Archive for the ‘Logical Fallacies’ Tag
Carl Sagan supposedly once said that randomness is clumpy. It is my new favorite thing to say because it is so simple and it so effortlessly explains so much about our experience with the natural world. Sagan’s ability to offer up life-changing nuggets of rational thought like this was unmatched and his efforts to bring science and reason to the public have been sorely missed since his passing in December of ’96. If you haven’t read any of Sagan’s works, I highly recommend The Demon-Haunted World: Science as a Candle in the Dark.
If you have a coin, and an hour to kill, record the results of a few hundred flips and you’ll see what Sagan meant about the nature of randomness. You will inevitably record clusters of heads or tails that seem improbable. Runs of heads or tails five, six, even seven straight times wouldn’t surprise me at all. But eventually, the outcomes will average out to about half of the flips being heads and half resulting in tails. The more trials that you perform, the closer the outcomes will approach exactly 50% for each possible result. I’m assuming you aren’t using a trick coin of course.
I don’t think that very many people would argue with the fact that on average a coin flip is random chance, although there are still people out there who think that the Earth is flat and that Miley Cyrus isn’t a robot. But because of a deeply rooted cognitive bias, we tend to forget that randomness is clumpy. We accept the established odds overall, but not in short runs of randomness whether it is a series of coin flips or, for a more “real world” example from my line of work, the incidence of bacterial meningitis in neonates with fever. We do this despite the many cold doses of reality experienced over a lifetime of allowing the past results of a random process to influence our expectations of future results of that random process. This is the essence of the Gambler’s fallacy, an error in logic that can lead to the belief, for instance, that after five heads in a row there is a higher than 50% chance that the next flip will land on tails. There isn’t.
The cognitive bias which results in this commonly employed logical fallacy is, as is often the case, the result of an inappropriately employed mental shortcut. These shortcuts, known as heuristics, can be very helpful but sacrifice accuracy for efficiency of thought. In the case of the Gambler’s fallacy, the representative heuristic is to blame. If someone is aware of the fact that a result has a known frequency of occurring, such as the flip of a coin or the spin of a roulette wheel, they often mistakenly make the assumption that short runs will be representative of long runs. This means that a run of ten or twenty should be equally split between heads and tails, or red and black in the case of roulette (1), in the same way that a run of a million would be. But, once again, randomness is clumpy and short runs often have surprisingly unbalanced results.
I recently had a somewhat heated exchange on the comment section of a Facebook friend’s status update. My friend, a mother of three boys, was expecting her fourth child and had not found out yet whether this baby was a boy or a girl. She expressed her desire for a girl and a relative of my friend commented that the new baby would almost certainly be female because the odds were so highly in favor of such an outcome. It is true that the odds of having 4 boys in a row is very low, about 6%, but this was a classic example of the Gambler’s fallacy. I responded and an argument ensued.
Now I am the first to admit that I am somewhat of a drive by skeptic when it comes to Facebook. I rarely allow an opportunity for chiming in when I disagree with a comment to pass by. And I further admit that I recognize that this is probably a character flaw of mine, and that I have made more than a few people rather angry or at the very least somewhat uncomfortable when their comment section is hijacked. My wife thinks I’m as ass, and as with most things, she is almost certainly correct in her assessment. I’m working on it, but I just couldn’t pass up such a beautiful hanging curveball.
So what were the odds of my friend’s child being a girl? There are two ways to approach this problem with one of them being right and one possibly seeming right because of the representative heuristic. Readers of this blog should know that what feels right on a gut level is often completely wrong. First though, some basics on the determination of sex in humans (2).
Human infants are generally born as either male or female and the determination of sex is based on genetics. Most mammals, humans included, select gender using an XY system that most of you are probably fairly familiar with even if you don’t remember the specifics. Modern humans, individuals with genetic syndromes aside, have a genome which consists of 23 paired chromosomes. The pair that determines an individual’s sex are, not suprisingly, called sex chromosomes. Females generally have two X chromosomes (XX) and males have both an X and a Y chromosome (XY). It is widely considered, although there is some controversy, that human zygotes are inherently on the path towards being female at conception and that, if present, a single gene located on the Y chromosome alters this course resulting in male offspring (3).
