Scientists who research the sense of taste divide people into three categories: nontasters, medium tasters and supertasters. These classifications are based on the perception of a compound known as 6-n-propylthiouracil (PROP, for short), which has a bitter taste that is perceptable to some, but not all, people. 25% of people, the nontasters, will register nothing when they taste the compound. To 50% of the population, the medium tasters, PROP will taste bitter, but not overly so. The remaining 25% of people are classified as supertasters and to them, the compound will taste intensely bitter. The classification of "super taster" does not mean that one's sense of taste is superior to another's, but that there is an increased level of sensitivity to various tastes on the tongue.

Supertasters have a much higher density of papillae, the small mushroom-like structures on the tongue that house taste buds, than medium and nontasters. Women are more likely to be supertasters than men are.

There are several ways to determine if you are a supertaster without befriending a scientist. The easiest, though least reliable, way is to take the online quiz that guesses based on your food preferences. A more reliable way is to use a cotton swab to apply blue food coloring to the tip of your tongue, covering at least 1/2 inch. Rinse your mouth gently with water. Place a plastic binder reinforcing ring (or punch a 7-mm hole in a piece of paper) over the blue area and count the pink bumps. The papillae will stay pink while the rest of your tongue is blue, so they will stand out. You are a nontaster if you count fewer than 10 and if you have approximately 30 or more, you are a supertaster. If you do not wish to dye your tongue blue, you can certainly judge whether your are more or less sensitive to taste by simply looking at the density of papillae on the tip of your tongue, though they are much easier to see against a blue background. If you scroll down at this page, you can see examples of different taster's tongues and their papillae.

Supertasters are more likely to dislike and avoid foods they perceive as bitter, like salad greens, raw vegetables, grapefruit, dry wines and tonic water, but just avoiding these types of food does not make you a supertaster, nor will all supertasters avoid these foods. Many people simply have food dislikes, regardless of the number of taste buds that they have. Additionally, though people are born with a predetermined number of taste buds, the sensitivity to PROP and other tastes can decline with age. People can also learn to appreciate other aspects of tastes that they don't initially find pleasing or they learn to mask them, such as adding cream and sugar to strong coffee.