Blind Wine Part I: The Experiment

Already relaxed on his first day in Napa, Brutus and his wife Suzy decide to visit their favorite winery just before lunch to taste their new Cabernet Sauvignon. The owner recognizes them as they walk in the door and immediately seats them on the patio overlooking the vineyard. Two glasses appear, and as the owner tells them about the new Cabernet, Brutus prepares for an onslaught of blackberry and plum flavors, with some notes of vanilla and leather.

The wine is poured and as Brutus swirls it in his glass and breathes in the aromas, he picks up some of the oak infused into the wine as it aged in barrels in a cellar beneath where he sits. He takes a first sip, and, ignoring the obvious blackberry and plum flavors, he searches for the vanilla and leather. He has little difficulty finding them. As a second sip fills his mouth, he asks the owner if maybe he is detecting some chocolate...the owner pours a glass for himself and after a couple of sips agrees with Brutus.

Brutus, a Minitab employee, is an experienced wine drinker who has no doubt experienced many wine tastings not altogether different from what was described above.

But what if the tasting were a little different? What if...

One Thursday afternoon, at the time listed in his Outlook calendar, Brutus enters a conference room and is asked to sit at the table and place a blindfold on. A tasting of wine is poured, and Brutus is asked to tell the experimenters whether the wine is red or white, and which of four types it is. The experimenters don't tell him anything about each wine before it is poured, and offer no information after each tasting. When he is done he takes his blindfold off and goes back to his desk to continue working.

In the absence of visual senses and being "primed" to expect certain flavors, can Brutus, who at the winery could detect even subtle flavor notes in a wine, determine even the most basic information about the wines?  It seemed like a question that could be settled by collecting a little data and looking at it with statistical software.

Fellow blogger Daniel Griffith and I performed this exact experiment and this week we will present the results in a series of blog posts:

• Part I: The Experiment (you're reading it now)
• Part II: The Survey
• Part III: The Results
• Part IV: The Participants

To run the experiment, we first recruited volunteers—all Minitab employees whose names have been changed in the posts—and asked them to complete a survey consisting of four questions:

1. On a scale of 1 to 10, how would you rate your knowledge of wine?
2. How much would you typically spend on a bottle of wine in a store?
3. How many different types of wine (merlot, riesling, cabernet, etc.) would you buy regularly (not as gifts)?
4. Out of the following 8 wines, which do you think you could correctly identify by taste?
   • Merlot
   • Cabernet Sauvignon
   • Pinot Noir
   • Malbec
   • Chardonnay
   • Pinot Grigio
   • Sauvignon Blanc
   • Riesling

We were looking for a broad range of responses, especially to question #1. Once we had enough surveys collected (13), we scheduled the tasting for each participant, with either 2 or 3 being served at any one time. The order of the wines was randomized independently for each participant, but only within each replicate, as we served each participant each of the four wines twice. In other words, a participant would have been given each of the four wines once before ever getting a second tasting, although this was not explained to participants.

The four wines selected were meant to satisfy the following criteria:

• Two red wines and two white wines
• Common enough types that a regular wine drinker would be familiar
• Different enough types that they should be easily distinguishable if tasted back-to-back

Utilizing several resources including those found here, here, and here, we determined the following types to be good choices for the experiment:

• Pinot Noir
• Cabernet Sauvignon
• Riesling
• Sauvignon Blanc

"Representative" bottles of each were purchased in the $15-20 price range, and the bottles were labelled "A," "B," "C," and "D," and otherwise masked so even the experimenters would not know which type of wine they were serving each participant (although color would be obvious).

So how do you think our participants did?

Photograph of Napa Valley by Aaron Logan. Used under Creative Commons License 1.0.