Most cells in the human body are identified as diploid, which means that they contain the above mentioned 23 pairs of chromosomes (4). Reproductive cells like sperm and ova, known as gametes, are haploid in that they only contain one set of the 23 human chromosomes. This make sense because they will combine to form a diploid zygote at conception. The female ovum always contains an X chromosome. It is the male sperm which ultimately will determine sex because an individual sperm can carry an X or a Y chromosome. Which sperm fertilizes the impatiently waiting ovum is a crapshoot and it works out to a roughly 50/50 split between male and female embryos (5). Studies looking at large numbers of families have shown conclusively that even in the case of families with long runs of male or female children, the chance that a subsequent child will be male or female remains pretty close to 50/50.
So in the case of my friend with 3 boys and a bun in the oven, the likelihood of having another boy was 50%, not 6.25%. And the chance of finally having a girl was 50%. But let’s further explore the notion so strongly argued by my friend’s relative, that the sex of previous children impacts the sex of future children. As I’ve already explained, there is a perfectly reasonable cognitive bias to blame for this fallacious logic, the misuse of the representative heuristic. But for argument’s sake let’s assume that he was right. What would the mechanism for this be? How would past results impact future results of a seemingly random process like sex determination? Somehow the male sperm would have to be cognizant of the sex of prior children and to intentionally select an X or a Y chromosome carrying champion to breach the defenses of the female genital tract and fertilize the ovum, perhaps in an effort to maintain the appearance of randomness over multiple pregnancies. These diabolical sperm must apparently act to prevent our awareness of a grand conspiracy which hinges on there being a roughly equal number of male and female offspring. Are they psychic and able to probe the inner recesses of the male mind? We may never know the answer but there is something I do know: don’t anthropomorphize sperm, they hate that!
(1) I realize that the odds of that little white ball landing in a red or black slot isn’t exactly 50/50. The 0 and 00 green slots give the house a little edge. So does the booze.
(2) As opposed to alligators, for instance, the sex of which are impacted by temperature variations rather than genetics.
(3) Usually. Sex determination is very complex. There are certainly instance where the genotype (XX or XY) doesn’t match with the phenotype (outward appearance) but these are quite rare and beyond the scope of this post.
(4) This isn’t entirely accurate. Most cells in the human body are bacterial.
(5) There is some nuance to this naturally. There is the possibility of a minor influence by environmental factors or factors inherent to sperm carrying X versus Y chromosomes which may lead to a slightly increased chance of male versus female offspring in some women, or a slightly higher rate of male births than female across populations, but these differences are not meaningful. And unless you are making use of gender selection via technology, such as with IVF, any environmental changes made by families to encourage the birth of a prefered sex will not alter the outcome.
How is a doctor like a psychic? The answer is surprisingly simple. Despite sounding like the introduction for a bad joke, along the lines of “What is the difference between a doctor and a chiropractor?”, the comparison of physicians to those individuals claiming to call upon supernatural powers to gain access to previously unknown information holds true……sort of.
Like psychics, doctors make use of a particular set of unique skills to extract personal information from their patients. This is often done in such a way that patients are unaware of just how much they have revealed about themselves. This always involves simple and direct questioning, such as when the doctor asks a patient about their symptoms or whether they have had any surgeries in the past. But many of the questions asked by physicians do not intuitively have any connection to a patient’s concerns, such as when I recently asked the parent of a child with bloody diarrhea if they owned any turtles. Or when I asked the parent of a jaundiced infant if gallstones run in their family. A good doctor often must read between the lines and connect seemingly disparate lines of evidence to arrive at a conclusion which may not be obvious to the patient or family. And though the doctor is able to figure things out that they didn’t directly ask about, and had no foreknowledge of, no psychic powers are necessary.
