Bài giảng Systems Analysis and Design - Chapter 14: Human Computer Interface

Human Computer InterfaceSystems Analysis and Design, 7eKendall & Kendall14© 2008 Pearson Prentice HallKendall & Kendall14-*Learning ObjectivesUnderstand human-computer interactionKnow how fit affects performance and well-beingUnderstand the technology acceptance model (TAM) and usabilityKnow how to design for individuals and persons with disabilitiesUnderstand the different types of, and reasons for, using alternative user interfacesKendall & Kendall14-*Learning Objectives (Continued)Design effective dialog for HCIUnderstand the importance of user feedbackArticulate HCI implications for designing ecommerce Web sitesFormulate queries that permit users to search the WebKendall & Kendall14-*Human-Computer InteractionAwareness of HCIAttentiveness to issues of HCIExistence of HCI in organizational settingsNeed to master the concepts surrounding HCIGuidelines for usabilityKendall & Kendall14-*Major TopicsUnderstanding human-computer interactionFitTAMDesigning for cognitive styles of individual usersPhysical considerations in HCI designUser interfacesDialog designFeedbackQueriesKendall & Kendall14-*Understanding Human-Computer InteractionKnowledge about the interplay among users, tasks, task contexts, IT, and the environments in which the systems are used comprises the basis of human-computer interactionKendall & Kendall14-*FitThe “fit” between the HCI elements of the human, the computer, and the task that needs to be performed leads to performance and well-beingKendall & Kendall14-*Figure 14.1 The “fit” among the human, computer, and task affects performance and well-beingKendall & Kendall14-*TaskComplex tasks that require human, system, and task interaction are supported by ecommerce and Web systems, ERP systems, and wireless systems inside and outside of the organizationCan be structured and routine or ill-defined and without apparent structureKendall & Kendall14-*PerformanceA combination of the efficiency involved in performing a task and the quality of the work that is produced by the taskKendall & Kendall14-*Well-BeingConcern for a human’s overall comfort, safety, and healthPsychological attitudes are also importantKendall & Kendall14-*The Technology Acceptance Model (TAM) and AttitudeA way for analysts to organize their thinking about whether users will accept and use information technologyCan be used to shape training after a system has been developedCan be used to garner user reactions to prototypesExamines perceived usefulness and perceived ease of useKendall & Kendall14-*The Technology Acceptance Model (TAM) and Attitude (Continued)AttitudesSatisfactionAnxietyEnjoymentPlayfulnessKendall & Kendall14-*UsabilityA way for designers to evaluate the systems and interfaces they create with an eye toward addressing as many HCI concerns as thoroughly possibleUsability standardsUsability heuristicsKendall & Kendall14-*Designing for Cognitive Styles of Individual UsersMaking sure data is made available in different forms TablesGraphsTextDifferent timesKendall & Kendall14-*Pivot TablesAllows a user to arrange data in a table in any way they chooseGives users greater control over how they look at data in different ways within a tableKendall & Kendall14-*Figure 14.3 A pivot table template can make it easier for users to see information displayed in different waysKendall & Kendall14-*Visual Analysis of DatabasesSupport visual thinkingExtend the user’s cognitive capabilitiesIncrease the changes of making an appropriate decisionKendall & Kendall14-*Figure 14.7 When different graphs or tables can be displayed on the same page, the page resembles a dashboard. (Courtesy of www.tableausoftware.com.)Kendall & Kendall14-*Physical Considerations in HCI DesignVisionHearingTouchKendall & Kendall14-*Considering Human Limitations, Disabilities, and DesignAn individual with a disability is a person who:Has a physical or mental impairment that substantially limits one or more major life activitiesHas a record of such impairment, orIs regarded as having such an impairmentKendall & Kendall14-*Figure 14.8 The HCI approach to systems design emphasizes the fit among the human, computer, and taskKendall & Kendall14-*Interface Design Objectives Match the user interface to the taskMake the user interface efficientProvide appropriate feedback to usersGenerate usable queriesImprove productivity of computer usersKendall & Kendall14-*Types of User InterfacesNatural-language interfacesQuestion-and-answer interfacesMenus Form-fill interfacesCommand-language interfacesGraphical User Interfaces (GUIs)Web interfacesKendall & Kendall14-*Natural-Language InterfacesPermit users to interact with the computer in their everyday or "natural" languageImplementation problems and extraordinary demand on computing resources have so far kept natural-language interfaces to a minimumKendall & Kendall14-*Question-and-Answer InterfacesThe computer displays a question to the user on the displayThe user enters an answer The computer acts on that input information in a preprogrammed mannerUsers unfamiliar with applications may find question-and-answer interfaces most comfortableKendall & Kendall14-*Menus Provides the user with an onscreen list of available selectionsNot hardware dependentCan be put aside until the user wants to use themCan be nested within one another to lead a user through options in a programGUI menusObject menuKendall & Kendall14-*Form-Fill Interfaces (Input/Output Forms)Onscreen forms or Web-based forms displaying fields containing data items or parameters that need to be communicated to the userAdvantageThe filled-in form provides excellent documentationDisadvantageUsers experienced with the system or application may become impatientKendall & Kendall14-*Figure 14.12 An example of the form-fill interface from Form Flow by JetformKendall & Kendall14-*Command-Language InterfacesAllows the user to control the application with a series of keystrokes, commands, phrases, or some sequence of theseAffords the user more flexibility and controlRequire memorization of syntax rulesMay be an obstacle for inexperienced usersKendall & Kendall14-*Figure 14.13 Command-language interfaceKendall & Kendall14-*Graphical User InterfacesProvide users constant feedback on task accomplishmentAn appropriate model of reality or an acceptable conceptual model of the representation must be inventedKendall & Kendall14-*Other User InterfacesPointing devicesTouch-sensitive screensSpeech recognition and synthesisKendall & Kendall14-*Speech Recognition and SynthesisThe user speaks to the computer, and the system is able to recognize an individual’s vocal signals, convert them, and store the inputContinuous speech systemsSpeaker independenceKendall & Kendall14-*Figure 14.14 Using software such as Dragon NaturallySpeaking by Nuance, a user can speak commands to their computer. In this example, the user corrects a word by pulling up a menu of alternative words that sound the sameKendall & Kendall14-*Evaluating InterfacesTraining period for users should be acceptably shortUsers early in their training should be able to enter commands without thinking about them, or referring to a help menu or manualThe interface should be seamless so that errors are few, and those that do occur are not occurring because of poor designTime that users and the system need to bounce back from errors should be shortInfrequent users should be able to relearn the system quicklyKendall & Kendall14-*Guidelines for Dialog DesignMeaningful communicationMinimal user actionStandard operation and consistencyKendall & Kendall14-*Meaningful CommunicationThe system should present information clearly to the userUsers with less skill with a computer require more communicationEasy to use help screens Kendall & Kendall14-*Minimal User ActionKeying codes instead of whole wordsEntering data that are not already stored on filesSupplying the editing charactersUsing default values for fields on entry screensDesigning an inquiry, change, or delete program so that the user needs to enter only the first few characters of a name or item descriptionKendall & Kendall14-*Minimal User Action (Continued)Providing keystrokes for selecting pull-down menu optionsUse radio buttons and drop-down lists to control displays of new Web pages or to change Web formsProvide cursor control for Web forms and other displays so the cursor moves to the next field when the right number of characters has been enteredKendall & Kendall14-*Standard Operation and ConsistencyLocating titles, date, time, and operator and feedback messages in the same places on all displaysExiting each program by the same key or menu optionCanceling a transaction in a consistent wayObtaining help in a standardized wayStandardizing the colors used for all displays or Web pagesKendall & Kendall14-*Standard Operation and Consistency (Continued)Standardizing the use of icons for similar operations when using graphical user interfaceUsing consistent terminology in a display or Web siteProviding a consistent way to navigate through the dialogUsing consistent font alignment, size, and color on a Web pageKendall & Kendall14-*Figure 14.16 This tab control dialog box has seven tabs. The chosen tab “Paper” appears