Wine expert Robert Parker claims to be able to distinguish every wine he has ever tasted—10,000 different wines a year—by taste alone. Winemakers can use their sense of smell to detect slight imbalances early in the wine production process that might lead to a spoiled batch. Meanwhile, novices walk the aisles of the typical wine store in a daze, uncertain of which wine to select and unsure whether paying a premium for a "better" vintage is worth the cost. During the German occupation of France, when winemakers were forced to ship their best wines to Hitler's henchmen in Berlin, they poured thousands of gallons of plonk into fancy bottles, a ruse which went unnoticed until after the war.
True wine experts' superior recognition of the subtle differences between wines over even educated amateurs has often prompted the question perhaps best expressed by The Wizard of Oz's Cowardly Lion: "What do they got that I ain't got?"
Can wine expertise be learned through careful study? Some research suggests that an improved vocabulary to describe different wines (learning how to use terms like bouquet, terroir, and tannin) has helped novices learn to taste the differences. However, other studies have found that an increased tasting vocabulary simply masks weaknesses of the palate. Here's a sampling of what I found on my shelves, which doesn't seem to have helped me much:
If it isn't their superior understanding of wine terminology that helps experts recall the nuances of different wines, then perhaps they simply have superior senses: better noses and taste buds. Another possibility is that experts have superior "semantic memory"— verbal memory of wine terminology associated with a particular sensation. Wendy Parr and David Heatherbell of Lincoln University, and K. Geoffrey White of University of Ontego devised an experiment to determine exactly where the differences between experts and novices lie ("Demystifying Wine Expertise: Olfactory Threshold, Perceptual Skill and Semantic Memory in Expert and Novice Wine Judges," Chemical Senses, 2002 [full text]).
Parr and her colleagues tested 11 wine experts (wine makers, professional wine critics, or wine scientists) and and 11 "novices" (regular wine drinkers with little formal training—typically students with some experience in food science or wine—this group might be considered "intermediate" or even "expert" in some studies. If formal training includes knowing how to open a bottle of wine with a screwdriver and a pair of pliers, then I'd probably be a member of this group).
The first test was simply to determine each participant's odor-detecting ability, using a chemical not found in wine: butanol. Participants sniffed bottles containing tiny traces of the chemical. The proportion of butanol was gradually increased until the participant could reliably distinguish between its odor and that of pure water. On this test, no difference was found between the experts and the novices.
Next, they were asked to identify 11 of 28 possible odor-producing chemicals commonly found in wine, again using just their sense of smell. They were not required to give each compound's chemical name (terms like "ethyl anthranilate," or "5-ethyl-4-methyl-3-hydroxy furanone"), but just the common wine-taster's description of the aroma ("grape-like, foxy" or "caramel, maple"). Again—surprisingly—there was no difference between the expert and novice wine tasters. Each group accurately named each smell only about half the time—so their "semantic memory" appeared to be equal.
Finally, participants were given a set of 22 chemicals (from the original set of 28). They had smelled 11 of them before, but 11 were new, and in each case they were asked whether they had smelled the chemical previously. In this condition, the experts were indeed substantially better than the novices. They were both more accurate at indicating when they had encountered an odor before, and better at detecting a new scent.
Parr et al. suggest that the difference between the experts and novices may be due to the fact that smells are very difficult to describe. Novices may over-rely on linguistic descriptions of odors, which often don't readily correspond to the scents themselves. Experts, with their years of exposure to the aromas of wine, have developed perceptual memories that are able to overcome the deficiencies of language. This distinction might be similar to the way new doctors diagnose illness "by the book," while veterans tend to look at the overall health of the patient to come up with a treatment.
Another way of putting it is that all those verbose descriptions on the backs of wine bottles and in magazines and books may do little to explain the real differences in wines: it's better to simply taste the wines and experience the differences yourself. I'll drink to that!