Human-Computer Interaction: Chapter 2 - The Computer

Human-Computer Interaction: Chapter 2 - The Computer

• Understanding human-computer interaction requires understanding computers.

• Computers process information, and input/output via devices (e.g., sensors).

• A computer system consists of various elements.

• Input devices include text entry and pointing tools.

• Output devices include screens, large displays, digital paper, and virtual reality-based displays.

• Physical interaction uses various elements (sound, haptic, bio-sensing).

• Output uses paper (printouts), and input/output includes scanned paper, memory (RAM), and permanent media.

• Processing speed and networks are important factors.

• Different input devices result in distinct interaction styles.

Interactivity

• Older methods like batch processing (punched cards, large data files, long wait times for line printer outputs) are now outdated.
• Modern computing is more interactive, providing rapid feedback and user control.

Richer Interaction

• Sensors and devices are becoming more prevalent in the environment.

Text Entry Devices

• Keyboards (QWERTY and others) are common, allowing fast text entry for experienced users.
• Keypresses generate character codes.
• Keyboards can be wired or wireless.
• QWERTY arrangements are standardized and historically used to prevent typewriters from jamming.

Keyboard Layouts

• QWERTY is a standardized keyboard layout.
• Non-alphanumeric keys are placed differently.
• Minor differences exist between UK and USA keyboards.
• QWERTY's layout isn't optimal for typing, but alternatives are harder to adopt due to the significant social base that uses QWERTY keyboards.

Alternative Keyboard Layouts

• Alphabetic keyboard layouts arrange keys alphabetically and aren't faster.
• They reduce fatigue by reducing RSI and repetitive strain injuries.
• Examples include the Maltron left-hand keyboard.

Chord Keyboards

• Chord keyboards use a small number of keys.
• Letters are represented by a combination of keystrokes.
• This offers a compact size.
• They are ideal for portable applications and have a short learning time.
• They reflect letter shape, and are fast.
• Still, social resistance and fatigue after use are drawbacks.
• They are a niche market for some wearables.

Phone Pad and T9 Entry

• Using numeric keys with multiple presses allows for fast text entry.
• T9 predictive entry uses a dictionary of words to guess the words most likely to be intended.
• Using dictionary lookup reduces errors and improves typing accuracy.

Handwriting Recognition

• Digitizing tablets allow handwriting-based input.
• Challenges in this method include capturing information correctly from handwriting, segmenting individual letters, and understanding diverse handwriting styles.

Speech Recognition

• Speech recognition technology is improving.
• Recognition accuracy is best with single users and limited vocabularies, but external noise, imprecise pronunciations, and many vocabularies, different people's voices, and large vocabularies negatively affect accuracy.

Positioning, Pointing, and Drawing

• Positioning, pointing, and drawing use tools like mice, touchpads, trackballs, joysticks, touchscreens, tablets, eye gaze, and cursors.

The Mouse (ctd)

• Mechanical mice use a ball under the mouse to track movement.
• Optical mice use an LED to measure movement.
• Indirect manipulation involves movement on the desktop to indicate movement on the computer screen or device.

Even by Foot

• Foot mice and controls are used for computer input, even though they are not common.
• Foot pedals are used in other applications (sewing machine, organ, piano).

Touchpad & Trackball

• Touchpads and trackballs are common in laptops.
• Touchpads are sensitive touch areas.
• Trackballs have a roller ball for movement.
• Trackballs are faster for gaming.

Joystick & Cursor Keys

• Joysticks are indirect pointing devices using pressure and buttons.
• Cursor keys (up, down, left, right) offer simple and low-cost input.
• Joysticks are good for games and aircraft or 3d navigation.
• Cursor keys are useful for text editing tasks.

Touch Screen

• Touchscreens detect finger/stylus presence.
• This is a direct-pointing device.
• Touchscreens are convenient for menu selections in hostile environments but can be slightly less precise.

Stylus and Light Pen

• Stylus is a pen-like pointer with direct screen interaction.
• Light pens are rarely used.
• They use light from the screen to detect location, but can obscure the screen.
• Digitizing tablets and PDAs use them.

Eyegaze

• Eyegaze controls interfaces via eye gaze direction.
• Users select menu items by looking at them.
• Eyegaze uses laser beams reflected off the retina and has potential for hands-free control and high accuracy, although it is expensive.
• Eyegaze is used in VR and AR applications.