Chapter 6: The Computer & Interaction Styles
Definition
- Hardware components that allow users to provide data or control signals to a computer system.
Causes
Goals / Objectives
- Enable efficient, accurate, and accessible user input for a range of tasks.
Importance
- Fundamental to human-computer interaction; choice of input device affects usability, speed, and accessibility.
Benefits
- Supports diverse interaction needs (text, pointing, voice, etc.).
- Enables task-specific optimization (e.g., touch for kiosks, keyboard for text).
Procedures
- Not specified as a unified process; each device operates via its own mechanism (e.g., keypress, touch detection).
Advantages & Disadvantages
- Not specified in notes as a general comparison; detailed per device in subtopics.
Impact / Effect
- Poor input device choice can hinder performance or exclude users.
- Appropriate devices enhance efficiency and user satisfaction.
Examples
- Keyboard, mouse, touchscreen, stylus, microphone, camera, scanner, trackball.
Keyboard
Definition
- A standard input device for entering text, typically using the QWERTY layout.
Causes
- Historical design constraints from typewriters influenced modern layouts.
Goals / Objectives
- Allow rapid text entry for experienced users.
Importance
- Remains the primary text input method for most computing tasks.
Benefits
- Enables fast, precise text input for trained users.
Procedures
- Pressing a key closes an electrical connection, sending a character code to the system.
Advantages & Disadvantages
- Advantages:
- Allows rapid text entry for experienced users
- Disadvantages:
- QWERTY layout is not optimal for typing
- Biased toward left hand (57% vs. 43% right hand usage)
Impact / Effect
- Suboptimal layouts may increase fatigue and reduce typing efficiency.
Examples
- QWERTY: Standard layout (invented by Sholes, 1868).
- Dvorak: 1920s layout placing common letters under dominant fingers; 10–15% faster with less fatigue; right-hand biased (56%).
- Alphabetic: Keys in A–Z order; used in handheld devices but not faster for beginners or experts.
Stylus
Definition
- A pen-like input device used to write or draw directly on a screen or tablet.
Causes
- Need for compact, intuitive text or drawing input without a keyboard.
Goals / Objectives
- Enable direct, natural input for handwriting or sketching.
Importance
- Useful in mobile or space-constrained environments.
Benefits
- Requires no training; compact and portable.
Procedures
- User writes with stylus; system uses recognition software to convert input to digital text.
Advantages & Disadvantages
- Advantages:
- No training needed
- Compact size
- Disadvantages:
- Relatively low recognition accuracy
Impact / Effect
- Recognition errors may frustrate users or reduce efficiency.
Examples
- Handwriting input on tablets or PDAs.
Mouse
Definition
- A handheld pointing device that detects 2D motion relative to a surface.
Causes
- Need for precise, continuous control of on-screen cursors.
Goals / Objectives
- Enable easy selection, navigation, and manipulation of interface elements.
Importance
- One of the most common input devices for desktop computing.
Benefits
- Supports diagonal and continuous movement; intuitive for most users.
Procedures
- User moves mouse on surface; optical or mechanical sensors track motion and update cursor position.
Advantages & Disadvantages
- Advantages:
- Allows diagonal and continuous movement
- Easy to use
- Disadvantages:
- Requires hand to be removed from keyboard
Impact / Effect
- Enhances direct manipulation interfaces but interrupts typing flow.
Examples
- Mechanical, optical, laser, and wireless mice; even foot-operated variants.
Trackball
Definition
- A stationary pointing device with a rotatable ball on top that controls cursor movement.
Causes
- Need for pointing in confined spaces or for users with limited desk area.
Goals / Objectives
- Provide mouse-like control without requiring large surface movement.
Importance
- Alternative for users with mobility constraints or limited workspace.
Benefits
- Enables precise cursor control in small physical footprints.
Procedures
- User rotates the ball with fingers or palm; internal sensors translate motion to cursor movement.
Advantages & Disadvantages
- Advantages:
- Allows diagonal and continuous movement
- Requires less physical space than a mouse
- Disadvantages:
- Requires hand to be removed from keyboard
Impact / Effect
- Useful in industrial or embedded systems where space is limited.
Examples
- Trackballs on kiosks, CAD workstations, or assistive devices.
Touchscreen
Definition
- A display that detects the presence and location of a touch (typically by finger or stylus).
Causes
- Demand for direct, intuitive interaction without intermediary devices.
Goals / Objectives
- Enable fast, direct selection and navigation, especially for non-expert users.
Importance
- Dominant input method for mobile and public-facing systems.
Benefits
- Direct interaction (no mouse needed); fast for menu selection; minimal training required.
Procedures
- Touch is detected via capacitive, resistive, or perimeter-based (light/sound wave) technologies.
