Decision Making Bias: Common Belief

Learn about the Common Belief bias with exercises.

What is the Common Belief Fallacy?

The concept in one sentence:

If most people believe something is true, you are more likely to believe it is true.

The concept in one quote:

The trouble with the world is not that people know too little; it's that they know so many things that just aren't so.

Mark Twain

The benefit of being aware of the bias:

Understand that even if lots of people believe something is true, it doesn’t necessarily make it true.


The goal of this week’s exercises is to make you aware of the bias.


Examples

Example 1

Where are fortune cookies from?

Answer:

Did you think China?

The exact origin of fortune cookies is unclear, though various immigrant groups in California claim to have popularized them in the early 20th century. They most likely originated from cookies made by Japanese immigrants to the United States in the late 19th or early 20th century.

Source


Exercises

Exercise 1

Does sugar make kids hyper?

  • Yes

  • No

Exercise 2

Did Vikings have horns on their helmets?

  • Yes

  • No

Exercise 3

Do mice like cheese?

  • Yes

  • No

Exercise 4

How many senses do humans have?

Exercise 5

Are alpha wolves real?

  • Yes

  • No

Exercise 6

Do bulls hate the color red?

  • Yes

  • No

Exercise 7

Do people have different learning styles?

  • Yes

  • No

Exercise 8

Are bats blind?

  • Yes

  • No


Answers

Answer to Exercise 1

No.

Sugar does not cause hyperactivity in children. Double-blind trials have shown no difference in behavior between children given sugar-full or sugar-free diets, even in studies specifically looking at children with attention deficit hyperactivity disorder or those considered sensitive to sugar. A 2019 meta-analysis found no positive effect of sugar consumption on mood but did find an association with lower alertness and increased fatigue within an hour of consumption, known as a sugar crash.

Source

Answer to Exercise 2

No.

Viking warriors are associated with horned helmets in popular culture, but there is no evidence that Viking helmets had horns. The depiction of these horned helmets as historical is a fallacy that began in the 1870s. It was part of the construction of great Norse myths to be adopted by Germans, who wanted their own ancestral myths.

Source

Answer to Exercise 3

Not really.

Mice do not have a special appetite for cheese and will eat it only for lack of better options. Mice actually favor sweet, sugary foods. It is unclear where the myth came from.

Source

Answer to Exercise 4

More than 5.

Humans have more than the commonly cited five senses. The number of senses in various categorizations ranges from five to more than 20. In addition to sight, smell, taste, touch, and hearing, which were the senses identified by Aristotle, humans can sense balance and acceleration (equilibrioception), pain (nociception), body and limb position (proprioception or kinesthetic sense), and relative temperature (thermoception).

Source

Answer to Exercise 5

No.

There is no such thing as an "alpha" in a wolf pack. An early study that coined the term "alpha wolf" had only observed unrelated adult wolves living in captivity. In the wild, wolf packs operate more like human families: there is no defined sense of rank, parents are in charge until the young grow up and start their own families, younger wolves do not overthrow an "alpha" to become the new leader, and social dominance fights are situational.

Source

Answer to Exercise 6

No.

Bulls are not enraged by the color red, used in capes by professional matadors. Cattle are dichromats, so red does not stand out as a bright color. It is not the color of the cape, but the perceived threat by the matador that incites it to charge.

Source

Answer to Exercise 7

No.

All humans learn in fundamentally similar ways. In particular, there is no evidence that people have different learning styles, or that catering teaching styles to purported learning styles improve information retention.

Source

Answer to Exercise 8

No.

Bats are not blind. While about 70 percent of bat species, mainly in the microbat family, use echolocation to navigate, all bat species have eyes and are capable of sight.

Source


Messages from Readers

Sometimes the answer isn't universally true but relative to the person.

For example:

Where do you think the price of Bitcoin is going?

  • Up

  • Down

Answer:
Depends on what you're exposed to, your answer will vary depending on if you watch certain news that says it’s going to 0. Vs if you're hanging out with blockchain developers who all say it’s gonna go up.

Demi

A useful text to moderate this notion of "common belief fallacy":

Doxa, Episteme, and Gnosis

Sometimes the public opinion (or Doxa) is useful knowledge to allow us to function in society.

One of the examples cited is "how many senses do we have"?. The common answer (Doxa) is 5: smell, taste, hearing, sight, and touch, while the savant answer (episteme) is "it's complicated", taste and smell are interplaying with each other, while touch is really a "tactile - proprioceptive - kinesthetic" sense. But answering in such a complicated manner to this simple question will just make you look like an ass.

Gordon


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