The psychic, when performing a reading for a client, also probes or fishes for information. Sometimes they ask obvious questions, such as if the client has been having problems at work. Sometimes they make statements, such as when a psychic senses a problem in client’s chest or feels that someone from beyond the grave, whose name starts with an M, is present. Both physicians and psychics also make use of a visual examination to add to their impression about the patient or client, with hopefully only the doctor putting any physical examination skills into use. They both play the odds, making assumptions based on how likely something is to be true. A physician, for example, may look at a 5-day-old severely jaundiced infant at their newborn follow-up visit and, with a fair amount of confidence, focus the initial discussion on interventions for breastfeeding difficulty. Similarly, a psychic may look at a tearful young woman with no wedding ring on and bags under her eyes from a lack of sleep and make a high-yield assumption that she is having a relationship problem. But such indirect techniques are not necessary to be a highly successful psychic.
I’ll go ahead and reveal, not that it will come as a surprise to regular readers, that the evidence supporting the existence of psychic abilities is weak and doesn’t support acceptance. But it is accepted by large percentages of the American public despite a lack of both plausibility and of supporting research. It is easy to understand why, once reason has been set aside and a belief in psychic powers initiated, this belief is resistant to the assault of rational explanations. As with other similarly implausible notions, such as the proposed impact of the full moon on psychiatric symptoms or birth rates, confirmation bias serves as a powerful means of protection. Because of confirmation bias, we only seek out or remember information that confirms our beliefs. And we selectively interpret new information in such a way that our beliefs are not negatively impacted, thus avoiding the dreaded entity known as cognitive dissonance. When confronted, believers will generally offer up anecdotes and, in some instances, poorly designed pseudo-research but these primarily serve as means to prevent loss of belief. The big question is why do we believe in the first place?
It would be easy for me to chalk belief in psychic powers up to mental illness, or to gullibility. I could assume that all psychics are frauds and that they use trickery to convince us (1). I’m sure that many believers are nuts, and that many psychics are intentionally manipulating people for potential fame and fortune, but I’d wager these are in the minority. Most folks, psychic are psychic friend, are simply deluded, having fallen victim to what essentially are glitches in the otherwise pretty effective functionality of the human brain.
The human brain, magnificent though it may be, is perfectly suited for belief in the supernatural. Among the many traits that make humans successful as a species is our ability, if not our uncontrollable drive, to connect the dots. Our ability and urge to put two and two together, or however else you want to describe this uniquely human(2) capability, is a direct result of the evolutionary path we have stumbled onto. And it has always been at the heart of humanity wide improvement projects. But having a plump neocortex isn’t all vaccines and moon landings, unfortunately. With great brainpower comes an equally great ability to fool ourselves, and it has led to a vast array of irrational convictions and superstitious beliefs.
The reason for this is that, as good as we are finding meaning where it exists, we are equally adept at finding meaning where it doesn’t. We force patterns in random stimuli. We strive to piece together unrelated data points. Only humans, for example, can look at the pattern in a pine door and see the face of Jesus or hear discernible and meaningful words amongst the gibberish of a Beatles’ song played in reverse. And, because we just can’t help it, we absolutely love to make everything about us. The entire universe was created with us in mind, after all. At least it was according to the majority of humans alive today. But we are even better at this when it comes to making sense out of the world on a personal level. This is the very essence of superstition, isn’t it? The absurd belief that not only my life can be negatively or positively effected by meaningless actions such as walking under a ladder or carrying around a lucky rabbit’s foot, but the lives of others as well. The egotism involved in believing that forgetting to wear a pair of lucky socks might result in a football team losing a game is staggering. It is the assignment of personal significance to meaningless information that sets us up to fall for the primary means of being fooled, or fooling ourselves, into believing that some people, including ourselves, have psychic abilities. This fundamental method of deception is known as cold reading.
Cold reading is a method of manipulation that can be purposefully put into use by a trained charlatan to give the impression that they possess abilities beyond the natural world. It involves a variety of techniques that lead to the offering up of information, not by the psychic but by the person who has sought out the psychic(3) for guidance, or that take advantage of the human drive to find personal meaning in vague or random data. The general approach of the psychic is to throw out vague statements or questions and allow the client to either give visual cues that they have found meaning in something, perhaps with a slight smile or a change in body positioning, or to give verbal feedback which helps guide the reading down a certain path.