Advantages & Disadvantages
- Advantages:
- Direct interaction
- Fast
- Good for menu selection
- Disadvantages:
- Leaves fingerprints
- Hand obscures screen
- Can be tiring for prolonged use
Impact / Effect
- Ideal for kiosks or retail but less suited for extended text input or precision tasks.
Examples
- Tourist information kiosks, cashier systems, smartphones.
- Types:
- Capacitive: More responsive (used in smartphones)
- Resistive: Less sensitive, pressure-based
- Perimeter-based: Converts existing displays to touch via sensors
Output Devices Overview
Definition
- Hardware that conveys information from the computer to the user.
Causes
Goals / Objectives
- Present system output in accessible, usable formats (visual, auditory, tactile).
Importance
- Critical for user awareness, feedback, and accessibility.
Benefits
- Supports multimodal interaction and inclusive design.
Procedures
- Varies by device type (e.g., screen refresh, audio playback, pin actuation).
Advantages & Disadvantages
- Not specified in notes as a general comparison; detailed per device.
Impact / Effect
- Poor output design can exclude users or reduce comprehension.
Examples
- Computer screens (CRT, LCD, OLED), speakers, Braille displays, printers.
CRT (Cathode Ray Tube) Displays
Definition
- An older display technology using electron beams to illuminate phosphors on a screen.
Causes
- Historical standard before flat-panel technologies matured.
Goals / Objectives
- Provide high-quality visual output with accurate color and fast response.
Importance
- Once the dominant display type; now largely obsolete.
Benefits
- High resolution, accurate color, fast response, wide viewing angles.
Procedures
- Electron gun scans screen line by line to excite phosphor dots.
Advantages & Disadvantages
- Advantages:
- High resolution
- Accurate color balance
- Fast response time
- Better viewing angle
- Disadvantages:
- Bulky and heavy
- Emits radiation
- Impractical for screens larger than 40 inches
Impact / Effect
- Replaced by lighter, safer flat-panel displays in most applications.
Examples
- Old desktop monitors and televisions.
LCD (Liquid Crystal Display)
Definition
- A flat-panel display technology using liquid crystals to modulate light.
Causes
- Demand for lighter, energy-efficient, and compact displays.
Goals / Objectives
- Deliver clear visual output with reduced size and power consumption.
Importance
- Widely used in laptops, monitors, and mobile devices.
Benefits
- Compact, energy-efficient, flicker-free, and radiation-free.
Procedures
- Liquid crystals twist to block or allow light from a backlight through color filters.
Advantages & Disadvantages
- Advantages:
- Smaller and lighter
- No radiation emission
- Lower power consumption
- Flicker-free
- Disadvantages:
- Less accurate color reproduction
- Lower response time (potential motion blur)
Impact / Effect
- Enabled portable computing and widespread digital displays.
Examples
- Laptop screens, office monitors, digital signage.
Speech Output
Definition
- Auditory system output using human-like or synthetic voice.
Causes
- Need to support users who cannot use visual displays or have visual impairments.
Goals / Objectives
- Convey information via spoken language in accessible contexts.
Importance
- Enhances accessibility and supports multitasking (e.g., eyes busy).
Benefits
- Useful when eyes are occupied or for visually impaired users.
Procedures
- Uses either:
- Digitized speech: Pre-recorded human voice (e.g., “The number you dialed…”)
- Synthesized speech: Computer-generated voice via text-to-speech engines
Advantages & Disadvantages
- Advantages:
- Useful when eyes are busy or user is visually impaired
- Disadvantages:
- Slow pace compared to visual output
Impact / Effect
- Should be avoided in noisy or public environments due to privacy and clarity issues.
Examples
- Public transit announcements (“Next station: Bangsar”), screen readers.
Audio (Non-Speech Sound)
Definition
- Use of non-verbal sounds (beeps, tones, music) as system feedback or ambiance.
Causes
- Need for immediate, attention-grabbing cues without visual overload.
Goals / Objectives
- Provide feedback, warnings, or contextual mood.
Importance
- Complements visual feedback; enhances user experience in games and alerts.
Benefits
- Immediate and intuitive for simple signals.
Procedures
- System triggers sound files or synthesized tones based on events.
Advantages & Disadvantages
- Not specified in notes beyond general use.
Impact / Effect
- Effective for confirmation or warning but can be disruptive if overused.
Examples
- Button click sounds, error beeps, game background music.
Braille Display
Definition
- A tactile output device that raises and lowers pins to form Braille characters.
Causes
- Need for accessible output for blind users.
Goals / Objectives
- Provide real-time text output in Braille for visually impaired users.
Importance
- Critical accessibility tool for blind computer users.
Benefits
- Enables independent reading of digital text.
Procedures
- Electromechanical pins are raised/lowered to represent Braille cells (6 or 8 dots).
Advantages & Disadvantages
- Not specified in notes beyond basic function.
Impact / Effect
- Supports literacy and computer access for blind individuals.
