What Causes Wine Drinkers to Overpour?

iStock_000006055190Small pouring wineWhen pouring wine, have you ever found it hard to assess how much is in the glass? Well, you’re not alone. Researches from Iowa State and Cornell universities have found that wine drinkers unintentionally pour larger servings when their glasses are wider, when they are holding the glasses in their hands, and when there is a low contrast between the color of the wine and the glassware. The study, Half Full or Empty: Cues That Lead Wine Drinkers to Unintentionally Overpour, by Doug Walker, Laura Smarandescu, and Brian Wansink, was published in Substance Use & Misuse.

Researchers tested six factors thought to influence perception of liquid volume by asking participants to pour themselves a normal serving of wine at different stations where environmental factors had been manipulated. (Note: A standard serving of table wine is 5 oz. according to the National Institute on Alcohol Abuse and Alcoholism.) To test the effect of glass size/shape, three types of wine glasses (large, wide, and standard) were used. To test if anticipation of a meal impacted serving size, some stations featured a large or small place setting. To test the impact of pouring position, participants were asked to pour wine into a glass they were holding or into a glass on a table. To examine the impact of color contrast, white wine in a clear glass (low contrast) and red wine in a clear glass (high contrast) were used. Seventy-three individuals, all of whom drank at least one glass of wine per week, participated in the study.

Researchers found that several environmental cues lead to overpouring:

  • Glass width: When glasses were wider, participants poured 11.9% more wine.
  • Pouring position: Participants poured 12.2% more wine when they poured into glasses they were holding as compared with pouring into glasses that were on a table.
  • Color contrast: When there was low contrast between the glass and the wine (white wine in a clear glass), participants poured 9.2% more wine than when there was high contrast (red wine in a clear glass).

After finishing the study, each participant was asked to rate the degree to which they felt each environmental cue impacted the amount of wine they poured. They rated glass width, glass-holding, and color contrast as most influential—the three factors that had resulted in the most overpouring.

So what advice do researchers have for those who want to avoid overpouring? First, be aware that overpouring can happen, and where possible, avoid the conditions that tend to lead to overpouring. So use taller, narrower glasses, put your glass on the table before pouring, and select wines with colors that contrast with the color of your glassware.

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