Everybody has seen the tongue map – that little diagram with different sections neatly cordoned off for different taste receptors. Sweet in the front, salty and sour on the sides and bitter at the back. This is a long-held misconception that the tongue has specific zones for each flavour where you can taste sweet or sour, for example, especially well. But this myth is based on an incorrect reading of an illustration of the tongue. You can still find these zones in many textbooks today.

That familiar but not-quite-right map has its roots in a 1901 paper, Zur Psychophysik des Geschmackssinnes, by German scientist David Hänig. Hänig set out to measure the thresholds for taste perception around the edges of the tongue (what he referred to as the “taste belt”) by dripping stimuli corresponding to salty, sweet, sour and bitter tastes in intervals around the edges of the tongue.

It is true that the tip and edges of the tongue are particularly sensitive to tastes, as these areas contain many tiny sensory organs called tastebuds.

Hänig found that there was some variation around the tongue in how much stimulus it took for a taste to register. Though his research never tested for the now-accepted fifth basic taste, umami (the savoury taste of glutamate, as in monosodium glutamate), Hänig’s hypothesis generally holds up. Different parts of the tongue do have a lower threshold for perceiving certain tastes, but these differences are rather minute.

Sweet, sour, salty, bitter and savoury tastes can actually be sensed by all parts of the tongue. Only the sides of the tongue are more sensitive than the middle overall. This is true of all tastes – with one exception: the back of our tongue is very sensitive to bitter tastes. This is apparently to protect us so that we can spit out poisonous or spoiled foods substances before they enter the throat and are swallowed.

Find more myths debunked at http://www.iflscience.com/ .