The shape of your glass is probably the last thing on your mind when you are down the pub.

However, researchers at the University of Bristol believe the shape of beer glasses affects the speed people drink.

Their study, published in the journal PLoS ONE, suggests people drink more quickly out of curved glasses than straight ones.

They argue that the curvy glassware makes pacing yourself a much greater challenge.

A group of 159 men and women were filmed drinking either soft drinks or beer as part of the study. The glasses all contained around half a pint of liquid, but some of the glasses were straight while others were very curved.

Slower pace

There was no difference in the drinking time for soft drinks. People drinking from both straight and curved glasses finished after around seven minutes.

However, for the beer drinkers there was a large difference between the two groups. While it took around seven minutes for people drinking from a curved glass to polish off their half pint, it took 11 minutes for those drinking from a straight glass.

The report said: "Drinking time is slowed by almost 60% when an alcoholic beverage is presented in a straight glass compared with a curved glass."

The researchers thought that curvy glasses made it harder to pace drinking because judging how much was in the glass became more difficult owing to its curved shape.

The group of drinkers was shown a variety of pictures of partially-filled beer glasses and asked to say whether they were more or less than half full.

The team said people were more likely to get the answer wrong when assessing the amount of liquid in curved glasses.

The lead researcher Dr Angela Attwood told the BBC: "They are unable to judge how quickly they are drinking so cannot pace themselves."

She suggested that people were not concerned about pacing themselves with soft drinks, which could explain why glass shape had no effect on them.

However, the study looked only at the time taken to finish one drink in a laboratory setting. So it is not certain what happens on an evening out if multiple drinks are consumed.

She said altering the glasses used in pubs could "nudge" people to drink more healthily by "giving control back".

The shape of a glass has already been shown to affect how much alcohol people pour. A study in 2005 showed people were more likely to pour extra alcohol into short, wide glasses than tall, narrow ones.