cartographers must learn cognitive psychology and ergonomics to understand which symbols convey information about the earth most effectively, and behavioural psychology to induce the readers of their maps to act on the information. they must learn geodesy and fairly advanced mathematics to understand how the shape of the earth affects the distortion of map symbols projected onto a flat surface for viewing. it can be said, without much controversy, that cartography is the seed from which the larger field of geography grew. most geographers will cite a childhood fascination with maps as an early sign they would end up in the field.