Users do not see your interface. They see the parts of your interface that are relevant to their current goal. Selective attention is the cognitive process by which the brain filters a continuous stream of sensory input, directing full processing resources toward stimuli aligned with current goals while suppressing everything else. The cocktail party effect, your ability to hear your name spoken across a noisy room while filtering out dozens of simultaneous conversations, is a classic demonstration. Daniel Simons and Christopher Chabris's 1999 invisible gorilla experiment extended this to visual attention: participants asked to count basketball passes missed a person in a gorilla suit walking through the scene.