universal principles of design - william lidwell, kritina holden, jill butler 125 laws, guidelines, biases, general considerations selected from variety of disciplines based on things like utility, degree of misunderstanding, strength of evidence 80/20 rule high amount of effect determined by small amount of causes advance organizer instructional technique helping people understand new info in terms of known info mostly for linear teaching, more abstract than overview/summary two types: expository and comparative eg explaining what a forklift is, general function, is for before showing how to operate it eg comparing the features of two forklifts before showing how to operate it aesthetic-usability effect studies suggest people perceive nice looking things as easier to use (and more likely to be used) affordance characteristics (eg physical) which influence function/performance eg round wheels better afford rolling than square eg pushable door should be given flat plate not graspable handle because handle affords graspable, but this conflicts with the non-affordance of swinging in (something like an issue of consistent paths) cathedral effect ceiling height influences cognition high ceilings abstract and lingering, low detailed and quicker closure people tend to perceive things as existing in a pattern subconsciously participate in completing patterns common fate elements that move in the same direction are perceived as more related control level should be matched to the proficiency of users desire lines worn in paths of use (like worn paths in grass fields) or strains on wrists when typing in bad ergonomic positions be mindful of expectations and possible errors exposure effect neutral things become more likeable with repetition (10+ ish) face/body ratio more visible face compared to total head and body is seen as more intelligent, dominant, ambitious personality and intelligence ------- physical forgiveness design to avoid errors or minimize bad effects when they occur horror vacui tendency to fill blank space with objects inverse relationship between emptiness and perceived value (less stuff --> more expensive) inverted pyramid presentation technique critical stuff first and concise, general less important stuff later mental model how a system is represented in a users thoughts, based on experiences modularity (and api) nudge subtle influences of behavior (eg fly picture in toilet bowl to encourage peeing toward it) performance vs preference people might like tradeoffs, less optimal performance for better ___ mostly a comment on features being weighted, ranked personas technique, use fictitious user types to guide decision making priming activating certain thoughts to influence later behavior progressive disclosure manage complexity by revealing things when necessary propositional density how many meanings or ideas are suggested relative to the complexity or number of components of the design can try to leverage symbolism rule of 3rds visual breakdown into 9 squares, 4 intersection points scarcity things seem more desirable when perceived to be limited serial position effects order matters visual first has big effect audio last remembered better shaping technique, teach desired behavior by reinforcing increasingly accurate approximations helpful for complex behaviors veblen effect expensive things seem more desirable weakest link can be used as a benefit, like putting in fuses or using crumple zones in cars