The following is an example of how a typical cold reading session might go:
Psychic Jim (PJ): I’m sensing a disturbance in your chest. Have you had problems with your heart, or your lungs, or anything in the chest?
Subject Sally (SS): Well, I cracked a rib once during a fight.
PJ: The spirits are telling me there has been conflict in your past, but no resolution. You should find this person and seek to make peace in order to find true happiness.
SS: It was during a kickboxing class and my partner accidentally kicked me in the side too hard. There weren’t any hard feelings.
PJ: Great! The spirits were unclear whether this conflict was in the past or if it was a current issue in your life. They are telling me that you have an easy-going nature. You are capable of forgiveness when others might become bound up in negativity. That shows great strength as a person!
Or like this:
Psychic Jim (PJ): There is someone here with us today Sally. The mist is heavy around them but I’m sensing a male figure who passed on recently.
Subject Sally (SS): One of the guys at the office died last week. A heart attack. We weren’t close. He was a hard worker though, and a nice guy. His name was Tim.
PJ: I’m sensing regret. Tim is telling me that he didn’t feel close to you and he wished he would have made an effort to get to know you. He’s saying that you were always such a positive presence at work. He says that you deserve a promotion!
SS: It’s my company. How could I be promoted?
PJ: The mist is heavy around Tim, I’m barely sensing him. He says that you were wonderful to work for.
Do you think that Psychic Jim demonstrated mysterious supernatural abilities? Subject Sally most likely does. Psychic Jim knows he doesn’t have to be right every time, or even very often. Or at all. He just had to make vague statements or questions and she filled in the details. He also skillfully was able to change directions when a path hit a dead-end, as it did when Sally revealed that Tim was an employee of hers and not a co-worker. Sally will very likely misremember that the information she gave, the cracked rib and the deceased man at work, was provided by the psychic. She will remember those pseudohits and forget the blatant misses. People want to believe, they want there to be meaning in the psychics statements, so they will force it and their brain will warp the memory. The positive nature of the psychics claims, that Tim was telling him how wonderful she is, only increases the likelihood of this happening. Psychics know that telling clients what they want to hear is the surest way to insure repeat business (4). This is why their readings consist of vague yet positive statements, along the lines of newspaper astrology sections, that almost anyone would feel fit them well. After all, don’t we all wish to be strong, capable of forgiveness and a positive presence at work!
Cold reading isn’t just a tool of charlatans, however. These techniques come into play unintentionally all the time. Some so-called psychics hone the skill over time with study and practice but many people are also naturally good at them. They are the people who consider themselves intuitive and really good at reading people. Rarely do these people believe that they are using psychic powers though but they also rarely understand that their ability isn’t all that special. Anyone can learn to convincingly cold read. Anyone can be a psychic. So it is easy to see how some professional mediums may actually believe that they have a special gift unexplainable by science, and that they are truly helping people. I disagree. Regardless of the intention, deception is very rarely justified.
So is your doctor a psychic? He or she is no more or no less psychic than that Tarot card reader in the local strip mall or even famous psychics like Sylvia Brown. As a doctor, I can promise you that if I were truly psychic it would make my job and my life much easier.
For a more humorous (in my opinion) take on the subject of cold reading, check out this satirical news story.
(1). They do use trickery in many instances of course. This post is about the practice of cold reading but there also exists what is known as hot reading. If you visit a psychic, or see one on television, who makes very specific claims be skeptical. There are innumerable cases of psychics and faith healers being busted using a variety of techniques to obtain information from a client or audience member without their knowledge. Infamous faith healer Peter Popov’s wife would mingle with a crowd before a show and then relay information she picked up to him via a hidden earpiece microphone. An episode of Penn and Teller’s Bullshit showed how a famous psychic invited friends of her publicist to a showing which was to be filmed for the program, and visited with the group prior to the reading. The episode showed how she clearly regurgitated information she had acquired during the informal pre-show chat as if she had obtained it using her psychic intuition. Also, use of the internet has made life much easier for so-called psychics looking for info on future clients.