Examples
- Refreshable Braille displays connected to screen readers.
Haptic Feedback
Definition
- Tactile feedback (vibration, force, motion) provided through input/output devices.
Causes
- Need to simulate physical interaction in virtual environments.
Goals / Objectives
- Enhance realism and provide non-visual confirmation of actions.
Importance
- Adds a physical dimension to digital interaction.
Benefits
- Improves immersion and usability in virtual or remote tasks.
Procedures
- Devices like the Geomagic Touch X apply resistance or vibration based on virtual object properties.
Advantages & Disadvantages
- Not specified in notes beyond mention of device example.
Impact / Effect
- Used in training simulators, gaming, and assistive tech.
Examples
- Geomagic Touch X haptic device for virtual manipulation.
Interaction Types (Rogers, Sharp & Preece)
Definition
- Four conceptual models describing how users interact with systems: Instructing, Conversing, Manipulating, and Exploring.
Causes
- Different tasks and user needs require different interaction paradigms.
Goals / Objectives
- Match interaction style to user capabilities and task demands.
Importance
- Guides interface design for optimal usability and user experience.
Benefits
- Helps designers choose appropriate interaction models for specific contexts.
Procedures
- Not a step-by-step process; a framework for design decisions.
Advantages & Disadvantages
- Not specified as a unified comparison; detailed per type.
Impact / Effect
- Mismatched interaction styles can confuse or frustrate users.
Examples
- Hybrid interfaces often combine multiple types (e.g., voice + touch).
Instructing
Definition
- Users issue explicit commands or select options to tell the system what to do.
Causes
- Need for precise, repeatable control over system functions.
Goals / Objectives
- Support efficient execution of known tasks.
Importance
- Foundation of traditional computing (e.g., CLI, menus).
Benefits
- Enables quick, efficient interaction for repetitive actions.
Procedures
- User types commands or selects from predefined options.
Advantages & Disadvantages
- Advantages:
- Supports quick and efficient interaction
- Good for repetitive actions on multiple objects
- Disadvantages:
- Not specified in notes for this type alone
Impact / Effect
- Best suited for expert users or batch operations.
Examples
- “Save file”, “Print document”, Unix commands like
cp or mkdir.
Conversing
Definition
- Interaction modeled as a dialogue, using natural or structured language.
Causes
- Desire to make systems feel more human-like and approachable.
Goals / Objectives
- Reduce intimidation for novices or non-technical users.
Importance
- Increases accessibility for children, elderly, or technophobic users.
Benefits
- Feels familiar and comfortable; lowers entry barrier.
Procedures
- User speaks or types; system parses input and responds conversationally.
Advantages & Disadvantages
- Advantages:
- Familiar interaction style for novices and technophobes
- Makes users feel comfortable and less scared
- Disadvantages:
- Misunderstandings occur if system can’t parse user input
Impact / Effect
- Errors in understanding can break the interaction flow.
Examples
- Chatbots, voice assistants (e.g., Siri), phone-based IVR systems.
Manipulating (Direct Manipulation)
Definition
- Users interact with on-screen objects as if they were physical (e.g., drag, zoom, rotate).
Causes
- Inspired by computer games and desire for intuitive control (Shneiderman, 1983).
Goals / Objectives
- Give users a sense of control, visibility, and reversibility.
Importance
- Core of modern GUIs; enhances user confidence and reduces anxiety.
Benefits
- Immediate visual feedback; actions are reversible; users feel in control.
Procedures
- User uses pointing device (mouse, finger) to directly act on visual objects.
Advantages & Disadvantages
- Advantages:
- Users experience less anxiety
- Gain confidence, mastery, and sense of control
- Disadvantages:
- Not all actions can be done directly (e.g., spell checking)
- May exclude visually impaired users
- Slower for repetitive tasks vs. CLI
Impact / Effect
- Highly engaging for “doing” tasks (design, navigation) but not universal.
Examples
- Dragging files, resizing windows, using drawing apps.
Exploring
Definition
- Users navigate through virtual or information spaces to discover content.
Causes
- Natural human tendency to browse and discover rather than query.
Goals / Objectives
- Support open-ended discovery and information foraging.
Importance
- Mirrors real-world exploration; suits multimedia and web contexts.
Benefits
- Encourages engagement and serendipitous discovery.
Procedures
- User moves through environments (e.g., websites, 3D worlds) via links, menus, or spatial navigation.
Advantages & Disadvantages
- Not specified in notes beyond description.
Impact / Effect
- Effective for learning, entertainment, and information-rich systems.
Examples
- Browsing the web, exploring a museum app, navigating a game world.
Interface Types Overview
Definition
- Distinct styles of user interfaces that support different interaction models.
Causes
- Evolving user needs, technology capabilities, and task requirements.
Goals / Objectives
- Provide appropriate interaction paradigms for different contexts and users.
