Science & Technology

Antidotes and anecdotes: The dangers of an over-reliance on personal experience

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Everyone has had that one encounter with a friend, relative or acquaintance in which we are told they have cured themselves of some ailment or illness with a technique or remedy that would be considered very much outside the general ideas of what constitutes medical intervention. This can range from innocuous claims such as “placing an onion in my sock overnight cured my cold” to incredibly damaging and potentially life-threatening statements such as “I was cured of breast cancer with vitamin C treatment.” The whole reason the alternative medicine industry exists is that, as a species, we find anecdotal evidence extremely compelling.

The recount of anecdotes may well be important in the recollection of events and the reconstruction of narratives, few would argue that legal cases would in many cases stall without some reliance on testimony. The danger is over-extrapolating the relevance of personal experience. Consider a witness to a road traffic accident. Their eye-witness account may well be vital in establishing who is ultimately responsible for this incident, but quickly fails if the eye-witness attempts use this experience to make conclusions about the driving ability of a particular demographic or the safety of a particular brand of car of even the safety of a particular road. Doctors often rely heavily on their patients’ personal accounts of ailments to support diagnosis and methods of treatment. But it is when anecdote is used solely to support a claim which can be verified scientifically that we come unstuck, often with tragic consequences.

Recounted experiences also strongly influence our feelings towards our communities and those around us. Who hasn’t heard or seen someone complaining that their area or neighbourhood isn’t as safe as it once was? These opinions are rarely informed by crime statistics, but on tales heard from friends, recounted on social media or in the local press.

Moon madness

We all know that the term “lunacy” arises from a connection to the moon, but has the correlation ever relied on more than anecdote?

Anecdotal evidence is also used to justify ideas that are otherwise unsupported. The continuation of many pseudoscientific and supernatural beliefs can be attributed to our propensity to accept anecdote. Consider the often-quoted and demonstrably false theory that human behaviour is somehow affected by the moon’s cycles, with full-moons, being considered a harbinger of unusual and often criminal behaviour. This is a belief that is extremely popular amongst those working in the emergency services and in the psychiatric field, in particular. This myth, which originated in the dark ages, now propagates through what is known as the file-drawer effect.

Imagine a busy night in the ER department, two staff nurses remark to each other “It’s crazy in here tonight. Must be a full-moon” When one of our nurses pops outside for a smoke or to make a phone-call he notices it is indeed a full moon. This seemingly confirms their mutual belief. Our nurse quickly runs back in to inform his colleagues that he has indeed confirmed the connection between the full-moon and increase admissions in the ER. But, what happens if our nurse doesn’t see a full moon. This doesn’t confirm his belief, he is unlikely to run back in and suggest that this casts doubt on his theory, not because he is dishonest or in denial, but simply because it’s unremarkable.

Anecdotes in alternative medicine

Lorraine Day and her alternative treatment for breast cancer “barley green”

Alternative medicine websites frequently market products; not with the results of peer-reviewed, double blinded clinical studies, but with various testimonials from customers who have used these products. Many alternative medicine vendors actively seek testimonials from customers. The danger being, that said testimonials often neglect to mention the conventional treatments that may have been used alongside the alternative medicines. In his blog Science-Based Medicine, Dr David Gorski recounts a striking story that demonstrates that with regards to the allure of testimony and alternative medicine, level of education and even prior medical experience is not necessarily a factor. Gorski tells us of Dr Lorraine Day who was Associate Professor of Orthopaedic Surgery at UCSF and Chief of Orthopaedic Surgery at San Francisco General Hospital in the 1980’s. Day developed breast cancer in the early 90’s and began a treatment of alternative medicine and prayer. In an infomercial designed to sell the product “Barley green”, Day claimed that after surgery she was “sent home to die” and that her alternative therapy had cured her cancer. What Day failed to mention in the infomercial, was that she had undergone a second surgical intervention and subsequently refused to release the full pathology reports detailing this. Nor did Day ever establish any form of clinical trial for her treatment programme. Potential sufferers scared and desperate who come across Day’s account may well forgo conventional treatment on the word of Day, who after all is a doctor herself.

A key factor in the failure of relying on anecdote in selecting a treatment is the fact that many illnesses are self-limiting, they resolve themselves without any specific intervention.  A friend recommending the “onion in sock method” as a treatment for the common cold may well support this idea with the statement “I placed the onion in my sock, and five days later I was completely over it” or words to that effect. Of course, that statement completely neglects the fact that the ailment was likely to have cleared up within that time span anyway. Likewise, with chronic diseases that are unlikely to disappear, some days are likely to be worse than others, with days of particular pain or infirmity returning to less difficult times. This is known as regression to the mean, and is very often attributed to some intervention, when in fact it had little to no effect.

