Human Computer Interaction

1. Human Computer Interaction Week 5 Interaction Devices and Input-Output

2. Introduction • Current Input/Output Devices: • Keyboard, Mouse, CRT or LCD displays, Printers. • Future Input/Output Devices: • Gestural Input, 3-D pointing, more voice input/output, wearable devices, whole body involvement for some input/output tasks.

3. Text Input Devices • Text Input, implemented by: • Keyboard • Speech Recognition • Handwriting • Gloves

4. Pointing Input Devices • Pointing, implemented by: • Mouse • Touch Screen • Track-Ball • Eye-Tracking

5. The Choice of Input Device • The choice of input device should contribute as positively as possible to the usability of the system. It should be the one that: • Matches the physiological and psychological characteristics of users, their training and their expertise. • Is appropriate for the tasks that are to be performed. • Is suitable for the intended work and environment. • There must also be adequate and appropriate system feedback to guide, reassure, inform and, if necessary, correct users’ errors.

6. Keyboard • Keyboard is a discrete entry device. • Keyboard types: • Qwerty keyboard:- the most common keyboard.- derived from typewriters (1874).- designed to avoid keys jamming in manual typewriters. • Dvorak keyboard: - first patented in 1932.- more efficient input than Qwerty.- not commercially successful. • Chord keyboard:- press several keys at once to enter one character. - training is required.

7. Pointing devices • Pointing devices are continuous entry devices. • Examples: • Mouse • Trackball • Joystick

8. Touch Screen • Touch Screen allows the user to input information into the computer simply by touching an appropriate part of the screen or a touch-sensitive pad near to the screen. • Advantages: easy to learn, require no extra work space, have no moving part. • Disadvantages: lack of precision, high error rates, arm fatigue, finger obscuring detail on the screen and screen smudging. • Best for large targets and untrained users.

9. Speech Input • Advantages: • Easier to learn (natural communication). • Does not require the use of hands. • Offers disabled people to use computers. • Disadvantages: • Applied only in very specialized and highly constrained tasks. • Speech recognizers have severe limitations. • Speech recognizers are subject to interference. • Natural language used by people is very difficult for a computer to interpret.

10. Two Main Aspects of Input Devices • Direct vs. IndirectDevice’s physical movement directly correspond to the reaction on the screen. • Absolute vs. RelativeDevice’s location directly control the object’s location and reaction on the screen.

11. Taxonomy of user-centered pointing devices

12. Task - Device • Numeric Data Entry: Numeric Keypad • Text Data Entry: Alphanumeric Keyboard • Object Selection (e.g. icon selection): Mouse, TrackBall • Object Manipulation (e.g. drag & drop): Mouse, TrackBall • Tracking (e.g. drawing): Mouse, LightPen

13. Output Devices (1) • Printed Output • Laser Printer, Ink Jet, Impact and Thermal Printer • Graphical Output • CRT or LCD displays, projectors

14. Output Devices (2) • Audio Output • Stereo/Surround Speakers, Headphones

15. Sound Output • Current uses: alerting and feedback. • Different kinds of sound: • Speech • Musical Sounds • Natural Sounds

16. Sound output has already proved valuable • Complements visual interface • When the users are visually occupied • Monitoring background processes • Addressing the needs of blind users • Data Sonification • Algorithm Animation

17. Types of Sound Output • Natural Sound: Gaver, uses everyday sounds to convey computer objects / events, called auditory icons. Example: Sonic Finder (1989). • Musical Sound: Blattner, uses musical tones to convey computer objects / events, called earcons. • Speech Output: The most obvious means of using sound.

18. Further Reading • Preece, chapter 11,12