In a series of classic studies done in the 1960's, the Swiss developmental psychologist Jean Piaget showed how children can misperceive volume. When colored liquid was poured from a taller cylinder to a shorter wider cylinder, they thought the volume of liquid had decreased. These primary school children were using only the height of the container when making volume judgments and were hence making mistakes. Ah, you say, they are children and are naive enough not to understand that more than height goes into determining the volume of liquid in a container. Full grown adults would never make that mistake. Why, if such height based illusions existed, wouldn't restaurants routinely use tall thin glasses to pour your drinks, rather than short wide glasses? Well.