- George Howell: How then, class, can we classify taste sensitivity? Now, we'll talk about that for a moment. Most psychologists have accepted the fourfold Hans Henning classification of 1916; the four tastes being bitter, sweet, sour, and salty, incidentally in order of equity. But, for 20 years, a man named Wundt--W-U-N-D-T--believed that there was a fifth taste, and he called it metallic. But he did finally give it up. Now, his reasons for abandoning this theory aren't really known. He probably changed dentists or something!