Input and Output Devices

I/O Devices: Input information data An input device one that, together with appropriate software, transforms information from the user into data that the computer application can process. usability Choice and method of use of an input device should contribute positively to usability of the system feedback The usability of an input device depends greatly on the provision of appropriate feedback

Types of Keyboard Qwerty Qwerty keyboard Uses most common alphabetic character arrangement Required for highly variable data entry. Many trained typists. Slow for non-typists Dvorak Dvorak keyboard Similar to Qwerty. More efficient layout Chord Chord Various arrangements. Words are formed by combinations of key presses

Keyboards (lesser known) KlockenbergMalton Klockenberg (1926) / Malton (1977) “ Ergonomic keyboard”. Varying key heights. Lessens physiological strain Palantype Palantype stenographic use Numeric keypad Numeric keypad may eliminate need for use of alphanumeric keyboard in some applications

Pointing devices pointingtracking A variety of pointing and tracking devices are available, but many are experimental userstasks Various characterstics and features may suit different users or different tasks Eyesheadsfeet hands Eyes, heads and feet can be used to control computers as well as hands

Pointing devices: cursor control 3D tracker 3D tracker Relays position and orientation to a receiver. Replaces mouse where desk space is limited (e.g., laptops) Joystick Joystick Small stick, movable in any direction in a fixed socket. Mouse Mouse continuous input device. Buttons for discrete input. Relative device. Trackball Trackball (a.k.a. “dead mouse”) Rotatable ball in fixed socket Tablet Tablet used with stylus or puck. Absolute device Mole Mole (a.k.a. “foot mouse”)

Pointing devices: Other Dataglove Dataglove Communicates hand and finger position to an application. Used for manipulating virtual objects Touch-sensitive screen Touch-sensitive screen Special screen that detects the position of a finger touching it. Light pen Light pen Location found by beam passing through screen during refresh cycle

Comparison of major devices

Developments in input Speech recognition Speech recognition advantages: minimal user training, freedom of hands etc., opportunities for physically disabled disadvantages: recognition system often needs training, liable to error; subject to interference from background noise; difficult for application to interpret human speech Handwritten input Handwritten input advantages: easier to separate words, may need some training for users disdavantages: cursive script difficult to read, wide variety of handwriting styles, system may need training

Output devices feedback Output devices provide information or feedback in a form which is understandable by humans Visual Display Unit Visual output, in 2-D, using a Visual Display Unit (VDU) is by far the most common form. Progress has been in the direction of matching the colour- awareness of the human eye New trends and possibilities include Graphical User Interfaces (GUIs) Output devices suitable for laptop or notebook-size hardware Multimedia

Visualisation Dynamic visualisation Dynamic visualisation is becoming increasingly important in information-rich applications visualisation of data, processes, scientific phenomena mental model The key issue is finding visual forms that support the users’ mental model Perceptualisation “Perceptualisation” is the multimedia equivalent of visualisation Virtual Reality 3-D animation and Virtual Reality are likely to increase in importance for “perceptual” interfaces

Sound Sounds Sounds can complement a visual interface when the users’ attention is likely to turn away from a VDU screen “background” events An important use is to deliver information on “background” events that need continual monitoring information overload The “seven plus or minus two” rule for information overload applies to sounds, too visually disabled Sound can be critically important in interfaces for the visually disabled

Digital speech techniques Concatenation Concatenation involves digitally recording human speech in large chunks (words, short sentences) and reassembling it and playing back e.g., “talking clock” Synthesis-by-rule Synthesis-by-rule involves synthesizing speech according to prescribes rules of sound formation to generate more “natural-sounding” tone, pitch, rhythm

Issues Involving Vision Range Total blindness Impaired vision Color blindness Photosensitive epilepsy Technologies: Screen readers Braille Descriptive audio Don’t use tables in HTML to control layout; use tags to identify table cells and headers

Screen reader Narrates (reads aloud) the text on the screen Important considerations: HTML must note change in language, e.g., English to Spanish, using the “lang” attribute HTML tables must not be used to control layout: doing so makes the narration difficult to understand HTML tables used to display tabular material need additional markup to make the meaning clear

One form of Braille, with contractions

Refreshable Braille display

A screen magnifier: the right portion here

Color blindness 8% of the male population There are three kinds, one of which is extremely rare The most common type is deuteranopia, commonly called red/green confusion The following slides show how some colored materials would look to a color blind person, simulated by software from Vischeck, Inc.

Do you prefer red peppers or green peppers? How would you pick?

What is a green salad?

A color wheel, to the color blind

How do traffic lights look to a color blind driver? So: learn that red is always on top Always? Are you sure?

Is red on the right or left? Did you get it right? Are you sure we got it right, or is the red sometimes on the other side?

The worst

Issues Involving Mobility Impairment As applies here: any conditions that affects a person’s ability to use keyboard and mouse Can be caused by: Diseases: arthritis, muscular dystrophy, multiple sclerosis Stroke Injury Loss of limb Repetitive strain injury Natural aging processes

Assistive technologies available in Windows StickyKeys permits one-finger typing Press Shift, Ctrl, or Alt followed by another key, rather than pressing two keys at same time FilterKeys helpful for people with hand tremors or problems with fine-motor control Ignores brief or repeated keystrokes MouseKeys permits moving pointer with the numeric keypad SerialKey permits access, via serial port or USB port, to alternatives for mouse and keyboard functions Foot mouse

Predictive typing

The Eyegaze TM system

Eyegaze ® A video camera tracks eye movement as the user looks at an on-screen keyboard Customizable as to how long a key must be looked at to be recorded When system has identified the key looked at, the symbol appears and the user looks at next key

Issues Involving Hearing Impairment Deafness Hard of hearing; can be helped by hearing aids Can be caused by prolonged exposure to noisy environments Hearing often degrades with age

Closed captioning

An avatar signs from English text See asl.cs.depaul.edu for more information and a demo. The project is led by Dr. Rosalee Wolfe.

The Web Accessibility Initiative The World Wide Web Consortium (W3C) is committed to promoting usability for people with disabilities The goal: Universal access. Everyone. Must take into account user agents other than browsers: mobile phones, PDAs, screen readers and magnifiers, etc. Not easy; not free It’s simply the right thing to do

Multimedia The potential for multimedia includes the fact that it is estimated that only 7% of business-critical information is “record-based” Multimedia databases including photos, video clips, sounds, animation etc., may permit digitalisation of much of the other 93% Object Technology is a critical technical enabler for such advances

Animation Definition: synthetic apparent motion created through artificial means Can sometimes be stored more compactly than video, speeding downloads Offers a richer set of interactions than video An attention-getter Good for demonstrating transitions and for explaining complex systems

Using animation to focus attention, 1

Using animation to focus attention, 2

Tour of the Munich Airport Center, in interactive 3D, 4

An avatar

Level of detail, 1

Level of detail, 2

Level of detail, 3

Choosing appropriate devices work Matching devices with work The particular manipulations needed to accomplish a piece of work need to be analyzed Natural mappings between use, feedback, meaning of result and user’s mental model are needed users Matching devices with users e.g., eye and head input for the physically disabled environment of use Matching devices with environment of use space relation to other concurrent tasks etc.,