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User Interface Design CS208-5 1 how is assignment 1 coming? due Thursday in class any questions? handing out assignment 2 Thursday any other questions? today critical path scheduling — more next semester start UI design administrivia User Interface Design CS208-5 2 working with schedules assume a list of tasks, times & dependencies discuss where they come from next semester need to use that data to understand project easier to look at pictures than list of data User Interface Design CS208-5 3 gantt charts one graph in common use is gantt charts similar to horizontal bar chart each line describes one task each line’s length is length of time line starts at tasks starting point (and ends ...) User Interface Design CS208-5 4 gantt chart example Task 1 8 15 22 29 6 13 20 27 3 10 17 24 1 A B C D E F G H I J User Interface Design CS208-5 5 gantt chart black box shows (partially) completed grey box shows expected remaining time good for tracking progress against schedule can define tasks as per person to check loading can show dependencies gets hard to see progress User Interface Design CS208-5 6 pert charts PERT charts are alternative Program Evaluation Review Technique developed in 50’s by USN to track polaris sub focuses on dependencies each task is box length of box is proportional to time estimate arrow drawn from box to box depending on it User Interface Design CS208-5 7 sample pert chart B A H D C F E G I J User Interface Design CS208-5 8 critical path CPM (Critical Path Method) usually displayed as Pert chart sometimes Gantt chart what tasks cannot take longer without changing the end date many tasks are not on critical path focus on critical path User Interface Design CS208-5 9 critical path B A H D C F E G I J User Interface Design CS208-5 10 critical path critical path changes as understanding changes if some task slips and/or some task moves ahead the critical path changes lets look at progress against schedule from gantt chart User Interface Design CS208-5 11 gantt chart example Task 1 8 15 22 29 6 13 20 27 3 10 17 24 1 A B C D E F G H I J User Interface Design CS208-5 12 adjusting critical path assuming we are starting week 2 task A is on schedule task C is behind schedule task F is ahead of schedule lets shorten F by week, but add week to C User Interface Design CS208-5 13 critical path B A H D C F E G I J F C D E User Interface Design CS208-5 14 adjusting schedule if one task slips other similar tasks may be optimistic lets extend E by a week as well User Interface Design CS208-5 15 critical path B A H D C F E G I J User Interface Design CS208-5 end of cpm any project management/schedule program should do all of this automatically any questions on schedules/cpm? 16 User Interface Design CS208-5 17 so far worried about requirements defines the problem to be solved time to work on solving that problem focus on design for the remainder of semester design User Interface Design CS208-5 18 requirements say that user is central user interfaces must also be central too often done as an afterthought should be done up-front helps drive system design partially driven by system design user interfaces User Interface Design CS208-5 19 interface is first thing potential customer sees ui averages about 50% of code base ui decisions can be life/death aegis missile therac disaster ui is important User Interface Design CS208-5 20 user interface has 3 goals ease of learning efficiency of use aesthetic appeal balance of 3 given by requirements more of each one good may be at odds at times ui goals User Interface Design CS208-5 21 what is often meant by ease of use mostly aimed at new users helps experienced users expand usage how? affordances consistency clear explanations metaphors ease of learning User Interface Design CS208-5 22 how productive is user? largely determined by user interface also impacted by performance need to know user well mostly for experienced users how? few actions minimal effort actions low mental load efficiency of use User Interface Design CS208-5 23 looking nice helps sales users feel good developers feel good how? read tufte if I knew, I would be teaching art ... aesthetically pleasing User Interface Design CS208-5 24 spiral development especially important for ui no one gets it right the first time many, many iterations often needed remember spiral background to understand today design/eval thurs spiral development understand problem design solution evaluate implement User Interface Design CS208-5 25 to understand user needs must understand user use model human processor Card, Moran and Newell (1980) developed at CMU empirically derived/verified broadly user in UI community cognitive background User Interface Design CS208-5 26 abstracts human cognition very “cpu-like” model “processor” divided into 4 pieces perceptual cognitive long term memory motor model human processor User Interface Design CS208-5 27 model human processor long term memory cognitive short term memory perception motor User Interface Design CS208-5 28 2 perceptions considered auditory visual radical interfaces may require new effort touch, smell, taste auditory and visual handle information in chunks have working memory each has unique features perceptual User Interface Design CS208-5 29 remembers about 17 images very short term (~200 msecs) processes movement, gross patterns first spatial sense is broad focal sense is small (~6 degrees) encodes many aspects into chunks font, color, letter, size, texture, shape, ... visual perception User Interface Design CS208-5 30 remembers about 5 sounds moderate term (~1.7 secs) learns to ignore similar sounds auditory perception User Interface Design CS208-5 31 after perception, chunks can be transferred to cognitive working memory you notice it transferred to long term memory if you are busy/distracted forgotten if you are overwhelmed by sensations processing perceptions User Interface Design CS208-5 32 cognitive processing is thinking also chunk based chunks are variable sized can be perceptions can be ideas can be memories cognitive User Interface Design CS208-5 33 attached to cognitive processing the brain’s register set contains about 7 chunks lasts about 7 seconds without effort thinking about the chunk “refreshes” it working memory User Interface Design CS208-5 34 cognitive processing is rule based patterns from long term memory match chunks in working memory takes about 70 msecs varies widely by task recently accessed rules faster to match when hurrying, will take partial matches cognitive processing User Interface Design CS208-5 35 effectively unbounded in time and space your brain never “fills up” you never truly forget completely memories stored relative to context “forget” details that are expected restored during recall introduces errors long term memory User Interface Design CS208-5 36 recall is inconsistent time varies success rate varies largely vary together depends on encoding when stored depends on uniqueness relative to retrieval “clues” depends on associations almost google-like long term memory User Interface Design CS208-5 37 motor control initiated by chunks in working limited speed and accuracy muscle memory trained by repeated actions increases accuracy allows “higher level” commands motor User Interface Design CS208-5 implications discuss implications on all this and other background on thursday then on to evaluation of interfaces 38