as if it is in front of the other tabsKendall & Kendall14-*Feedback for UsersAll systems require feedback to monitor and change behaviorFeedback compares current behavior with predetermined goals and gives back information describing the gap between actual and intended performanceKendall & Kendall14-*Types of FeedbackAcknowledging acceptance of inputRecognizing that input is in the correct formNotifying that input is not in the correct formExplaining a delay in processingAcknowledging that a request is completedNotifying that a request was not completedOffering the user more detailed feedback Kendall & Kendall14-*Including Feedback in DesignCan be a powerful reinforcer of users’ learning processesServe to improve user performance with the systemIncrease their motivation to produceImprove the fit among the user, task and the technologyKendall & Kendall14-*A Variety of Help OptionsPressing a function key, such as F1A GUI pull-down menuContext-sensitive helpIcon tipsWizardsOnline help or help linesSoftware forumsKendall & Kendall14-*Special Design Considerations for EcommerceSoliciting feedback from ecommerce Web site customersEasy navigation for ecommerce Web sitesCan readily return to the Web siteKendall & Kendall14-*Soliciting Feedback from Ecommerce Web Site CustomersLaunch the user’s email programTake users to a blank message template when they click on “feedback”Kendall & Kendall14-*Easy Navigation for Ecommerce Web Sites (One-Click Navigation)Creating a rollover menuBuilding a collection of hierarchical linksPlacing a site map on the home page and emphasizing the link to itPlacing a navigational bar on every inside page that repeats the categories used on the entry screenKendall & Kendall14-*Easy Navigation for Ecommerce Web Sites (Other Considerations)Search functionCreating flexibilityCreating for users with different cognitive processing , or interestsKeeping the customers on the Web siteKendall & Kendall14-*Designing QueriesHelp reduce users’ time spend in querying the databaseHelp them find the data they wantResult in a smoother user experience overallKendall & Kendall14-*Query TypesQuery Type 1 What is the value of a specified attribute for a particular entityQuery Type 2What entity has a specified value for a particular attributeQuery Type 3What attribute(s) has (have) a specified value for a particular entityKendall & Kendall14-*Query Types (Continued)Query Type 4List all the values for all the attributes for a particular entityQuery Type 5List all entities that have a specified value for all attributesQuery Type 6List all the attributes that have a specified value for all entitiesKendall & Kendall14-*Figure 14.21 It is possible to perform six basic types of queries on a table that contains entities, attributes, and valuesKendall & Kendall14-*Query Notation V is value, E is entity, A is attributes, variables in parentheses are given:Query type 1: V  (E, A)Query type 2: E  (V, A)Query type 3: A  (V, E)Query type 4: all V  (E, all A)Query type 5: all E  (V, all A)Query type 6: all A  (V, all E)Kendall & Kendall14-*Building More Complex QueriesArithmetic operations are performed firstExponentiationEither multiplication or divisionAddition or subtractionComparative operations are performedGT, LT , and othersBoolean operations are performedFirst AND and then ORKendall & Kendall14-*Query MethodsQuery By Example (QBE), the database fields are selected and displayed in a grid, and requested query values are either entered in the field area or below the fieldStructured Query Language (SQL), uses a series of words and commands to select the rows and columns that should be displayed in the resulting tableKendall & Kendall14-*Figure 14.23 Query by example using Microsoft accessKendall & Kendall14-*Figure 14.26 Structured Query Language (SQL) for the CUSTOMER NAME parameter queryKendall & Kendall14-*Summary Human-computer interaction (HCI)User interfacesTAMUsabilityHCI approachKendall & Kendall14-*Summary (Continued)Designing the user interfaceNatural languageQuestion and answerMenusForm-fill and Web-based form-fillGraphical user interfacesThe mouseLightpensThe stylusTouch-sensitive screensVoice recognition systemsKendall & Kendall14-*Summary (Continued)Designing user feedbackLet users know if their input is being acceptedIf input is or is not in the correct formIf processing is going onIf requests can or cannot be processedIf more detailed information is available and how to get itKendall & Kendall14-*Summary (Continued)Designing ecommerce Web site feedbackRollover menusHierarchical displays of links Site mapsNavigation barsQueriesSix basic types