Heuristics are mental shortcuts we use to make sense of the world.
If I were to ask you what is more common, death by shark attacks or death by hippopotamus attacks, you’d probably answer shark attacks.
This is called the availability heuristic. We are more likely to assume shark attacks are more common because we hear about them more. We can more readily think of instances of shark attacks (thanks “Jaws”), and thus we believe it is more common. (Hippo attacks are actually a lot more common.)
We use these heuristics to lighten the mental load of critical thinking. Usually they make our life easier, but not always. Sometimes these oversimplifications can lead us astray.
Here are a couple common health-related heuristics:
“If it’s natural it’s good.”
Food, medicine, etc. Many people use how “natural” something is as a judgement of how “healthy” it is. This makes sense. All naturally occurring foods are very healthy: fruits, vegetables, meat, and grains. Most of the time this assumption will be right.
However, if you blindly apply the heuristic then you won’t catch the moments when it isn’t true.
Lead is as natural a substance as you can get. Also very not good for you.
Many life-saving cancer treatments are not natural, and yet, I’d be hard-pressed to tell anyone whose life is saved as a result of that treatment that it wasn’t good for them.
“If you can pronounce it, don’t eat it.”
This is an extension of the above heuristic. Many folks believe the chemicals in their food are not healthy, and this heuristic allows them to avoid harmful substances.
Good luck pronouncing that one. Did I mention it’s also reportedly a “superfood?”
These mental heuristics are a shortcut for critical thinking, but they should not be an outright replacement of it.
You still need to be able to make sound judgements. Context matters.
Sometimes, shortcuts make things more difficult.