurd signature and directions for administering it were proof of a disordered mind. By what means did the spirit in the midst of the fog of a storm-tossed imagination, without chart or rudder, find its way to so excellent a remedy for insanity, and one unknown to many a doctor, seeing that he had no books in his possession? How did he manage to prescribe it for himself in the most appropriate form and dose? Almost as astonishing was the fact that during the worst period of his mental disorder, on being questioned, he would not only know the date (this perhaps was comprehensible, although he had no calendar) but also the correct hour by day or night with great exactitude. As he began to improve, this power of divination became more uncertain and unreliable until with the complete return of his reason he knew neither more nor less about it than an ordinary person. When he was completely cured, I pressed him once in a friendly way to solve this riddle for me, or at least to describe the sensation that had prompted him. "My whole body shudders," he replied, " and something cold runs over me when I try to think of it; I pray you not to remind me of this thing . . ."
At the beginning of his recovery he had a ravenous appetite (ten pounds of bread a day besides other food did not satisfy him); at the same time he showed a tendency to deceive and offend everybody, and yet when well again he ate moderately and behaved courteously to everyone these are symptoms previously observed in similar patients. (Haehl 2, 1991: 34)
Miller’s account provides only those observations in line with her theories. Every statement makes sense to those acquainted with psychoanalysis. But we learn more about Miller’s theories than about the patient. Hahnemann’s account, in contrast, is full of unexplained and unexplainable observations. One might even ask why he describes all this.
This illustrates a central dichotomy in observation: Descriptions and observations which refer to causes are more theory orientated than when they refer to effects and a description is less phenomenological the more theoretical it is (Hanson 1972: 60-62). That is, a causal description is necessarily poorer and less complete than a phenomenological description. This creates problems as already stated by Bernard, one of the main founders of scientific medicine. He said „An experimenter, who clings to his preconceived idea and notes the results of his experiment only from this point of view, fails inevitably into error, because he fails to note what he has not foreseen and so makes a partial observation“ (Bernard: 23). And he concluded: “Men who have excessive faith in their theories or ideas are not only ill prepared for making discoveries; they also make poor observations” (Bernard: 38).
This dichotomy is not a consequence of today’s scientific thinking but inherent in all medical practice. Already Celsus’ distinction between a theoretical and empirical medicine, written in the 1st century, describe this inherent tension which in modern terms is called the opposite of generalization and individualization (Celsus: 7-27).
Hahnemann was a representative of the then evolving romantic medicine which believed in the individual value of man, therefore he was interested in the individual person with all its subtleties. As individual values were no issue for medical thinking before and later, detailed and individual descriptions of psychotic processes have never been of special concern in medical literature. It was more a subject for artists. In today’s medicine, where diagnosis and therapy are mainly based on statistics, individuality is rather regarded as a nuisance.
This lack of interest in the individual impressed me already at university. When we were first presented a psychotic patient hearing voices, we wanted to know more about these voices, what they said, what they meant in the context of the patient, and so on. But all discussion was interrupted. It was sufficient for the diagnosis and the therapy that he heard voices. Everything else was mysticism. This is how poor observers are educated.
Maybe the best account of a psychotic state is the autobiography of John Perceval who described the development, the crisis and the recovery of his psychosis in 1830-1832 giving precious insights into the disease (Bateson 1974). For example, he stressed that the usual behaviour of his environment maintained and increased his symptoms and that finally a good and supporting treatment helped him to recover. (1)
Perception creates reality
The first consequence of a poor observation is that too many things are ignored such that a diagnosis or an opinion when once established is not changed even if wrong. Known is the experiment by Rosenhan and co-workers. They asked to be voluntarily admitted into psychiatric claiming to hear voices and asking for help. Once hospitalised they behaved totally normally, or as normally as they could. The duration of their ‘treatment’ ranged between 7 and 52 days. No one was unmasked as a fake patient by the staff (although other patients realized). What ever they did was seen as confirming the diagnosis (Rosenhan). This was, unfortunately, not a singular case. A German girl was diagnosed to be hebephrenic by a psychologist at the age of 14. She was put into psychiatry where she showed resistance. She was treated with different drugs and entered a cycle of resistance and ever more drugs. Sometimes she was so drugged that she could hardly move or swallow, which reaffirmed the diagnosis. After more than 30 years the European Court of Justice released her as it found that the first diagnosis was not properly made and the further diagnoses were just a continuation of the first one. Actually the girl/women never had been ill, but showed normal reactions to drugs and a normal resistance to unfair imprisonment (Ehlers 2005). That is, in this case a given diagnosis connected with certain theories and a style of observation produced the symptoms which confirmed the diagnosis. This recursive process is the core of an attitude which has been called asylum mentality in psychiatry (Foucault 1965).
