Cognitive biases are flaws in how our brain processes information and heuristics are mental shortcuts which are not always true. For example, we’re more likely to buy something that costs $19.99 rather than $20.00 due to our leftmost digit bias. Handedness bias makes right-handed people prefer the item on the right (and left-handed people the item on the left) when two similar items are presented. An example of framing bias is that we prefer something with a 90 percent survival rate over something with a 10 percent death rate, even though these are both the same. We also take bigger risks to avoid negative outcomes than to achieve positive outcomes.

The gambler’s fallacy is the belief that past events influence future events. We might think a coin that got heads five times in a row would have a better chance of getting tails on the next flip, however, it actually still has a 50 percent chance of being heads.

We are biased in favor of ourselves and our in-group. Also, when we buy something, we think it’s better than it really is because we want to justify the purchase to ourselves. Projection bias is when we assume others think the same way we do. Once the outcome of something is known, we think that it was inevitable even if it was a close call due to hindsight bias.

If we can think of an example of something, we think it must be common even if it’s not. This is called the availability heuristic. We think something belongs to a category if it matches features of that category, even if the category is rare and the thing can fit other more common categories. This is know as the representative heuristic. Unit bias is our tendency to judge something based on a single feature. For example, in one study, people asked to estimate someone’s weight focused on girth but ignored height.

The anchoring heuristic is often used in marketing. If you open negotiations with a high number, it convinces people to pay more than if you start with a lower number. You can convince someone to buy something for $20 if you start by asking for $100 rather than starting out asking for $20.

Confirmation bias is the tendency to interpret new information in support of a previously held belief. In other words, you count the hits but not the misses. This is done unconsciously. For example, a man might insist he always puts the toilet seat down while his wife insists he always leaves it up. This is because the man puts the toilet seat down every time he remembers to put it down, but doesn’t remember the times he forgets. From his point of view, he always puts it down. From the woman’s point of view, he always leaves it up because she only remembers the times when it’s up.

Acupuncture is only about a hundred years old, but practitioners claim it’s thousands of years old to make people believe it works. This is called an appeal from antiquity, but just because something is old, doesn’t necessarily make it better.

The appeal to nature is the belief that natural is better, but just because something is natural doesn’t mean it’s good for us. Many plants are poisonous, for example. The most toxic substance known is botulinum toxin which is all natural. The vast majority of food has been tinkered with by humans for hundreds or thousands of years so most of what we eat isn’t natural. Vitamin C found in nature and Vitamin C created in a lab are exactly the same. One isn’t inferior because it’s artificial. The organic food industry considers highly toxic pesticides such as copper sulfate and rotenone okay because they are “natural”, but this is just a marketing ploy. Natural isn’t automatically better than artificial. It’s even worse in many cases.

The organic industry claims GMOs (genetically modified organisms) are less safe because they aren’t natural, however pretty much all food we eat has already been modified by cultivation, cross-pollination, mutation breeding using radiation or chemicals (which is considered organic farming for some reason), or hybridization. Raspberries are one of the few things which haven’t been genetically modified by humans over the years. The organic industry claims it’s unnatural to put a fish gene in a tomato, but fish and tomatoes share 60 perfect of their genes already. There’s really no such thing as a “fish gene”. It’s all just genes. In reality, GMOs are just as safe and natural as organic food. They’re actually safer since they’re tested more extensively. Also, directly modifying a handful of genes introduces less uncertainty than modifying thousands of genes at once which is what organic farmers do during mutation breeding.

The fundamental attribution error is when we think other people’s actions are caused by their personality, but our own actions are due to external factors beyond our control. We should never assume things about other people since we don’t know everything that’s happened to them. We should always strive to give others the same benefit of the doubt we give ourselves.

Anomaly hunting is looking for anything out of the ordinary and assuming it’s evidence for your pet theory. For example, there was a man holding a black umbrella when JFK was assassinated even though it wasn’t raining. Conspiracy theorists think he was involved because he’s an anomaly. However, he did it as a protest of appeasement policies, which was something people used to do immediately after World War 2, but less often by the time the JFK assassination occurred.

You can find anomalies anywhere if you look hard enough. Don’t confuse randomness or coincidence with your theory. Also something may seem like an anomaly when it’s not. Something related to this is the lottery fallacy. When someone wins a lottery, we might ask what are the odds of them winning which would be something like one in a million. However, the question we should be asking is what are the odds of anyone winning which is basically 100%.