Information Systems Analysis and Design csc340 XXIV User Interface Design What is Human Computer Interaction Affordances Mappings Mental Models Feedback Forcing Functions Learning How to Design Interfaces User Dialogue Design Inputs and Outputs 2001 Marilyn Mantei and John Mylopoulos Interface Design 1 Information Systems Analysis and Design csc340 HCI Human Computer Interaction Why should a Systems Analyst Know HCI n 40 60 of today s software does user interface management high interactivity with the user much end user programming n User interactivity is only going to get more complex 3D graphics and Virtual Reality More augmented reality activities n Many of the problems with introducing and maintaining a system can be traced back to a bad interface design Users sabotage systems they don t understand Users make more errors when dealing with systems that are difficult to use n A good user interface can reduce coding costs reduce high costs of interface problems reduce serious life threatening errors sell more products lead to increased use of computers 2001 Marilyn Mantei and John Mylopoulos Interface Design 2 Information Systems Analysis and Design csc340 Increased Productivity X X X 20 users 230 days 100 screens per day 10 sec per screen savings 1278 hours or 32 weeks 2001 Marilyn Mantei and John Mylopoulos Interface Design 3 Information Systems Analysis and Design csc340 Reduced Training Costs 20 employees X 2 systems applications per year X 2 1 2 days per application saved 100 days or 20 weeks of savings Training and support often more costly than hardware and software 2001 Marilyn Mantei and John Mylopoulos Interface Design 4 Information Systems Analysis and Design csc340 Preventable User Errors 500 users X 20 errors per year X 15 minutes per error 2500 hours lost or 63 weeks 2001 Marilyn Mantei and John Mylopoulos Information Systems Analysis and Design Interface Design 5 csc340 Increased Productivity 500 menu selections per day X 2 sec per selection saved X 230 days per year 320 hours or 8 weeks For a 100K person year cost saved time translates to 15 000 2001 Marilyn Mantei and John Mylopoulos Interface Design 6 Information Systems Analysis and Design csc340 Serious Life Threatening Errors n Analysis of transcript of 911 call announcing bomb in Centennial Park at the Atlanta Olympics indicated that 20 minutes were needed to call dispatchers Dispatch system required an address for Centennial Park Dispatch operators could not find anyone who knew address Bomb was set to go off 30 minutes after call n Airline crashed into a mountainside in Colombia in 1996 killing all aboard including a well known computer scientist and his whole family Pilot typed in R rather than full name of airport Guidance system took first airport in the list beginning with R which was the wrong airport Plane ran into mountain 2001 Marilyn Mantei and John Mylopoulos Interface Design 7 Information Systems Analysis and Design csc340 User Interface Economics n Good user interfaces sell systems Windows is a copy of the Macintosh interface The Mac interface is a copy of Bravo developed by user interface researchers at Xerox PARC n User interface capabilities and awareness help get contracts n Poor user interfaces can cripple a system that is outstanding in all other respects n Computer driven interfaces placed in most mechanical products we know Classic problem of users not being able to set the clock on their VCR Users often can t use a photocopy machine a fax machine a cash register a candy machine a bank machine or even a telephone Cars will eventually be completely computer driven 2001 Marilyn Mantei and John Mylopoulos Interface Design 8 Information Systems Analysis and Design csc340 Why Are User Interfaces Poor n n n n n Inadequate training of people developing interfaces Diversity of knowledge required to design good interfaces Rapid technological advances Reluctance of companies to commit resources Poor management programmers do not talk to user design teams and vice versa n User Interface specialists rarely involved n The bricklayers programmers are left to design the user interface by default Ignorance by software engineers of usability and how to measure it is roughly equivalent to an electronics engineer not knowing what volts and watts are and how to measure them 2001 Marilyn Mantei and John Mylopoulos Interface Design 9 Information Systems Analysis and Design csc340 What s Wrong with this Interface Design Design of User Interface for CAVECAT Media Space 2001 Marilyn Mantei and John Mylopoulos Interface Design 10 Information Systems Analysis and Design csc340 Why is this Design Better Design of User Interface for Telepresence Media Space 2001 Marilyn Mantei and John Mylopoulos Interface Design 11 Information Systems Analysis and Design csc340 Some Basic Human Characteristics n n n n n n Humans like to problem solve but don t like unsolvable problems Humans are always learning but learning is hard Humans use prior learning to support new learning Users don t read manuals but work by copying and asking Users are always building models of their world Implications Build interfaces that allow people to learn by using the interface Build interfaces that suggest correct models Build interfaces that rely on prior learning n Users don t mind if something doesn t make sense they build their own model to make it make sense n Users prefer simple models n Inconsistency doesn t bother users A simple model which doesn t always match is better than a complex model that is too hard to learn 2001 Marilyn Mantei and John Mylopoulos Interface Design 12 Information Systems Analysis and Design csc340 Characteristics of a Well Designed Interface The design of the user interface n Has affordances makes each operation visible n Offers obvious mappings makes the relationship between the actual action of the device and the action of the user obvious n Provides feedback on the user s action n Provides a good mental model of the underlying behaviour of the device n Provides forcing functions prevents a user from making bad errors n Supports automatic learning provides consistencies and practice that help the user acquire interface skills 2001 Marilyn Mantei and John Mylopoulos Interface Design 13 Information Systems Analysis and Design csc340 Affordances n Affordance of an artifact means that the design of the artifact in some way describes what the user can do with it i e indicates what operation the user may perform n
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