Such recursive processes are quite common. It is, for example, well known that children of single parents have more problems than children with two parents. They have an increased risk of psychiatric diseases, suicide or suicide attempt, injury and addiction (Weitoft 2003). It is, indeed, a severe problem. All single parents know this burden and many feel guilty. They live in an atmosphere of uncertainty and shame. This situation is the ideal breeding ground for abnormal behaviour, making it nearly inevitable for a child to behave strangely. And even if they don’t, a slight ‘abnormality’ that might be thought of as a normal problem of adolescence in other children is interpreted as a consequence of the single parent status. Then all kinds of helpers (doctors, psychologists, social workers, teachers, kindergarten teachers and neighbours) will intervene. Their help normally worsens the situation of which the unsocial behaviour is the consequence. Now we have the following phenomenon: If we assume that the first study about the difficulties of children of single parents would have been false (which is nothing special in medicine and social sciences), the spreading of this ‘knowledge’ through radio, television and hundreds of newspapers, through paid and non paid helpers could have made it a self-fulfilling prophecy. As a consequence a second or third study would then, correctly, find that children of single parents have more problems. That is, psychology might create the problems it finds.
Such a creation of diseases is not limited to psychological disturbances. For example, it is normal to wake up several times a night. This becomes a problem only when it is seen as problem. Then, the idea of having a problem prevents sleep (Bachmann&Steinhilber 2004). A real disease is created, when the physician gets involved and a person attains the official status of a patient. He might take drugs which cannot be discontinued easily, as the rebound effect provokes sleeplessness.
The list of self-fulfilling prophecies is long and the patterns are often subtle. Chronic rhinitis can be induced by nasal sprays. Hypertension might be created through the fear of having hypertension and the sight of the blood-pressure meter. Or: the more women are tested for breast cancer the higher is the incidence of breast cancer in women. And although ever more cancers are successfully treated there is no reduction of mortality in women (Gøtzsche & Nielsen 2006). This can be explained by the fact that many of the cancers would never have created any problems in the lifetime of the patient and that the treatment of breast cancer has side effects. Furthermore, there are many false-positive results. That is, women are diagnosed as having cancer who actually have not. Then the further diagnostical procedures put them at risk for side effects. But, even more importantly, these women live for months or even years in an atmosphere of fear and anxiety, and stress is known to promote cancer growth (Yang et al 2006). But despite the lack of benefits of mammography testing for breast cancer, many physicians just perceive the opposite: women are helped by testing.
It is certain also that physicians in the 17th century saw mainly positive effects of bleeding, enema and the artificially administered abscesses or burns used to ‘draw off the disease’ according to the then prevailing paradigm. Hahnemann, as an excellent observer, noticed, however, that this practice did more harm than good. His rift with the medical community came when he accused the private physician of emperor Leopold II of killing his patient by too many bleedings. He wrote:
The bulletins (of Leopold’s physician) state : "On the morning of February 28th, his doctor, Lagusius, found a severe fever and a distended abdomen" he tried to fight the condition by venesection, and as this failed to give relief, he repeated the process three times more, without any better result. We ask, from a scientific point of view, according to what principles has anyone the right to order a second venesection when the first has failed to bring relief? As for a third, Heaven help us!; but to draw blood a fourth time when the three previous attempts failed to alleviate! To abstract the fluid of life four times in twenty-four hours from a man, who has lost flesh from mental overwork combined with a long continued diarrhoea, without procuring any relief for him! Science pales before this!" (Haehl 1, 1991: 35)
Bleeding has negative effects. This was Hahnemann’s observation challenging the paradigm of the time. So far, this is nothing special, as there were always physicians who understood quite early that certain practices are not for the benefit of patients. In the frame of a study of medical perception this episode becomes interesting when it is compared with a statement of Magendi, who was not only one of the most famous doctors of his time, but is considered today as the founder of modern physiology and pharmacology. Magendi, about 40 years after Hahnemann’s fiery accusation, made fun of his colleagues who bled in pneumonia on the side of the inflammation. Since Harvey (i.e. for 200 years) they should have known that both sides are connected, so bleeding is possible at both sides (Lichtenthaeler 1975: 447).
