Strategies for Effective
`
`Corel Exhibit 2009
`Microsoft v. Corel
`IPR2016-01083
`
`

`
`Designing the User Interlace
`
`Strategies for Effective
`Human-Computer Interaction
`Third Edition
`
`Ben Shneiderman
`The University of Maryland
`
`A ADDISON-WESLEY
`NYV
`An imprint of Addison Wesley Longman, Inc.
`
`Reading, Massachusetts • Harlow, England • Menlo Park, California
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`Many of the designations used by manufacturers and sellers to distinguish their
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`book, and Addison-Wesley was aware of a trademark claim, the designations
`have been printed in initial caps or all caps.
`
`Library of Congress Cataloging-in-Publication Data
`Shneiderman, Ben.
`Designing the user interface : strategies for effective human
`-computer-interaction / Ben Shneiderman. 3rd ed.
`p. cm.
`Includes bibliographical references and index.
`ISBN 0-201-69497-2
`1. Human-computer interaction. 2. User interfaces (Computer
`systems) (cid:9)
`I. Title.
`QA76.9.H85S54 1998
`004.01'9--dc21 (cid:9)
`
`96-37974
`CIP
`
`Access the latest information about Addison-Wesley titles from our World Wide
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`
`Chapter opener illustrations from art provided by Mark Kostabi. Reproduced
`with permission.
`
`Cover art @ Boris Lyubner/SIS
`
`Copyright @ 1998 by Addison Wesley Longman, Inc.
`
`All rights reserved. No part of this publication may be reproduced, stored in a
`retrieval system, or transmitted, in any form or by any means, electronic,
`mechanical, photocopying, recording, or otherwise, without the prior written
`permission of the publisher. Printed in the United States of America.
`
`1 2345 6 78 9 10-MA-0100999897
`
`

`
`2.4 Principle 1: Recognize the Diversity (cid:9)
`
`71
`
`FREQUENCY OF TASK BY JOB TITLE
`
`Query by
`Patient
`
`Update
`Data
`
`0.14
`0.06
`0.01
`
`0.26
`
`0.07
`
`0.11
`0.04
`0.01
`
`0.04
`
`Task
`
`Query
`across
`Patients
`
`0.04
`
`0.04
`0.08
`0.02
`
`Add
`Relations
`
`Evaluate
`System
`
`0.01
`
`0.02
`
`0.05
`
`Job title
`
`Nurse
`Physician
`Supervisor
`Appointment
`personnel
`Medical-record
`maintainer
`Clinical researcher
`Database programmer
`
`Figure 2.3
`
`Hypothetical frequency-of-use data for a medical clinic information system.
`Answering queries from appointments personnel about individual patients is the
`highest-frequency task.
`
`out this task. A more precise analysis would include frequencies instead of
`just simple check marks.
`
`2.4.3 Interaction styles
`
`When the task analysis is complete and the task objects and actions have
`been identified, the designer can choose from these primary interaction
`styles: menu selection, form fillin, command language, natural language,
`and direct manipulation (Box 2.1). Chapters 6 through 8 explore these styles
`in detail; here, we give a comparative overview to set the stage.
`
`Direct manipulation When a clever designer can create a visual representa-
`tion of the world of action, the users' tasks can be greatly simplified because
`direct manipulation of familiar objects is possible. Examples of such systems
`include the popular desktop metaphor, computer-assisted—design tools, air-
`traffic—control systems, and video games. By pointing at visual representa-
`tions of objects and actions, users can carry out tasks rapidly and can observe
`the results immediately. Keyboard entry of commands or menu choices is
`
`

