Piaget proved wrong again!
http://www.eurekalert.org...j-sgm122105.php
Seems like the grandaddy of developmental psychology over-estimated the competance of everyone over eight years old. At about this age we learn about conservation of volume, in particular that a tall thin glass doesn't necessarily have more in it than a short fat one.. except we often forget when drinks are involved.
Short glasses more likely to lead to over-indulgenceShape of glass and amount of alcohol poured: Comparative study of effect of practice and concentration; BMJ Volume 331 pp 1512-4
make mine a short!