Seven lumps of sugar, that's as much as 26 grams. Nevertheless, we say no to a glass of soda quicker if we know how many lumps it contains. This was found by research by Christophe Lembregts from RSM. Lembregts suspects that it has to do with an age-old evolutionary system that seems to be present from birth. People and many animals seem to judge the sizes of collections on visual elements. In other words: 'five fingers' instead of 'five'.