Saturday, February 20, 2016

MORE about HÄNIG's STUDIES & WHAT PARTICIPANTS SAID

In yesterday's post I talked about the misinterpretation of the tongue illustrations by David P. Hänig, that led to the development of the erroneous "tongue map." 

In his 1901 paper,* Hänig described a whole series of experiments he performed using his colleagues as participants with the goal of understanding the nature of taste and taste sensitivity.

Some of his other observations are quite remarkable. For example, he was the first to observe that we are far more sensitive to bitter than to the other tastes. Further, our sensitivity to salty is twice that to sweet, but an order of magnitude less than our sensitivity to sour, and three orders of magnitude less than our sensitivity to bitter.

One of Hänig's major concerns was to discover whether there are more than four basic tastes. He was particularly curious to know whether there metallic sensations could be a basic taste, and came to the conclusion that he could not tell. This is a matter of dispute to this day!

In the process of trying to find out the answer to the question of whether the taste of alkali could be one of the basic tastes, Hänig gave his participants tastes of a sodium hydroxide and a potassium hydroxide solution and asked them to describe what they experienced.  He gave quotes from them in his paper. 

Here's one of these quotes (translation mine):
"Salty is prominent, but there is something else with it. Salty, perhaps also sweet and savory with it. It can be a mixture of salty, savory, and sweet. Burning and pricking savory sweet."
He was this close to identifying what we now know as umami!!! 

Here's another quote: 
"Strongly salty, then after that bitter. Salty and bitter—pulling together. A very peculiar experience, I'll recognize it again anytime. One must have the experience, I can't describe it completely."
And the third:
"Primarily salty, perhaps also a bit sweetish and burning. After rinsing the mouth, definitely sweet. It isn't pure salt, ja, how can I express it."
Hänig was clearly frustrated by his participant's inability to describe experience. However, the concept of four basic tastes, derived from the ancient Greeks, dominated his thinking. He was puzzled, but concluded that the experience of these alkaline compounds represented the result of the nervous system combining the four basic tastes.

With this research, Hänig earned his PhD in Leipzig under the guidance of Wilhelm Wundt (1832–1920), considered by many the father of modern psychology. Wundt believed that you could study the human mind through introspection and evaluation of the conscious experience. Wundt had been a student of Hermann von Helmholtz (1821–1894), from whom he received a thorough background in experimenting with sensory perception from a physicist's point of view—Helmholtz had applied physics to the study of vision, hearing, and nerve conduction with some success. Wundt tried to carry out his experiments in this vein.

But taste and smell proved impervious to the Helmholtzian style of analysis. Furthermore, you tend to find what you look for. Wundt and Hänig came to their research with the concept of four basic tastes, and so Hänig's experiments involved primarily these basic tastes, with a side-excursion into the experience of alkali. No savory sensations to experience, except by chance.

It's worth noting here that another of Wundt's students, Edward Bradford Titchener (1867–1927), became a professor at Cornell University (where I worked for most of my career). He developed largest research program in psychology at the time, and mentored the the first woman graduate student in psychology in the US, Margaret Floy Washburn (look her up!). 

Margaret Floy Washburn. Image from Wikipedia.

At Cornell Titchener continued Wundt and Hänig's work on sensory perception. His widely used and influential college textbook "An Outline of Psychology" (1896) was instrumental in reinforcing the idea here in American that there were only four basic tastes, another one of these myths.

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

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