Which has more?

New Delhi, Jan. 1: This take-home message from consumer behaviour researchers will outlast the New Year festivities: whether you’re pouring whisky, beer or orange juice, the shape of the glass might influence how much you consume.

Research by marketing specialists investigating factors that influence consumption show that people wrongly estimate that tall or elongated glasses or other containers hold more than short, wide glasses of the same capacity.

A study in the US involving 198 college students at the University of Illinois, Urbana-Champaign, and 86 bartenders in Philadelphia has found that both college students and even experienced bartenders poured more drink into short, wide glasses than into tall, elongated glasses.

The college students and the bartenders were asked to pour 44.5 ml, the amount regarded as the established standard for a single drink. While the students poured 30 per cent extra, the bartenders poured 20 per cent extra drink into short, wide glasses, Brian Wansink, professor at Cornell University, and his co-author said, reporting their findings in the current issue of the British Medical Journal.

In a previous study two years ago, Wansink and his co-worker Koert van Ittersum at the Georgia Institute of Technology in the US had shown that adults poured 28 per cent more breakfast juice into short, wide glasses than into tall ones with the same volume.

The researchers believe that the extra pouring stems from “perceptual biases” ? people assume that tall glasses hold more liquid than wide ones of the same volume and, while pouring, they turn their attention to the height of the liquid in the glass, without compensating for the width of the glass.

“The better way to control alcohol consumption would be to use tall glasses or to use glasses with levels marked on them ? and to realise that, when alcoholic drinks are served in a short wide glass, two drinks are actually two and a half,” they said.

Another set of independent studies by Priya Raghubir, an associate professor at the Hass School of Business, University of California, Berkeley, also suggest that volume perception biases among consumers affect their decisions on how much to consume.

Raghubir, an alumnus of St. Stephen’s College in New Delhi and the Indian Institute of Management in Ahmedabad, has conducted research on visual information processing and consumer behaviour.

In a paper set to appear in a forthcoming issue of the Journal of Retailing, Raghubir and her colleague Sha Yang, assistant professor at New York University, have shown that elongated containers are perceived to contain more even when labels mention the actual volume of the container.

One study indicated that beer bottles are perceived to contain more than beer cans, particularly by infrequent drinkers. Another study showed that the purchase quantity of cans was higher than the purchase quantity of bottles.

Researchers believe such studies would benefit both consumers as well as product manufacturers who might seek to package products to maximise sales.