THE TONGUE MAP...

As I mentioned in today's Facebook post (Facebook.com/pairteas), I was browsing through a book about tea that had emerged during my house cleaning. The authors presented a tongue map, stating that, because tastebuds can respond to different tastes, "you can create a tongue map."

The existence of a tongue map such as the one in the book I found is derived from a misinterpretation of the following figure:

This image was compiled from illustrations in a paper by David P. Hänig* about tongue perception and sensitivity to these four flavors.

Here's what Hänig did: with the participation of seven of his colleagues, he put tiny amounts of solution on eight different parts of the tongue and mouth to determine where each tastant could be experienced.  His colleagues tasted each of these solutions everywhere in the mouth except in the middle of the tongue and under the tip. Hänig even tried the uvula and tonsils, though didn't get data from some of his participants at these locations because they gagged! But those who didn't gag could taste the sweet, bitter, sour, and salty in those locations as well.

The drawings above correspond to the results Hänig obtained from five colleagues who gave the intensity of the sensations. The presence of dots indicates that the tasting was perceived in that location, while the closeness of the dots corresponds to the intensity of the sensations. For example sweet was most intense at the tip of the tongue, but could be tasted everywhere except in the middle of the tongue where there are few if any taste buds.

I think it is easy to misunderstand this diagram, given the artistic conventions of the turn of the Twentieth Century. Shading was represented by dots, so in a regular drawing of the tongue the edges  would have had more dots than the middle, to indicate the shape of the tongue. People probably interpreted the less closely spaced dots simply as shading and the dark areas where the dots blend into each other as the locations where each of the tastants could be perceived.

Hänig's paper is fascinating in more ways than this. In my next post, I will discuss how he anticipated  the interactions among salt, sweet, and savory discussed in yesterday's post.

* You can see and download the paper here:  Hänig, David (1901). Zur Psychophysik des Geschmackssinnes. Philosophische Studien 17: 576–623.