This example demonstrates that scientific knowledge does not enable one to perceive harmful developments and therapies. Venesection was finally abandoned in a quite modern way. Bernard proved statistically in comparative studies that there is no beneficial effect of bleeding in pneumonia (Bernard 1957: 195).
The blind spot of statistics
The statistical method became central in current medicine where it is called evidence based medicine. It has proved the effectiveness of many therapies and the ineffectiveness or harm of many others like bleeding, preventive mammography, hormone replacement therapy in menopausal women or cortisone after head injury.
But also evidence based medicine has a large blind spot: For hormone replacement therapy in menopausal women there have been hundreds of statistics showing that this therapy is effective and safe. A year before the New England Journal of Medicine published the WHI-study demonstrating that this therapy did more harm than good the same journal published a positive study of which the related editorial said: “Good news about oral contraceptives: The development of oral contraceptives stands as a major advance in women's health in the past century” (New England Journal of Medicine editorial 2002). This discrepancy points to a central problem of statistical medicine: Only large studies involving hundreds of persons with a duration of several years provide statistically reliable results. But such studies exist only for a few treatments. But even if reliable results exist there is no certainty that these results can be applied to a certain person. The question remains whether findings true for a vegetarian English woman doing sports are still true for an obese smoking Hungarian man. This blind spot has been formulated as follows: “Large numbers show a statistically exact result. But nobody knows for whom it is the case. Small numbers show a statistically unsuitable result, but we know whom it concerns. Difficult to say which kind of ignorance is more useless” (Beck-Bornholdt&Dubben 2003: 218, my translation).
This contradiction between generalisation and individualisation is a central problem of medicine. What is true for the individual might not be true for the population and vice versa.
Observation and action
Oliver Sacks, an American neurologist, became famous for his accounts of neurological cases which challenge the linear thinking of our current medical paradigm. His first account was his own case, where, after the immobilization of a fracture of his leg, he developed pseudoparesis without nerval lesion. It is impossible to define what he exactly had, as there is no neurophysiological tool to do so. Sacks described it as a somatic scotome, as a disturbance of the plan of the body. The immobilized leg was eliminated from the inner representation. It was an unbelievable situation for him and for all of the consulted doctors. However, Sacks’ later investigations showed that this phenomenon was quite common. It was known by patients as they suffer from it. But it was overseen by doctors as they had (and have) no theory to describe it (Sacks 1984).
In a later book The man who mistook his wife for a hat (Sacks 1998) Sacks gives a collection of cases which demonstrate that our current understanding of the function of the brain is deficient, or better: wrong. He describes how certain abilities arise in patients with brain disease or brain injury, abilities that are known only from patients with outstanding talents. He called these abilities excesses. Sacks shows that these cases can only be approached when all linear assumptions are left behind.
“’Deficit’...is neurology’s favorite word its only word, indeed, for any disturbance of function. Either the function (like a capitor(capacitor?) or fuse) is normal or it is defective or faulty: what other possibility is there for a mechanistic neurology, which is essentially a system of capacities and connections? What then of the opposite an excess or superabundance of function? Neurology has no word for this because it has no concept. A function, or a functional system, works or it does not: these are the only possibilities it allows. Thus a disease which is ‘ebulient’ or ‘productive’ in character challenges the basic mechanistic concepts of neurology, and this is doubtless one reason why such disorders common, important, and intriguing as they are have never received the attention they deserve” (Sacks 1998: 87).
An example of such ‘excesses’ are hypermnesia or hypergnosia or Klockenbrink’s exact feeling of time as described by Hahnemann. Such phenomena cannot be modelled by orthodox medicine. Therefore they are normally ignored.