`
`72 (cid:9)
`
`2 Theories, Principles, and Guidelines
`
`Box 2.1
`
`Advantages and disadvantages of the five primary interaction styles.
`
`Advantages
`Direct manipulation
`visually presents task concepts
`allows easy learning
`
`Disadvantages
`
`may be hard to program
`may require graphics display and
`pointing devices
`
`allows easy retention
`allows errors to be avoided
`encourages exploration
`affords high subjective satisfaction
`Menu selection
`shortens learning (cid:9)
`reduces keystrokes (cid:9)
`structures decision making (cid:9)
`permits use of dialog-management (cid:9)
`tools
`allows easy support of error handling
`Form fillin
`simplifies data entry (cid:9)
`requires modest training
`gives convenient assistance
`permits use of form-management tools
`Command language
`is flexible (cid:9)
`appeals to "power" users (cid:9)
`
`supports user initiative
`allows convenient creation of user-
`defined macros
`Natural language
`relieves burden of learning syntax
`
`presents danger of many menus
`may slow frequent users
`consumes screen space
`requires rapid display rate
`
`consumes screen space
`
`has poor error handling
`requires substantial training and
`memorization
`
`requires clarification dialog
`may require more keystrokes
`may not show context
`is unpredictable
`
`

`
`2.4 Principle 1: Recognize the Diversity (cid:9)
`
`73
`
`replaced by use of cursor-motion devices to select from a visible set of objects
`and actions. Direct manipulation is appealing to novices, is easy to remem-
`ber for intermittent users, and, with careful design, it can be rapid for fre-
`quent users. Chapter 6 describes direct manipulation and its application.
`
`Menu selection In menu-selection systems, users read a list of items, select
`the one most appropriate to their task, and observe the effect. If the terminol-
`ogy and meaning of the items are understandable and distinct, then users can
`accomplish their tasks with little learning or memorization and just a few
`actions. The greatest benefit may be that there is a clear structure to decision
`making, since all possible choices are presented at one time. This interaction
`style is appropriate for novice and intermittent users and can be appealing to
`frequent users if the display and selection mechanisms are rapid.
`For designers, menu-selection systems require careful task analysis to
`ensure that all functions are supported conveniently and that terminology
`is chosen carefully and used consistently. Advanced user interface build-
`ing tools to support menu selection are an enormous benefit in ensuring
`consistent screen design, validating completeness, and supporting main-
`tenance.
`
`Form fillin When data entry is required, menu selection usually becomes
`cumbersome, and form fillin (also called fill in the blanks) is appropriate.
`Users see a display of related fields, move a cursor among the fields, and
`enter data where desired. With the form-fillin interaction style, users must
`understand the field labels, know the permissible values and the data-entry
`method, and be capable of responding to error messages. Since knowledge of
`the keyboard, labels, and permissible fields is required, some training may
`be necessary. This interaction style is most appropriate for knowledgeable
`intermittent users or frequent users. Chapter 7 provides a thorough treat-
`ment of menus and form fillin.
`
`Command language For frequent users, command languages provide a
`strong feeling of locus of control and initiative. Users learn the syntax and
`can often express complex possibilities rapidly, without having to read dis-
`tracting prompts. However, error rates are typically high, training is neces-
`sary, and retention may be poor. Error messages and online assistance are
`hard to provide because of the diversity of possibilities plus the complexity
`of mapping from tasks to interface concepts and syntax. Command lan-
`guages and lengthier query or programming languages are the domain of
`expert frequent users, who often derive great satisfaction from mastering a
`complex set of semantics and syntax.
`
`Natural language The hope that computers will respond properly to arbitrary
`natural-language sentences or phrases engages many researchers and system
`
`

