How many of us have had this ‘tongue map’ presented to us in grade school?
Allow to me elaborate, in case you are unfamiliar. As a child, it was not uncommon to observe demonstrations of the taste senses mapped to specific areas of the tongue. The same experiments seen on “kid science” shows would often be replicated in the classroom setting.
Children would gingerly follow instructions, dabbing Q-tips soaked in aqueous solutions of sugar, salt, lemon juice and unsweetened cocoa on their tongues. Stickers would be placed over a tongue-diagram, which indicated how strongly they sensed the corresponding taste (sweet, salty, sour and bitter) in different areas.
Full marks would be awarded to the students who could replicate the canonical result shown in the comic. Some children would not be able to observe any patterned spatio-lingual mapping of taste, a teacher would likely affirm that their failure to reproduce the canonical map lies in them. The ‘success’ of the former set of children was not due to their refined sense of taste, but rather, some earlier exposure to the experiment and the ability to quietly ignore their own perceptions when it is expected by an authority figure.
The truth is that this map is a complete fallacy. The original paper by Edwin G. Boring in 1901, reported subtle differences in taste sensitivities (not the discrete sensation, as it is often implied in current demonstrations). Virginia Collings took a critical look at this and reported that taste sensitivity is pretty uniform across the tongue…in 1974. A testament to the canard’s tenacity can be seen by looking at a relatively recent Nature paper, where modern biology is used to explicitly map taste receptors and the authors present a diagram whose caption reads: “…contrary to popular belief, there is no tongue map”.
Perhaps I am exaggerating, or even mis-remembering, how the tongue map was presented to me as a child. We’ve long since cleaned up our collective understanding of this basic concept…let’s do a little googling:
Oh, alright..just one website, not too bad.
A University of Washington “neuroscience for kids” website? <-- Their protocol involves toothpicks instead of Q-tips. Bravo.
Et tu, PBS? <--- Apparently an NSF funded website
This is one “experiment for kids” that needs to be repurposed as a demonstration of our embarrassingly fallible perception in the context of perceived authority, and the profound inertia of ignorance.