Human-Computer Interaction. Human perception, attention, memory. Visual perception. Humans capable of obtaining information from displays varying considerably in size and other features but not uniformly across the spectrum nor at all speeds. Theories.
Human perception, attention, memory
Donald A. Norman, The trouble with UNIX: the user interface is horrid. Datamation, 27(12), 139-50, November 1981.
-- extended critique of UNIX commands