`
`74 (cid:9)
`
`2 Theories, Principles, and Guidelines
`
`developers, in spite of limited success thus far. Natural-language interaction
`usually provides little context for issuing the next command, frequently
`requires clarification dialog, and may be slower and more cumbersome than the
`alternatives. Still, where users are knowledgeable about a task domain whose
`scope is limited and where intermittent use inhibits command-language train-
`ing, there exist opportunities for natural-language interfaces (discussed at the
`end of Chapter 8).
`Blending several interaction styles may be appropriate when the required
`tasks and users are diverse. Commands can lead the user to a form fillin where
`data entry is required, or menus can be used to control a direct-manipulation
`environment when a suitable visualization of actions cannot be found.
`
`2.5 Principle 2: Use the Eight Golden Rules of
`Interface Design
`
`Later chapters cover constructive guidance for design of direct manipula-
`tion, menu selection, command languages, and so on. This section presents
`underlying principles of design that are applicable in most interactive sys-
`tems. These underlying principles of interface design, derived heuristically
`from experience, should be validated and refined.
`
`1. Strive for consistency. This rule is the most frequently violated one, but fol-
`lowing it can be tricky because there are many forms of consistency. Consis-
`tent sequences of actions should be required in similar situations; identical
`terminology should be used in prompts, menus, and help screens; and con-
`sistent color, layout, capitalization, fonts, and so on should be employed
`throughout. Exceptions, such as no echoing of passwords or confirmation of
`the delete command, should be comprehensible and limited in number.
`2. Enable frequent users to use shortcuts. As the frequency of use increases, so
`do the user's desires to reduce the number of interactions and to increase
`the pace of interaction. Abbreviations, special keys, hidden commands,
`and macro facilities are appreciated by frequent knowledgeable users.
`Short response times and fast display rates are other attractions for fre-
`quent users.
`3. Offer informative feedback. For every user action, there should be system
`feedback. For frequent and minor actions, the response can be modest,
`whereas for infrequent and major actions, the response should be more
`substantial. Visual presentation of the objects of interest provides a con-
`
`

`
`2.5 Principle 2: Use the Eight Golden Rules of Interface Design (cid:9)
`
`75
`
`venient environment for showing changes explicitly (see discussion of
`direct manipulation in Chapter 6).
`4. Design dialogs to yield closure. Sequences of actions should be organized
`into groups with a beginning, middle, and end. The informative feedback
`at the completion of a group of actions gives operators the satisfaction of
`accomplishment, a sense of relief, the signal to drop contingency plans
`and options from their minds, and an indication that the way is clear to
`prepare for the next group of actions.
`5. Offer error prevention and simple error handling. As much as possible, design
`the system such that users cannot make a serious error; for example, prefer
`menu selection to form fain and do not allow alphabetic characters in
`numeric entry fields. If users make an error, the system should detect the
`error and offer simple, constructive, and specific instructions for recovery.
`For example, users should not have to retype an entire command, but
`rather should need to repair only the faulty part. Erroneous actions should
`leave the system state unchanged, or the system should give instructions
`about restoring the state.
`6. Permit easy reversal of actions. As much as possible, actions should be
`reversible. This feature relieves anxiety, since the user knows that errors
`can be undone, thus encouraging exploration of unfamiliar options. The
`units of reversibility may be a single action, a data-entry task, or a com-
`plete group of actions such as entry of a name and address block.
`7. Support internal locus of control. Experienced operators strongly desire the
`sense that they are in charge of the system and that the system responds to
`their actions. Surprising system actions, tedious sequences of data entries,
`inability or difficulty in obtaining necessary information, and inability to
`produce the action desired all build anxiety and dissatisfaction. Gaines
`(1981) captured part of this principle with his rule avoid acausality and his
`encouragement to make users the initiators of actions rather than the respon-
`ders to actions.
`8. Reduce short-term memory load. The limitation of human information pro-
`cessing in short-term memory (the rule of thumb is that humans can
`remember "seven-plus or minus-two chunks" of information) requires
`that displays be kept simple, multiple page displays be consolidated,
`window-motion frequency be reduced, and sufficient training time be
`allotted for codes, mnemonics, and sequences of actions. Where appro-
`priate, online access to command-syntax forms, abbreviations, codes, and
`other information should be provided.
`
`These underlying principles must be interpreted, refined, and extended
`for each environment. The principles presented in the ensuing sections
`
`