The most incredible case of such an observation concerns syphilis and is, again, by Hahnemann. It would be unbelievable, if he were not such an excellent observer in all other cases. Current textbooks describe the development of syphilis as follows: At the place of contact, mostly the genitals, the germ Treponema pallidum produces an initial lesion, the so called chancre, accompanied by a swelling of the regional lymphe nodes. This represents the first line of defence. The chancre ‘heals’ within several weeks spontaneously. Still during its presence or even months later a general eruption occurs, the so-called secondary stage with a dissemination of the germ all over the body. Also this secondary rash vanishes spontaneously and the disease remains again silent for years. About a third of the patients will suffer from the late syphilis (syphilis III) characterized by tissue destruction of all kind of organs (skin, lungs, heart, aorta, brain etc.).
Now, Hahnemann maintains that during his more than 50 years of practice he never saw Syphilis stadium II or III if the initial lesion, the chancre, remains untouched. The chancre, if not treated, might persist even for years (Hahnemann 1835: 15).
As this observation is against all medical knowledge, the question arises whether it really might be possible that all medical textbooks are wrong. Will every physician or the patient himself treat the initial lesion? Yes, it is possible. Whoever saw a picture of the chancre will understand that every patient wants to get rid of the primary lesion. But as a consequence (s)he will intervene into the balance of the immune defence.
This example points to a more general problem: We have nearly no idea of how processes develop without intervention. Everything is treated with drugs, creams, surgery or whatsoever. Rarely a disease is left to its real natural course.
But although many treatments are superfluous, in the normal case the physician has to act. But in acting he changes the course of events. He will never encounter the same situation again. This makes medicine the most non-trivial of all sciences. A physicist might smash a nucleus again and again. A chemist might repeat his reactions as often as he wishes.
A physician lives in a totally recursive world without a stable frame of observation. Even when doing nothing ? the preferable therapy of Bleuler which he called in Latin udenotherapy (Bleuler 1962) ? this will induce a change in the patient according to the personality of the physician. Just as it is impossible not to communicate (Watzlawick et al: 51) it is impossible for a physician not to act. Also a physician in the hospital not seeing the patient communicates in not seeing him, which might have a tremendous impact.
The limits of knowledge
How could it be possible that such an effective medicine as ours should have such a large blind spot? The answer is simple: Current medicine is not nearly as successful as assumed. Today’s longevity is mainly due to the reduction of infectious diseases (Fintch/Crimmins 2004). This reduction has been a steady decline since the middle of the 18th century and was uninfluenced by the introduction of antibiotics and vaccinations as exemplified with the case of scarlet fever (Hiatt 1975: 42).
It is difficult or impossible to assess what caused this change. But one thing is for sure: modern medicine was not (overview in Illich 1999).. But as the decline was so impressive, especially in the sixties the WHO believed that all disease might be defeated by the end of the millennium. Notorious became the statement of the US Surgeon General in 1967: “The war against infectious disease has been won” (Morens et al 2004). But as we all know this belongs to the outstanding mistakes in scientific thinking, comparable to the resignation of the chief of the American patent office around 1880 with the explanation that all major inventions had been made.
But we are far from a ideal situation, although our perception often suggests this. An investigation of traumatized soldiers of the battles of Waterloo and Trafalgar revealed that “despite the non-existence of antisepsis, antibiotics, blood transfusions, life-support machines and other paraphernalia of modern intensive care, most of these soldiers recovered, often from life-threatening injuries. Yet with all our technical advances in medicine, mortality rates from conditions such as serious infection have not improved dramatically over the past fifty years” (Singer M 2004).
These examples demonstrate that our medical perception is far from being complete and that the current medical paradigm, as every paradigm before, reveals only certain traits, is only a partial map to a necessarily unknown territory. Understanding the conditional nature of medical observation, a lot new could be discovered.
