Research in the US suggests the colour of wine affects how much we drink. Photo: iStock
Participants in a study by researchers at Iowa State University in the United States were asked to pour what they considered a normal drink using different types of glasses in various settings.
When pouring white wine into a clear glass they were found to pour nine per cent more than when pouring red, which had a greater colour contrast to the glass.
They also poured around 12 per cent more wine into a wide glass than a standard one.
The influence of the wine colour and glass type could have serious consequences for drinkers' health, the researchers warned.
Dr Doug Walker, lead author of the study, said: "If you ask someone how much they drink and they report it in a number of servings, for a self-pour that's just not telling the whole story.
One person's two is totally different than another person's two. Participants in the study were asked to pour the same amount at each setting, but they just couldn't tell the difference."
The findings, published in the journal Substance Use & Misuse, were said to demonstrate the need to educate people about how to measure a proper serving size of alcohol.
The study found that the design of a wine glass and the way it is held can also determine how much alcohol drinkers consume.
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Just as environmental cues such as plate size and food labels have been shown to affect eating behaviours, so the size and shape of a glass can cause drinkers unintentionally to pour larger amounts than they intended to.
When the receptacle is wider than a traditional glass, or is being held rather than on a table, or matches the colour of the wine, drinkers are inclined to consume more, researchers found.
To examine the effects of glass position, respondents either poured their wine into a glass they were holding or into one placed on a table.
To examine the visual effects of colour contrast, there was either low contrast between the wine and the glass (white wine in a clear glass) or high contrast (red wine in a clear glass).
When glasses were wider, participants poured 11.9 per cent more, researchers found. Respondents poured 12.2 per cent more wine when they were holding their glasses, compared with into glasses that were placed on a table.
When there was low contrast between the glass and the drink (white wine in a clear glass), participants poured 9.2 per cent more than when there was high contrast (red wine in a clear glass).