`
`76 (cid:9)
`
`2 Theories, Principles, and Guidelines
`
`focus on increasing the productivity of users by providing simplified data-
`entry procedures, comprehensible displays, and rapid informative feed-
`back that increase feelings of competence, mastery, and control over the
`system.
`
`2.6 Principle 3: Prevent Errors
`
`There is no medicine against death, and against error no rule has been found.
`
`Sigmund Freud (Inscription he wrote on his portrait)
`
`Users of word processors, spreadsheets, database-query facilities, air-traf-
`fic–control systems, and other interactive systems make mistakes far more
`frequently than might be expected. Card et al. (1980) reported that experi-
`enced professional users of text editors and operating systems made mis-
`takes or used inefficient strategies in 31 percent of the tasks assigned to
`them. Brown and Gould (1987) found that even experienced authors made
`errors in almost half their spreadsheets. Other studies reveal the magnitude
`of the problem of—and the loss of productivity due to—user errors.
`One way to reduce the loss in productivity due to errors is to improve the
`error messages provided by the computer system. Shneiderman (1982)
`reported on five experiments in which changes to error messages led to
`improved success at repairing the errors, lower error rates, and increased sub-
`jective satisfaction. Superior error messages were more specific, positive in
`tone, and constructive (telling the user what to do, rather than merely report-
`ing the problem). Rather than using vague and hostile messages, such as
`SYNTAX ERROR or ILLEGAL DATA, designers were encouraged to use infor-
`mative messages, such as UNMATCHED LEFT PARENTHESIS or
`MENU CHOICES ARE IN THE RANGE OF 1 TO 6.
`Improved error messages, however, are only helpful medicine. A more
`effective approach is to prevent the errors from occurring. This goal is more
`attainable than it may seem in many systems.
`The first step is to understand the nature of errors. One perspective is that
`people make mistakes or "slips" (Norman, 1983) that designers help them to
`avoid by organizing screens and menus functionally, designing commands
`or menu choices to be distinctive, and making it difficult for users to take
`irreversible actions. Norman offers other guidelines, such as do not have
`modes, do offer feedback about the state of the system, and do design for
`consistency of commands. Norman's analysis provides practical examples
`and a useful theory.
`
`

`
`268 (cid:9)
`
`7 Menu Selection, Form Fillin, and Dialog Boxes
`
`pointing devices, use of color, handling of special cases, and integration of a
`word processor to allow remarks.
`
`7.8 Dialog Boxes
`
`In modern GUIs, users can make some choices from pull-down or pop-up
`menus, but many tasks require multiple selections as well as data entry of
`numeric values or alphanumeric strings. The most common solution to com-
`plex tasks is to provide a dialog box for users. Familiar examples include the
`Open, Save, Find, Replace, and Spell Check dialog boxes (Fig. 7.10). Dialog
`boxes can also contain task-specific functions, such as entering customer
`name and address for a car rental; specifying clothing color, size, and fabric
`for an order-entry system; or selecting colors and textures for a geographic-
`information system.
`Dialog-box design combines menu-selection and form-fillin issues with
`additional concerns about consistency across hundreds of dialog boxes and
`relationship with other items on the screen (Galitz, 1994). A guidelines docu-
`ment for dialog boxes can help to ensure appropriate consistency (Box 7.3).
`Dialog boxes should have meaningful titles to identify them, and should have
`consistent visual properties—for example, centered, mixed uppercase and
`lowercase, 12-point, black, Helvetica font. Dialog boxes are often shaped and
`sized to fit each situation, but distinctive sizes or aspect ratios may be used to
`signal errors, confirmations, or components of the application. Within a dia-
`
`Select a Document:
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`
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`
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`go
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`Open
`
`(Cancel
`
`(Desktop)
`
`Find File...
`LI Read Only
`
`Figure 7.10
`
`Open dialog box from Microsoft Word for the Macintosh.
`
`