Adams WJ, Graf EW, Ernst MO (2004): Experience can change the 'light-from-above' prior, Nature Neuroscience 7: 1057 - 1058
Bachmann K, Steinhilber B (2004): Die Geheimnisse der Nacht, GEO 8: 210-230
Bateson, Gregory (1972): Steps to an Ecology of Mind. Ballantine, New York
Bateson, Gregory (ed.) (1974): Perceval’s Narrative A Patient’s Account of His Psychosis 1830-1832. William Morrow, New York
Beck-Bornholdt HP, Dubben HH (2003): Der Schein der Weisen. Rowohlt, Reinbek bei Hamburg
Bernard C (1957): An Introduction to the Study of Experimental Medicine. Dover, New York
Bleuler E (1962): Das autistisch-undisziplinierte Denken in der Medizin und seine Überwindung, Springer, Berlin
Celsus (1935): De Medicina I, William Heinemann, London
Ehlers F (2005): Das böse Kind, Spiegel 37: 78-84
Finch CE, Crimmins EM (2004): Inflammatory Exposure and Historical Changes in Human Life-Spans, 305: 1736-1739
Foerster Hv, Bröcker M (2002): Teil der Welt. Carl-Auer-Systeme, Heidelberg
Foucault, Michel (1965): Madness and civilization: A history of insanity in the Age of Reason, Harper & Row, New York
Gøtzsche PC, Nielsen M (2006): Screening for breast cancer with mammography. Cochrane Database of Systematic Reviews 2006, Issue 4, DOI: 10.1002/14651858.CD001877.pub2 accessed 21.11,2006 available
Haehl R (1991): Samuel Hahnemann . His Life & Work. Jain, Kalkutta 1991, Vol 1 and 2
Hahnemann S (1835): Die chronschen Krankheiten, Arnoldsche Buchhandlung, Leipzig, reprint: Orgon, Berg am Starnberger See
Hanson NR (1972) : Patterns of Discovery. Cambridge University Press, London, New York
Hiatt HH (1975): Environmental factors in disease, in: Beeson PB, McDermott W (eds): Textbook of Medicine. Saunders, Philadelphia: 40-43
Howe CQ, Purves D (2005) : Perceiving Geometry : Geometrical Illusions Explained by Natural Scene Statistics, Springer, Berlin
Illich I (1999): Limits to medicine: Medical Nemisis the expropriation of health Boyars, London
Kraeplin E (1962): One hundred years of psychiatry, Philosophical Library, New York
Kuhn T (1970): The Structure of Scientific Revolution. University of Chicago, Chicago
Lichtenthaeler C (1975): Geschichte der Medizin. 2 vol. Deutscher Ärzteverlag, Köln
Miller A (1990): The drama of the gifted child, Basic Books, New York
Morens DM, Folkers GK, Fauci AS (2004): The challenge of emerging and re-emerging infectious diseases, Nature 430: 242 - 249
New England Journal of medicine editorial (2002): Good news about oral contraceptives, N Engl J Med 346:2078-2079
Rosehan DL (1973): On being sane in unsane places, Science 179: 250-258
Sacks, Oliver (1984): A leg to stand on, Gerald Duckworth & Co, London. Page citation of the German translation (2003): Der Tag, an dem mein Bein fortging, Rowohlt, Reinbek bei Hamburg
Sacks, Oliver (1998): The Man Who Mistook His Wife for a Hat. Touchstone, New York
Singer M (2004): Waterloo and medicine today, UCL, London’s Global University news December, available
Watzlawick, Paul; Beavin, Janet Helmick; Jackson, Don D. (1967): Pragmatics of Human Communication. Norton, New York
Weitoft GR, Hjern A, Haglund B, Rosen M (2003): Mortality severe morbidity and injury in children living with single parents in Sweden: a population based study. Lancet 361: 289-95
Yang EV, Sood AK, Chen M, Li Y, Eubank TD, Marsh CB, Jewell S, Flavahan NA, Morrison C, Yeh PE, Lemeshow S, Glaser R (2006): Norepinephrine Up-regulates the Expression of Vascular Endothelial Growth Factor, Matrix Metalloproteinase (MMP)-2, and MMP-9 in Nasopharyngeal Carcinoma Tumor Cells, Cancer Res. 66: 10357-10364
Georg Ivanovas (2008): Medical perception and the blind spot, in: Gormly, J., Klien, M. & Valk, S. (Eds.), Framemakers: Choreography as an Aesthetics of Change, Limerick: Daghdha Dance Company