Interaction Style Categories. COSC 3461 User Interfaces. What is a Command-line Interface? Command-line Interfaces

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1 COSC User Interfaces Module 2 Interaction Styles What is a Command-line Interface? An interface where the user types commands in direct response to a prompt Examples Operating systems MS-DOS Unix Applications ftp telnet Command-line Interfaces This was the first interaction style Still widely used Provides a means to express commands to a computer directly May use function keys, single characters, abbreviations, or whole-word commands Primarily used today for older applications (e.g., telnet)

2 Command-line Interfaces (2) Advantages Direct access to system functionality Flexibility through options or parameters that modify behaviour of commands Useful for repetitive tasks Good for expert users Disadvantages Arcane syntax difficult for novices Options difficult to remember Guidelines for Good Command-line Interfaces Commands should use vocabulary of the user, not of the technician or system Consistency from one command to the next Menu-based Interaction Options displayed on the screen Used on text-based and GUI-based systems Options may be numbered Shortcuts/accelerators possible Just type the first letter or a unique letter of a command Use TAB or arrow keys to navigate menu options

3 Menu-based Interaction (2) Advantages Since options are visible, they are less demanding on the users memory (Relies on recognition, rather than on recall) Disadvantages Can only support a small number of options Designing Menu-based Interactions Make menu options meaningful in the user s language Logically group similar options to aid recognition Use hierarchical organization (sub-menus) where appropriate Natural Language Interaction At first glance, a very attractive mode of interaction Scenario: The user cannot remember command or is lost in hierarchy of menus The cure: natural language understanding Speech, printed / written, sign-language Subject of considerable interest and research

4 Difficulty of Natural Language Parsing language is very difficult The man hit the boy with the stick. (who has the stick?) Words are vague or ambiguous exit vs. close (are they the same?) Homonyms exacerbate speech input caret vs. carrot (same sound, different meaning) Spelling errors and variations exacerbate problem disk vs. disc, color vs. colour, center vs. centre Converting audio speech to machine-readable text is very difficult! (segmentation problem, response time) Emotion exacerbates recognition problem Promise of Natural Language Interaction Relatively successful in restricted domains (but, is this natural language?) User must learn phrases that work (and that don t) But language is, by it s very nature, vague and imprecise, and this promotes flexibility and creativity, but computers require precise language User is asked a series of questions Usually with yes/no responses or multiple choices Think of a Wizard Constraining answers means input is easily parsed by the application Easy for user to learn, but limited in functionality Appropriate for restricted domains

5 Query Languages Used to construct queries for databases Appears to use natural language phrases SQL example SELECT Students.LastName, Students.FirstName, Students.Faculty FROM Students WHERE Students.Faculty="arts"; But, in fact, Specific syntax is required, As well as knowledge of database schema, And a knowledge of Boolean operators Not well-suited for novices Query vs. Natural Language Distinction is sometimes blurred What appears as a natural language interface may simply be a front for a query system E.g., MS Word Question parsed into keywords to form query Used primarily for data entry User is presented with a display resembling a paper form (often based on actual form) User already familiar with actual form (aides memory) Requires correction facility, and easy navigation, because users change their minds or notice mistakes later Good for novice or expert users

6 Spreadsheets for Forms Can be used as sophisticated forms Grid of cells, cells have formulae Data may be added in any order System maintains consistency and updates values immediately User can manipulate values and observe effects Blurs distinction between input and output Attractive medium for forms Spreadsheet Example = Qty * Unit Price = Windows, Icons, Menus, Pointers Currently the most common environment for interactive computing Examples: Microsoft Windows, Apple MacOS, X-Windows

7 Example Hybrid Interaction Styles X-Windows on top of UNIX mixes the old and new Old systems are often called legacy systems Legacy systems are very hard to replace or update, due to investment and momentum Adage: If it ain t broke, don t fix it! The old: command-line interaction The new: WIMP Example of Hybrid interaction: Command-line interaction in a window In multimedia systems (e.g., web browsers), most interactions require only a single click of a mouse button Closely related to WIMP (i.e., buttons are also used in WIMP interfaces) Point-and-click philosophy is simpler Closely related to hypertext idea Not limited to mouse, information kiosks often have a touch screen instead Popularized by WWW pages

8 Increasing use of 3D in user interfaces Common examples Virtual reality Immersive environments Games Beyond WIMP Effects 3D also used for more complex workspaces Objects displayed in 2D with perspective Beyond WIMP Effects (2) 3D workspaces pose serious interaction problems Not for novices Output appears in 3D, but input is still the keyboard and mouse Problems in navigation, object manipulation, scene manipulation Systems tend to be highly moded Must think about degrees of freedom

9 3D = 6 Degrees of Freedom The Future Eye Tracking y z x 6 Degree of Freedom Tracking (Polhemus) Haptics (Phantom) The Future Ubiquitous Computing Next topic Direct neural interfaces