Why people fall for misinformation - Joseph Isaac

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In 1901, David Hänig published research that led to what we know today as the taste map: an illustration that divides the tongue into four separate areas. It has since been published in textbooks and newspapers. There is just one problem: the map is wrong. So how do misconceptions like this spread, and what makes a fake fact so easy to believe? Joseph Isaac dives into the world of misinformation.

Lesson by Joseph Isaac, directed by CUB Animation.

In 1901, David Hänig published a paper

that forever changed
our understanding of taste.

His research led to what we know
today as the taste map:

an illustration that divides the tongue
into four separate areas.

According to this map,

receptors at the tip of our tongues
capture sweetness,

bitterness
is detected at the tongue’s base,

and along the sides, receptors capture
salty and sour sensations.

Since its invention, the taste map
has been published

in textbooks and newspapers.

The only problem with this map,
is that it’s wrong.

In fact, it’s not even
an accurate representation

of what Hänig originally discovered.

The tongue map is a common misconception—

something widely believed
but largely incorrect.

So where do misconceptions
like this come from,

and what makes a fake fact
so easy to believe?

It’s true that the tongue map’s
journey begins with David Hänig.

As part of his dissertation
at Leipzig University,

Hänig analyzed taste sensitivities across
the tongue for the four basic flavors.

Using sucrose for sweet,
quinine sulfate for bitter,

hydrochloric acid for sour,
and salt for salty,

Hänig applied these stimuli to compare
differences in taste thresholds

across a subject’s tongue.

He hoped to better understand
the physiological mechanisms

that affected these four flavors,

and his data suggested that sensitivity
for each taste

did in fact vary across the tongue.

The maximum sensation for sweet
was located at the tongue’s tip;

bitter flavors were strongest at the back;
salt was strongest in this area,

and sour at the middle
of the tongue’s sides.

But Hänig was careful
to note that every sensation

could also be tasted across the tongue,

and that the areas he identified offered
very small variations in intensity.

Like so many misconceptions,

the tongue map represents a distortion
of its original source,

however the nature of that distortion
can vary.

Some misconceptions
are comprised of disinformation—

false information intentionally designed
to mislead people.

But many misconceptions,
including the tongue map,

center on misinformation—
false or misleading information

that results from unintentional
inaccuracy.

Misinformation is most often shaped
by mistakes and human error,

but the specific mistakes
that lead to a misconception

can be surprisingly varied.

In the case of the tongue map,

Hänig’s dissertation was written
in German,

meaning the paper could only be
understood by readers fluent in German

and well versed in Hanig’s
small corner of academia.

This kicked off a game of telephone
that re-shaped Häing’s research

every time it was shared
with outside parties.

Less than a decade after his dissertation,

newspapers were falsely insisting
that experiments

could prove sweetness was imperceptible
on the back of the tongue.

The second culprit
behind the tongue map’s spread

were the images
that Hänig’s work inspired.

In 1912, a rough version of the map
appeared in a newspaper article

that cautiously described
some of the mysteries

behind taste and smell research.

Featuring clear labels across the tongue,
the article’s illustration

simplified Hänig’s more-complicated
original diagrams.

Variations of this approachable image
became repeatedly cited,

often without credit or nuanced
consideration for Hänig’s work.

Eventually this image spread
to textbooks and classrooms

as a purported truth
of how we experience taste.

But perhaps the factor that most
contributed to this misconception

was its narrative simplicity.

In many ways,

the map complements our desire for clear
stories about the world around us—

a quality not always present
in the sometimes-messy fields of science.

For example,

even the number of tastes we have is more
complicated than Hänig’s work suggests.

Umami— also known as savory—
is now considered the fifth basic taste,

and many still debate
the existence of tastes

like fatty, alkaline, metallic,
and water-like.

Once we hear a good story,

it can be difficult to change
how we see that information,

even in the face of new evidence.

So, next time you see a convenient chart
or read a surprising anecdote,

try to maintain a healthy skepticism—

because misconceptions
can leave a bitter taste

on every part of your tongue.