(2). I know, I know. Simmer down all you animal lovers. I fully realize that there are myriad examples of problem solving in other species, even perhaps a limited grasp of the concept of time. I argue, however, that it is uniquely human to have a true understanding of cause and effect and an ability to make sense out of our environment to the degree that we do, for better or for worse. Although sometimes I think my cat Molly might be smarter than she looks. My dog Sock is just plain dumb though.
(3). I don’t mean to just pick on psychics here. Cold reading is a technique that is put into use by astrologers, faith healers, salesman, psychologists, and yes even well-meaning physicians.
(4). A psychic who likes to tell clients that their dead uncle thinks they were a douchebag will have short sessions.
In a prior post, I described one of the most vital supporting pillars of skepticism: the requirement for increasingly powerful evidence in support of claims that push the limits of plausibility and call into question fundamental aspects of our scientific knowledge. In this post, I’m going to reveal an inherent flaw in our ability to accurately interpret causal relationships in the natural world. This flaw, known as confirmation bias, serves as the driving force behind almost all unfounded belief systems and the primary reason why anecdotes and testimonials are unreliable.
Examples of confirmation bias are all around us. Nobody is completely immune to its sirens’ call, and partial immunity can only occur with awareness of the concept and a constant struggle to avoid its influence. The feeling one experiences when realizing that they are wrong, especially regarding something that they are emotionally invested in, is unpleasant to say the least. Our brains, and thus our minds, have evolved to avoid this feeling even if we must sacrifice an accurate assessment of reality. We do this via three different mechanisms, all of which revolve around our tendency towards biased selection of information that supports what we already believe to be true.
1. The selective collection only of information that confirms (biased collection)
2. The selective interpretation of information in such a way that confirms (biased interpretation)
3. The selective recollection of only information that confirms (biased recall)
The net effect of these mental mechanisms is the overemphasizing of only some of the available data or information regarding a claim. The best example that comes to mind, and one which melds this topic with the practice of medicine, is that of the commonly held belief in so-called lunar effects. This is the hypothesis that the full moon has effects on the human body. These include effects such as increased rates of mental illness and suicide, and spikes in birthrates. High percentages of medical and law enforcement professionals accept lunar effects as a true phenomenon despite the fact that they are highly implausible and have been thoroughly disproven by the collective data of over 100 studies. So why does this pervasive belief persist?
The answer is confirmation bias.
When a strange event occurs, or there is an odd cluster of events, during a full moon, such as the unlikely need for the delivery of a baby in a pediatric emergency department, many will assign a causal relationship (biased interpretation) because they already believe in lunar effects. Others may make the connection for the first time because of prior exposure to legendary effects of the moon as with werewolves or its association with witchcraft, or because, after the fact, they hear of the many unusual things that have happened during a full moon from coworkers (biased collection). They may link the full moon to the strange event simply because humans are uncomfortable with the random nature of the natural world and a full moon is sexy. As storytelling primates, we often force explanations where none exist, and we love a good tale. This is what humans have evolved to do, and we do it better than any other species. At times, we do it too well. When a strange event or cluster of events occurs when the moon isn’t full, no connection is made. We do not interpret this as evidence against the previously assigned causal relationship (more biased interpretation).
Over the years, as the number of shifts in the ED pile up and random weird events continue to occur both during and not during the presence of a full moon, we tend to only remember the former (selective recall). Also, because human memory is malleable and changes with time and multiple retellings as in a childhood game of Telephone, strange events that did not occur during a full moon can drift to fit our beliefs. The occurrence of an ED delivery two weeks before and five days after a full moon two years ago may morph into that night we had two babies born during a full moon. The memory, although as false as a blatant lie, is no less real to the individual recalling it.