`
`7.8 Dialog Boxes (cid:9)
`
`269
`
`Box 7.3
`
`Dialog Box Guidelines
`
`Internal layout: like that of menus and forms
`
`• Meaningful title, consistent style
`• Top-left to bottom-right sequencing
`• Clustering and emphasis
`• Consistent layouts (margins, grid, whitespace, lines, boxes)
`• Consistent terminology, fonts, capitalization, justification
`• Standard buttons (OK, Cancel)
`• Error prevention by direct manipulation
`
`External relationship
`
`• Smooth appearance and disappearance
`• Distinguishable but small boundary
`• Size small enough to reduce overlap problems
`• Display close to appropriate items
`• No overlap of required items
`• Easy to make disappear
`• Clear how to complete/cancel
`
`log box, there should be standard margins and visual organization, typically
`from top-left to bottom-right for languages that read left to right. A grid struc-
`ture helps to organize the contents, and symmetry can be used to provide
`order when appropriate. Clustering of related items within a box or separa-
`tion by horizontal and vertical rules gives users help in understanding the
`contents. Emphasis can be added by color, font size, or style of type.
`The elements of a dialog box will depend on the toolkit or design tool (see
`Chapter 5), but they usually include buttons, check boxes, fill in fields, list
`boxes, combo boxes, and sliders. Standard buttons—with consistent labels,
`colors, and fonts—help users to navigate correctly and quickly. Where possi-
`ble, users should be able to undo each step, and should be prevented from
`making errors.
`Dialog-box design also involves the relationship with the current contents
`of the screen. Since dialog boxes usually pop up on top of some portion of the
`screen, there is a danger that they will obscure relevant information. There-
`fore, dialog boxes should be as small as is reasonable to minimize the overlap
`
`

`
`270 (cid:9)
`
`7 Menu Selection, Form Fillin, and Dialog Boxes
`
`and visual disruption. Dialog boxes should appear near, but not on top of, the
`related screen items. When a user clicks on a city on a map, the dialog box
`about the city should appear just next to the click point. The most common
`annoyance is to have the Find or Spell Check box obscure a relevant part of
`the text.
`Dialog boxes should be distinct enough that users can easily distinguish
`them from the background, but should not be so harsh as to be visually dis-
`ruptive. Finally, dialog boxes should disappear easily with as little visual dis-
`ruption as possible (see Section 13.4 and 13.5).
`When tasks are complex, multiple dialog boxes may be needed, leading
`some designers to chose a tabbed dialog box, in which two to 20 protruding
`tabs indicate the presence of multiple dialog boxes. This technique can be
`effective, but carries with it the potential problem of too much fragmentation;
`users may have a hard time finding what they want underneath the tabs. A
`smaller number of larger dialog boxes may be advantageous, since users usu-
`ally prefer doing visual search to having to remember where to find a desired
`control.
`
`7.9 Practitioner's Summary
`
`Concentrate on organizing the structure and sequence of menus to match the
`users' tasks, ensure that each menu is a meaningful task-related unit, and cre-
`ate items that are distinctive and comprehensible. If some users make fre-
`quent use of the system, then typeahead, shortcut, or macro strategies should
`be allowed. Permit simple traversals to the previously displayed menu and
`to the main menu. Be sure to conduct human-factors tests and to involve
`human-factors specialists in the design process. When the system is imple-
`mented, collect usage data, error statistics, and subjective reactions to guide
`refinement.
`Whenever possible, use software tools to produce and display a menu,
`form fillin, or dialog box. Commercial systems reduce implementation time,
`ensure consistent layout and instructions, and simplify maintenance.
`
`7.10 Researcher's Agenda
`
`Experimental research could help to refine the design guidelines concern-
`ing organization and sequencing in single and linear sequences of menus.
`How can differing communities of users be satisfied with a common orga-
`nization when their information needs are markedly different? Should