The mention of effects of medicine cannot be allowed to conclude without mention of the placebo effect. Conventional medical interventions are specifically tested against placebo to ensure they are more effective than this psychological effect. This is rarely true of alternative medicines and those recommended by experience alone. When these treatments are tested against placebo, it’s even rarer that they prove to separate from dummy treatments in efficacy.

We must also consider a significant bias in the reporting of unsuccessful medical intervention, patients who try an alternative medicine that they don’t believe is effective are far less likely to report this. More worryingly, if conventional medicine also fails for these individuals, they are unable to report failures of the alternative remedies they may have tried alongside them.


We accept testimonials in almost all other areas of our life, why not in research, science and medicine?

The psychic industry is one that prospers on little more that positive word of mouth and misremembered anecdote

People can often be quite shocked, even offended, when doctors, scientists and sceptics refuse to take their personal experience as evidence of some claim. This is probably because they aren’t aware of how subjective their recounting of personal experience can be. The recollection of an anecdote is subject to a whole host of cognitive biases. Experiences are tailored to support our preconceived notions and beliefs, our retelling of them accentuates positive correlations and diminishes negative data sometimes removing it from the telling altogether. Ever wonder why so many people report unexplainably accurate readings given by psychics or mediums when you own observations of the same have been underwhelming? Sitters who often desperately want to believe what they are being told by the psychic “remember the hits and forget the misses”. They may well remember with clarity the name of a dead relative being given to them whilst forgetting the names thrown out that failed to connect. The scientific method aims, often with tremendous success, to remove personal biases from experiments and data collection and analysis. It’s the reason that, beyond the construction of a hypothesis from an unsupported observation, that anecdote has no place in science.


A stark lesson from recent history and current events

The disgraced Andrew Wakefield promotes his celebration of anecdote over evidence “Vaxxed”

Reliance on anecdote may not have much consequence in the recommendation of a film or a restaurant, but when this effect isn’t controlled for in medicine, it can have tragic results. In 1998, Andrew Wakefield and twelve other authors published a paper in British medical journal Lancet which implied that there was a causal relationship between the administration of the measles, mumps and rubella vaccine (MMR) and the onset of “behavioural issues” and autism. The paper was severely flawed to say the least, focusing on only twelve children all suffering from autism. No tests were performed on non-autistic children and the authors relied heavily on the testimony of the children’s parents who insisted that the problems had only manifested after the administration of the MMR jab. Further studies showed no positive correlation between the MMR and autism, and Wakefield was left disgraced when it was discovered in a 2004 investigation by Brian Deer, that he had a vested financial interest in the suspension of the MMR vaccine. A 2010 review by a GMC panel found Wakefield guilty of 30 charges including dishonesty and the abuse of developmentally challenged children, The Lancet retracted the paper and Wakefield was struck off.

Jenny McCarthy and Jim Carrey, one time darlings of the anti-vax movement

Unfortunately, Wakefield did not go quietly into the night, instead moving to America where he became a hero and a figurehead of a burgeoning anti-vaccination movement. The justification for the anti-vaccination stance is based purely on anecdote and the false correlation/causation link between autism and thimerosal; an ingredient in many vaccinations. This reliance on anecdote is prevalent in anti-vaccination film “Vaxxed” released in 2016 and directed by non-other than Wakefield himself. The film juxtaposes the emotional tales of tearful parents set to a back-drop of sentimental music against the cold, clinical words of doctors and scientists. Is it any wonder many watching the film take the side of the parents, who no-one would deny do deserve some sympathy? What kind of heartless individual would deny their suffering we may ask. This narrative is powerfully enforced when celebrities speak out regarding the vaccination/autism, often linking their first-hand experiences with their own autistic children to their outrage.

The cost of this reliance on anecdotal evidence is striking. Failure to vaccinate lowers the herd immunity to viruses, this leaves the most vulnerable in society such as newborns and the elderly at risk from death by preventable illness. The World Health Organisation (WHO) estimate that 2-3 million lives are saved every year by vaccination, adding that if more children were to be vaccinated this figure could rise by a further 1.5 million. Of course, the anti-vax movement is only partially responsible for the failure to vaccinate and other factors do play a part, but it’s influence is growing and it’s especially worrying that one of the most powerful developed countries in the world now has a leader who has expressed anti-vaccination opinions clearly influenced by personal accounts in the past.

Donald Trump communicating his anti-vaccination stance via his favoured method of communication

So what can we do?

Clearly better education and science communication is vital in combating the propagation of pseudo-scientific ideas, but reliance on ideas supported by anecdote alone can be combated with one simple question: “How do you know that is true?” Phrased in a non-confrontational manner, this alone can often plant the seed that gets someone thinking about how they assess claims and beliefs they hold true.


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