All of this is reinforced by the popularity of the belief, and to a lesser degree by misconceptions regarding the actual effects of the moon on the earth. Think tidal forces. Yes, it is true that the human body is largely made of water but in reality I am exerting more of a tidal force, or gravitational pull, on my keyboard as I type this than the moon does from 239,000 miles away. In fact, there is more gravitational pull on the earth during a new moon than a full one because a new moon lines up with the sun. But because of the dramatic visual stimuli that a full moon provides, this post isn’t about new moon madness.
So what are we do to about confirmation bias? Is it really an unavoidable pitfall? Well, perhaps not entirely unavoidable but it is an obstacle that has felled even the most powerful of minds. The best defensive strategy against this hardwired mental defect is an understanding of the fallability of human perception. The best offensive measure is active exposure to information that does not fit within the cozy confines of our personal worldview. And giving scientific discovery more weight than personal anecdotes wouldn’t hurt either.
A few nights ago I happened to catch a thought-provoking line of dialogue while channel surfing. A fictional program involving alien visitors to Earth made use of the standard meet-cute to introduce a rugged, no-nonsense cab driver and a scientist specializing in astronomical anomalies. The astrophysicist, a believer in UFO visitation, called the cabbie a closed-minded skeptic. While I have no doubt that this was not the writer’s desired outcome, the character’s words were upsetting. They evoked a visceral feeling of intense frustration.
I’ve experienced such a sentiment many times before. All outspoken skeptics have. Usually it emerges, as depicted in the aforementioned film, via an offhand response to the questioning of a firmly held belief. Occasionally, it is expressed in more descriptive and well thought out language, such as in a more substantial discussion or a formal debate. Regardless, the intention and underlying psychological impetus is the same. And, it is always part of an ad hominem argument.
An ad hominem, as described by the New England Skeptical Society, “attempts to counter another’s claims or conclusions by attacking the person, rather than addressing the argument itself.” On their list of the top 20 logical fallacies, they use as a prime example of an ad hominem argument the very same one put into use by the movie’s UFO proponent: calling the skeptic closed-minded.
I have no doubt that some self-described skeptics are closed-minded. The term skeptic isn’t an earned degree. It isn’t regulated by some government agency. Anyone can claim the title and many do undeservedly. As a rather depressing example, take for instance the small but vocal community of so-called 9/11 skeptics that claim the terrorist attacks were perpetrated by our own government. And even if someone taking a legitimate skeptical stance on a topic is truly closed-minded, it has no bearing on whether their argument is valid. In a similar vein, just because a person arguing that the earth is flat, or some other absurdity, is a certified nut, calling them such is not a rational rebuttal to the claim. The door swings both ways.
In reality, a successful skeptic, at least in the overwhelming majority of instances(1), is the polar opposite of closed-minded. Open mindedness is, in fact, a bedrock foundation of the practice of skepticism. Like science, skepticism is a method of interpreting the world around us, and of accepting a claim only based on reason and the best evidence at their disposal, and then only provisionally. A skeptic is comfortable withholding judgement until such evidence is proffered, and ready to adjust any conclusion as better evidence becomes available.
In a general sense, it is the true believer and not the skeptic that has shut their mind against the interference of reality with their deeply held conviction. As QualiaSoup so succinctly explains in his brief but brilliant video on the subject of using a call for open-mindedness as an argument in support of a belief, open-mindedness is really just code for “agree with me!”.
Skeptics may dedicate their lives to speaking out against a variety of belief systems, from alternative medicine to zermatism, but at heart we would love for a lot of it to be true. Although I feel that the natural world holds more wonder than anything that could be thought up by the likes of Sylvia Brown, Deepak Chopra, or Betty Hill, I still daydream about alien crafts landing on the White House lawn or being able to send objects hurling across a room with merely a thought. Just don’t expect a leap of faith when it comes to acceptance of any claim. A good skeptic is open-minded by definition, but as physicist Richard Feynman warned, not so open-minded that their brain falls out.
(1) Nobody is perfect. Even the most staunch of skeptics can have that one compartmentalized woo nugget squirreled away in their oversized cortex. Not me though. And if you don’t believe me, just ask my psychic 10,000 year old Atlantean spirit guide.