Importance
- Choosing the right interface type is critical for usability.
Benefits
- Each type excels in specific scenarios (e.g., CLI for experts, forms for data entry).
Procedures
- Designers select or combine interface types based on task analysis.
Advantages & Disadvantages
- Covered in detail per interface type.
Impact / Effect
- Hybrid interfaces are common but may increase learning time.
Examples
- Command Line, Direct Manipulation, Menu, Fill-in Form.
Command Line Interface (CLI)
Definition
- Text-based interface where users type commands in a structured artificial language.
Causes
- Early computing limitations and need for precise, scriptable control.
Goals / Objectives
- Enable powerful, efficient control for expert users.
Importance
- Still used in system administration, development, and automation.
Benefits
- Extremely powerful and fast for trained users.
Procedures
- User types commands (e.g.,
cd, mkdir) with specific syntax; system executes them.
Advantages & Disadvantages
- Advantages:
- Powerful, fast, and efficient (few keystrokes for complex tasks)
- Flexible and user-controlled
- Fast for experts
- Disadvantages:
- Difficult to learn and remember
- Commands and enhancements are invisible
- Assumes typing skill
- Hardest for novices
Impact / Effect
- High efficiency for experts but high barrier to entry.
Examples
- Unix/Linux terminal, MS-DOS, PowerShell.
Direct Manipulation Interface
Definition
- GUI where users act directly on visual objects using pointing devices.
Causes
- Shift toward visual, intuitive computing in the 1980s.
Goals / Objectives
- Replace abstract commands with visible, reversible actions.
Importance
- Basis of modern desktop and mobile interfaces.
Benefits
- Immediate feedback; visible system state; low anxiety due to reversibility.
Procedures
- User selects, drags, resizes, or otherwise manipulates on-screen elements.
Advantages & Disadvantages
- Advantages:
- Immediate visibility of action results
- Actions are easily reversible (less anxiety)
- Disadvantages:
- Not all actions can be done directly (e.g., spell checking)
- Requires graphics display and pointing device
- Slower for repetitive tasks compared to CLI
Impact / Effect
- Revolutionized computing accessibility but may exclude some users (e.g., blind).
Examples
- Desktop file management, photo editing apps, touch-based mobile UIs.
Definition
- Interface presenting a list of options from which the user selects.
Causes
- Need to reduce memory load by making choices visible.
Goals / Objectives
- Support recognition over recall; simplify decision-making.
Importance
- Ubiquitous in software; reduces cognitive load for common tasks.
Benefits
- Options are visible; easier to use; enhancements (new features) are immediately apparent.
Procedures
- User navigates hierarchical or contextual menus via mouse, touch, or keyboard.
Advantages & Disadvantages
- Advantages:
- Options visible
- Less recall required (easier to use)
- Enhancements are visible
- Disadvantages:
- Inflexible—forces users through set sequences
Impact / Effect
- Poor menu design (e.g., deep hierarchies) can frustrate users.
Examples
- Menu bars, dropdowns, context menus, pie menus.
- Menu Types:
- Menu bar: Top-of-screen dropdowns
- Contextual menu: Appears near selected object (right-click)
- Pie menu: Circular layout; larger targets, faster selection (but rarely used)
- Gray out inactive items.
- Use familiar, distinct terminology.
- Order items by: alphabetical, categorical, conventional (e.g., months), or frequency of use.
- Apply Accot-Zhai Steering Law: Wider, shorter menu paths reduce selection time.
Definition
- Screen layout mimicking a paper form, with labeled fields for user input.
Causes
- Need for structured, efficient data entry (e.g., registration, applications).
Goals / Objectives
- Collect specific data efficiently while providing context.
Importance
- Standard for e-commerce, surveys, and administrative tasks.
Benefits
- Efficient screen use; provides contextual grouping; enhancements visible.
Procedures
- User fills fields using keyboard; navigates via Tab/Enter; submits when complete.
Advantages & Disadvantages
- Advantages:
- Efficient use of screen space
- Provides context (multiple fields visible)
- Enhancements are visible
- Disadvantages:
- Assumes typing skill
- Prone to user errors
- Assumes knowledge of special keys (Tab, Enter, Backspace)
Impact / Effect
- Poor error handling or layout can lead to abandonment or mistakes.
Examples
- Online registration forms, credit card payment pages.
- Organization & Layout:
- Mirror paper form layout if applicable
- Use spacing, lines, or color to group related fields
- Minimize label-to-field distance
- Caption & Field Design:
- Place labels above fields (better than left-aligned)
- Mark mandatory fields (e.g., with “*”)
- Avoid ALL UPPERCASE (13% slower to read)
- Right-align numeric fields; align decimals
- Error Handling:
- Show clear, specific error messages
- Completion Signal:
- Make submission action obvious (e.g., “Submit” button)