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The shape of a glass can have a significant effect on how much one pours. A Cornell University study of students and bartenders' pouring showed both groups pour more into short, wide glasses than into tall, slender glasses.  Aiming to pour one shot of alcohol ( ounces or ml), students on average poured ml & ml (30% more) respectively into the tall and short glasses. The bartenders scored similarly, on average pouring % more into the short glasses. More experienced bartenders were more accurate, pouring % less alcohol than less experienced bartenders. Practice reduced the tendency of both groups to over pour for tall, slender glasses but not for short, wide glasses. These misperceptions are attributed to two perceptual biases: (1) Estimating that tall, slender glasses have more volume than shorter, wider glasses; and (2) Over focusing on the height of the liquid and disregarding the width.