Three Hypotheses of Human Interface Design

"I'm calling these hypotheses instead of laws because they have yet to be proven out through rigrous scientific study and critique. I've developed them merely from anecdotes and examples. However if these hypotheses survive the harsh critiques of PhDs with larger brains (and attention spans) who subject such assertions to sufficient controlled (reproduceable) experiments, then perhaps future generations may see fit to call them 'laws'." (Thanks Daring Fireball!)