By now every sentient being with access to the internet has seen #TheDress.
#TheDress is an optical illusion that relies on varying perceptions of different observers.
The fact that the brain is constantly constructing a model of what the world really looks like is also true for color vision. The fundamental challenge in the perception of color is to identify an object despite changing illumination conditions—how bright or dim the ambient lighting is. The mixture of wavelengths that reaches our eye will be interpreted by the brain as color, but which part is due to the reflectance of the object and which part is due to its surrounding illumination?
In other words, an individual’s perception of the color of the dress is influenced by his or her perception of the ambient light in the photograph. Those who see the dress as blue & black interpret the photo as overexposed, and their brains adjust the colors accordingly. Those who see the dress as white and gold, interpret the ambient light as natural light, and no color adjustment is made.
What can the dress teach us about pseudoscience in general and anti-vaccine advocacy in particular? Quite a bit as it turns out.
1. Context is critically important
Different people look at the same image and see different things, because they perceive the context differently. Those who assume the context is an overexposed photo conclude that the colors in the photo (white and gold) are washed out and adjust them accordingly; the white becomes blue and the gold becomes black. Those who see the context as a normally exposed photo conclude that the colors in the photo are true and no adjustment is made; the white remains white and the gold remains gold.
Context is important in vaccine safety, too.
For example, back in 2011, the pseudoscience blog Age of Autism breathlessly announced that there had been more miscarriage events associated with the HPV vaccine Gardasil than other vaccines. The folks at AofA concluded that Gardasil causes miscarriages and is therefore dangerous.
It’s hardly surprising that Gardasil, the ONLY vaccine given exclusively to women of reproductive age has more miscarriage EVENTS than other vaccines. Was anyone expecting that vaccines given to prepubertal children were going to be associated with miscarriages?
Moreover, the number of miscarriages in meaningless. The only meaningful measurement is the miscarriage RATE (the number of miscarriages divided by the number of pregnant women who received the Gardasil vaccine). And since the natural miscarriage rate is 20%, that number would need to be substantially higher than 20% to merit any concern that Gardasil leads to miscarriage. But of course the AofA article does not bother to calculate the miscarriage rate or to compare it to the natural miscarriage rate.
Anti-vax activists drew a false conclusion because they didn’t understand the context. A vaccine given to small children is never going to be followed by a miscarriage because small children don’t get pregnant. And a miscarriage that occurs after receiving a vaccine tells us nothing about whether the vaccine caused the miscarriage because 20% of women in early pregnancy routinely miscarry.
2. When important pieces of information are missing, the brain will attempt to fill in, sometimes with disastrous results.
The reason that different people see #TheDress as different colors is because the context cannot be determined from the photo itself. There is nothing else in the photo that can help us determine if it is properly exposed or over exposed. In contrast, if there were a zebra in the background of the picture and its colors appeared to be gold and white, we would know that the photo was dramatically over exposed and everyone’s brains would adjust the colors of the dress to blue and black. Because we can’t determine the context, some people’s brains make the erroneous assumption that the light in the photo is natural light and that dramatically affects their perceptions of the colors they see.
In the absence of knowledge of immunology, chemistry and statistics, many anti-vax advocates fill in the missing knowledge with erroneous assumptions. For example, when they heard that mercury was originally in vaccines, they assumed that mercury compounds are exactly the same as elemental mercury; since elemental mercury is dangerous, they assumed that mercury compounds in vaccines were dangerous, too. Had they known more basic chemistry, they would have recognized that elemental sodium is also dangerous (it can explode if it comes in contact with water), but is perfectly safe in the compound sodium chloride, table salt.
Moreover, most anti-vax advocates don’t understand that just because B follows A in time does NOT mean that B is caused by A. The fact that many children were diagnosed with autism in the months after receiving the MMR vaccine led anti-vax advocates to conclude that the MMR causes autism. But autism diagnoses are almost always made after a child learns to walk and that does not mean that walking causes autism.
The human brain likes stories with simple cause and effect and may create those stories when reality is far more complicated.
3. Reality exists independent of what you believe.
#TheDress is blue & black. It may look different to some observers when viewed in an over exposed photo, but the dress itself is still blue & black. Just because it seems to some parents that vaccines injured their children does not mean that any vaccine injury was sustained. Reality exists regardless of whether you perceive it correctly.
4. You can’t always rely on what you see.
This is the most important take away from the photo of #TheDress. You can’t accurately judge the color of the dress unless you know the context and if you don’t know the context, you should be wary of making assumptions about the context. Similarly you cannot judge the safety of vaccines unless you have a solid understanding of basic immunology, chemistry and statistics. You can make assumptions in the absence of that knowledge, but you are more likely to be wrong than to be correct.
Vaccines are one of the greatest public health advances of all time. They have saved tens, perhaps hundreds of millions of lives. They have hurt some children in the process, but the risk of being harmed by the disease is 1000X greater than the risk of being harmed by the vaccine designed to prevent the disease. It doesn’t matter if you perceive vaccines as dangerous. If you lack knowledge of basic immunology, chemistry and statistics, you lack the context to draw accurate conclusions about vaccine safety and your intuition is worthless. After looking at the photo, many people intuit #TheDress as white and gold, but they’re wrong. It’s blue and black; it was always blue and black; and it will always be blue and black no matter that some people cannot perceive the colors correctly.
Vaccines are safe; they were always safe; and they will continue to be safe no matter that some people cannot perceive their safety accurately.
