AS Level ICT - Topic 9 HCI

The Need for Effective Dialogue Between Humans and Machines

- User needs to be able to give instructions to the device to tell it what to do and the device needs to tell user what to do or about a problem

 - Standard interface for the human inputting data into the computer is via the keyboard with computer giving its response on the screen -> Process control screens, digital TVs, mobile phones, computer games, cockpit controls on fly-by-wire aircraft, and information systems all make use of innovative user interfaces

Appropriate Interface Design to Provide Effective Communication for Users

- Playing a game e.g. Formula One racing car, you would want the game to be as realistic as it can -> Better interface would be to use a joystick, gear sticks and foot pedals

The Need to Design Human-computer Interfaces that Take into Account the Task, User Experience, User Preference and Resources

Task - Different tasks require different human-computer interfaces e.g. someone using a CAD workstation will usually have attended training courses on how to use the software, they will be using the software daily so their requirement will be to produce the diagrams and plans in the least amount of time -> They will want to have as much on the screen as possible, so it doesn't matter if the screen is cluttered as they are used to it

User Experience -> Experienced user will want to complete tasks quickly whereas beginners won't be too bothered

User Preference -> Experienced users may like to give commands at the keyboard if it's quicker and a majority of software offer different ways of using it so it satifies everyone

Resources -> Sophisticated human-computer interfaces require more processing power and memory and this could be an issue with older computers

General Features of the Human-computer Interface

Use of Appropriate Input Methods -> Reduce use of keyboard to avoid RSI, ergonomic keyboard, ergonomically designed mouse, reduce no. of mouse movements

Use of Colour -> Pastel shades are easier on the eye, appropriate text and background colour, avoid using certain colours, colours make things easier to learn

Consistency -> Consistency between similar pages to make system easier to learn, similar pieces of software in same range for same reason and objects should be placed in same place

Use Picture / Icons -> Young children, help children choose correct option + easier to learn

Use of Text -> Font easy to read, appropriate font size, appropriate language, don't give members too much to remember

Sound -> More interesting, allow it to be turned off and it is vital for partially sighted users

Command Line / Driven Interfaces

- Interfaces where you have to type in commands in a certain language for the computer to do something

Advantages - Quicker than using a mouse and all the features of Windows

Disadvantages - Difficult for beginners to use and you have to remember the instructions

Graphical User Interfaces (GUIs)

- Popular as they are easy to use because you only have to point and click at objects on the screen e.g. Microsoft Windows and Macintosh OS

 - Features: Windows, icons, menus, pointers, a desktop, drag and drop, and taskbars

Advantages - No language needed, use of icons, easier to use a mouse

Disadvantages - More memory required and increased processing requirements

Menu-driven Interfaces

Advantages - Simple interface which is very easy to use

Disdvantages - Only suitable where there are a few items to choose from on the menu

Form-driven Interfaces

- Used to collect info from a user in a step-by-step manner

 - User supplies information by typing it into a form and validation checks make sure that the customer only enters valid data into the form and that all the important fields are completed

Natural Language Interfaces

- Allows user to interact using natural written or spoken language

 - Advantage is that learning how to use it is easy but natural language is ambiguous so language needs to be restricted to certain words

Voice Interfaces

Voice / Speech Recognition Systems -> Allows you to enter data via a microphone -> Need a computer, a microphone and voice recognition software

Advantages of Voice Recognition - Faster than typing, 99% accuracy, cheap

Disadvantages of Voice Recognition - Takes a while to get used to, not accurate at first, errors due to background noise and doesn't work with all database software

Speech Synthesis -> Allows a computer to read text that has been typed in or it can be used to give a response e.g. direction instructions in a satellite navigation system

Graphical Devices

- Pen tablet works like using a pen and paper -> Graphics pads are often used with CAD workstations or other design software -> Advantage is that all of the screen can be used as working area for the design and isn't taken up by menus, toolbars, etc.

Game-playing Devices

- Joysticks enable control of games

 - Cordless games controller makes it easier to use the game

 - Steering wheel for a racing car simulation

 - Proper clutch, brake and accelerator pedals improve the HCI

 - Gear change will make the HCI even more realistic

Output Devices -> Large plasma screens to make it life-size, surround sound speakers, gaming headset

Touch-sensitive Screens

- Used as input devices for purchasing train tickets etc. -> Advantage is that they are simple

Biometric Devices

- Identified by things like the pattern of blood vessels on the retina at the back of the eye, fingerprints, hand prints, voice and face

 - They are used for registration systems in schools and colleges, recording employees as they arrive at and leave work, limiting access to computers only to authorised staff

 - In the future they could be used for passport control and admission to clubs / bars