User-Centered Interface Design andDevelopment-- Chapter 1: Introduction --Franz KurfessWinter 20050.5Copyright © 2005 Franz J. Kurfess• good vs. bad design• interaction design• interaction design process• goals of interaction design• design and usability principlesChapter OverviewCopyright © 2005 Franz J. Kurfess 2 / 26Interaction Design?Interaction Design?Copyright © 2005 Franz J. Kurfess 3 / 26• interactive products• interactive systems• design emphasis on the system• design emphasis on the userScope and EmphasisInteraction Design? Copyright © 2005 Franz J. Kurfess 4 / 26• intended for a relatively narrow taks• functionality exposed to the user is relatively lowExamples• TV• phone• coffee maker• door• computer mouseInteractive ProductsInteraction Design? Copyright © 2005 Franz J. Kurfess 5 / 26• intended for a a wide range of taks• user has to deal with complex functionality• computer• car• entertainment system (stereo)• espresso machineInteractive SystemsInteraction Design? Copyright © 2005 Franz J. Kurfess 6 / 26Good vs. Bad DesignGood vs. Bad DesignCopyright © 2005 Franz J. Kurfess 7 / 26• emphasis is on user experience• tensions between various factors••What's the Difference?Good vs. Bad Design Copyright © 2005 Franz J. Kurfess 8 / 26• product performs its task• satisfactory, enjoyable user experience• functionality and performance are critical (withinlimits)• the outcome of the task should match or exceedthe user's expectations• performing the task and using the product shouldbe easy• unexpected events should distract as little as pos-sible• users with different capabilities should be accom-modatedGood Design Makes Users HappyGood vs. Bad Design Copyright © 2005 Franz J. Kurfess 9 / 26Scenario: Assume your grandmother is going on along roadtrip involving a long stretch of road in anunpopulated area. From a usability perspective, is itbetter for her to have a cell phone with her, or wouldyou rather explain to her how the road-side emer-gency phones work?• aspects to consider• functionality: what are the most importanttasks• performance: how good are the products atthose tasks• capabilities and background of the user• environment: external factors that influencethe user experienceProduct Analysis ActivityGood vs. Bad Design Copyright © 2005 Franz J. Kurfess 10 / 26Product Analysis Activity (Continued)Good vs. Bad Design Copyright © 2005 Franz J. Kurfess 11 / 26or worse ...• lack of functionality or poor performance• difficulty in obtaining a desired result• actions achieve unexpected results• product is difficult to handle• appearence of the product is unpleasantPoor Design Makes Users UnhappyGood vs. Bad Design Copyright © 2005 Franz J. Kurfess 12 / 26• critcal aspects of many products• designers are often aware of them• often conscious decisions to sacrifice them be-cause of other important aspects (cost, safety,manufacturing)• these aspects are in the focus of designes and en-gineers• sometimes designers are not aware of the import-ance users place on certain functionality and per-formance criteria• the product may be used for unexpected tasks orin unintended ways• the product is targeted at the wrong user group•Functionality and PerformanceGood vs. Bad Design Copyright © 2005 Franz J. Kurfess 13 / 26• using a product for its intended task is not alwaysobvious for most users• task familiarity• user background• environment• since the designer spent a lot of time working onthe product, it is obvious to them how to use it• especially difficult for tasks the user is not veryfamiliar with• user limitations (focus, ergonomics)• (perceived) urgency or danger can cause stress• aspects of the environment (e.g. movement,noise) can add to difficultiesAchieving ResultsGood vs. Bad Design Copyright © 2005 Franz J. Kurfess 14 / 26• an interaction with the product does not producethe expected result•• beyond the parameters the user considers for per-formance and functionality• may lead to confusion or worse consequences• inconsistent outcomes are especially bad• "you should have read the manual" is not enough• if possible, products should be designed to pre-vent bad outcomes in addition to enabling goodonesUnexpected OutcomesGood vs. Bad Design Copyright © 2005 Franz J. Kurfess 15 / 26• manipulation of interaction mechanisms• makes use of the "affordances" of a product• touching and experiencing physical aspects ofthe product while it is being used• affordances are the "natural" or "obvious" inter-action mechanisms with a product• physical interactions with the product have a sig-nificant impact on user experience• users may have difficulties explaining why theylike or dislike the way a product "feels"• ergonomics deals with such issues• can be especially challenging for engineers••Product HandlingGood vs. Bad Design Copyright © 2005 Franz J. Kurfess 16 / 26• sensory percepts relayed by the product• most often looks, sometimes sound, touch, smell• appearance may not be relevant for functionalityor performance• it can be an important criterion for users to distin-guish "good" from "poor" design• sometimes design is used as a synonym for ap-pearance (not in this class)• can also be a major challenge for engineers• may depend on fashion ("fad")AppearanceGood vs. Bad Design Copyright © 2005 Franz J. Kurfess 17 / 26What is Interaction Design?What is Interaction Design?Copyright © 2005 Franz J. Kurfess 18 / 26“Designing interactive products to support people intheir everyday and working lives [Preece, Rogers,and Sharp, 2002].”• emphasis on support of people, not on highestfunctionality or performance• includes professional and personal activitiesDefinition of Interaction DesignWhat is Interaction Design? Copyright © 2005 Franz J. Kurfess 19 / 26• before computers were widely used, most com-plex systems were designed by engineers for en-gineers• now, many devices perform complex tasks forregular users• often it is unrealistic to expect users to spend alot of energy on learning how to use products• functionality and performance used to be moreimportant as distinguishing factors, but that ischanging for more and more products• our professional and personal lives are becominginundated with products that perform complextasks• some of these products may affect critical as-pects like health,