The Swimmer’s Body Illusion

The dangers of confusing cause and effect

The swimmer’s body illusion is a cognitive bias that makes us confuse results and selection factors.

In other words, we often think that certain results are caused by certain activities, when in fact, people only take part in certain activities because they already have some or all of the results.

A few examples:

• Swimmers’ bodies: A lot of people think that swimming will help them develop long limbs, chiseled abs and broad shoulders. But often, swimmers don’t look the way they do because they swim, they swim because they look the way do. Take Michael Phelps for example. He has a disproportionately longer upper body, double-jointed feet that act like flippers and the wingspan of someone 10 cm taller than him. These all help him to swim faster, and can’t be replicated with any amount of practice.
• Cosmetics ads: Makeup brands hire beautiful models for their campaigns, implicitly telling us that their products can make us look just like them. However, these models are likely beautiful due to some combination of genetics and looking after themselves, rather than the brand of concealer they use.
• Top universities: Harvard has a reputation for being a top university. But this doesn’t necessarily…