MODULE 1 Human Computer Interaction. (Engineering)

This ppt is about Human Computer Interaction. Its a part of Software development where you get to know how people interacts with the computer and how computer understands and reply to their request.

1. CSG2003 Human Computer Interaction School of Computing Science and Engineering VIT Bhopal University 1

2. Unit - 1 Basic of HCI 2 Definition of HCI - Evolution of HCI - Input/output Channels - Human Memory - Thinking: Reasoning and Problem Solving - Psychology and Design of Interactive System: Models to support design - Techniques for evaluation - Computer: Text Entry Devices - Pointing and Drawing - Display Devices - Devices of Virtual Reality and 3D Interaction - Physical Control - Sensors and Special Devices .

3. Introduction Systematic analysis of man machine interaction Man machine interaction – HCI -Term coined in 1980 understanding people with specific tasks understanding people who design the system usage of computers and related devices seamless for everyday work

4. Intro( contd ) Ingredients Users Computers Tasks to be accomplished Goals The system must support the users task with a focus on its usability Useful Usable Used

5. Introduction(Contd.) it is suitable for a specific task it is easy to use and, where appropriate, adaptable to the user’s knowledge and experience it provides feedback on performance it displays information in a format and at a pace that is adapted to the user it conforms to the ‘principles of software ergonomics’

6. Evolution of HCI Early computer (e.g. ENIAC, 1946)Improvement in H/W technology (vacuum tube –transistor -IC) implied massive increase in computing power

7. Evolution of HCI By mid 1950’s, researchers realized the need for VDU IBM100 – SAGE (semi automatic ground environment )

8. Evolution of HCI The development of the Sketchpad by Ivan Sutherland (1962)

9. Evolution of HCI Their group Augmentation Research Center at the SRI was responsible for many of the interaction techniques and devices that we now-a-days take for granted Introduced concept of word processor, mouse Designed NLS ( oNLine System) -1968

10. Evolution of HCI Direct Manipulation Ben Shneiderman coined the term in 1982 First successful use of the idea in Apple Mac PC (1984) Common GUI operations (move, drag etc )Reduces the chances for syntactic errors, learning for command line interfaces WYSIWYG (What You See Is What You Get)

11. Evolution of HCI HypertextThe idea was first articulated by Vannevar Bush (1945) in ”As we may think”The Memex system Ted Nelson coined the term hypertext (mid 1960’s) to denote the non-linear structure of text (in the context of reading)Related terms: hypermedia (1980’s)/multimedia

12. Evolution of HCI Computer supported cooperative work (CSCW)-1990’sComputer networks in 1960’s Society/sociology comes into picture Groupware (CSCW systems built to support users working in a group) Computer mediated communication

13. Evolution of HCI Tim Berners –Lee (CERN, 1989) was the inventor of the most popular application layer protocol (which we used synonymously with networks) The year 1991 saw the first text based browser The first graphical browser (Mosaic) came in 1993

14. Evolution of HCI Ubiquitous computing –the most active research area in HCI nowThe field originated from Mark Weiser’s vision, Xerox PARC, late 1980’s Sensor based/context aware computing (1990’s) Also known as pervasive computing

15. Key Players in HCI Users Individual group sequence Computer Desktop Large-scale computer system Non computerized parts

16. Interaction Direct Dialog with feedback and control throughout the performance of the task Indirect Batch processing or intelligent sensors controlling the environment Users interacting with the computer in order to accomplish something Key players( contd )

17. Definition Human-Computer Interaction (HCI) is a field of science that studies the design and use of computer technology . HCI focus on interfaces between people and computers and how to design, evaluate, and implement interactive computer systems that satisfy the user. “HCI involves the design implementation and evaluation of interactive systems in the context of the users task and work.”

18. Cognitive science & psychology Knowledge of users perceptual cognitive and problem solving skills Human factors & ergonomics For the users physical capabilities Sociology To help understand the wider context of the interaction Computer science To be able to adapt and build the necessary technology Multidisciplinary factors

19. Human Computer Interaction (HCI) and User Experience (UX) are interdisciplinary fields that draw on human-centered disciplines like psychology and sociology to design and develop technological products that meet human needs . Multidisciplinary factors( contd )

20. Example of HCI Interaction with a mobile app.

21. Example of HCI Browsing a website from your desktop computer.

22. Example of HCI Using internet of things (IoT) devices.

23. Benefits of HCI Simplified deployments Simplified management Easy upgrades Scalability Reliability Improved performance Agility Software-defined infrastructure

24. Types of interface Command-line

25. Menu Driven

26. Graphical user interface graphical user interface (GUI).

27. Major Components the user, task, tools / interface, the context.

28. Human Information input output visual, auditory, haptic, movement Information stored in memory sensory, short-term, long-term Information processed and applied reasoning, problem solving, skill, error Emotion influences human capabilities Each person is different

29. Vision Two stages in vision • physical reception of stimulus • processing and interpretation of stimulus

30. The Eye mechanism for receiving light and transforming it into electrical energy light reflects from objects images are focused upside-down on retina retina contains rods for low light vision and cones for colour vision ganglion cells (brain!) detect pattern and movement

31. Visual signal Size and depth visual angle indicates how much of view object occupies (relates to size and distance from eye) visual acuity is ability to perceive detail (limited) familiar objects perceived as constant size (in spite of changes in visual angle when far away) cues like overlapping help perception of size and depth

32. Visual signal( contd ) Brightness subjective reaction to levels of light affected by luminance of object measured by just noticeable difference visual acuity increases with luminance as does flicker Colour made up of hue, intensity, saturation cones sensitive to colour wavelengths blue acuity is lowest 8% males and 1% females colour blind

33. Visual signal( contd ) The visual system compensates for: movement changes in luminance. Context is used to resolve ambiguity

34. Visual signal( contd ) Optical illusions sometimes occur due to over compensation

35. Optical Illusions Ponzo illusion Muller- lyer illusion

36. Reading Several stages: visual pattern perceived decoded using internal representation of language interpreted using knowledge of syntax, semantics, pragmatics Reading involves saccades and fixations Perception occurs during fixations Word shape is important to recognition Negative contrast improves reading from computer screen

37. Reading

38. Hearing Provides information about environment: distances, directions, objects etc. Physical apparatus: outer ear – protects inner and amplifies sound middle ear – transmits sound waves as vibrations to inner ear inner ear – chemical transmitters are released and cause impulses in auditory nerve Sound pitch – sound frequency loudness – amplitude timbre – type or quality

39. Hearing( contd ) Humans can hear frequencies from 20Hz to 15kHz less accurate distinguishing high frequencies than low. Auditory system filters sounds can attend to sounds over background noise. for example, the cocktail party phenomenon.

40. Touch Provides important feedback about environment. May be key sense for someone who is visually impaired. Stimulus received via receptors in the skin: thermoreceptors – heat and cold nociceptors – pain mechanoreceptors – pressure (some instant, some continuous) Some areas more sensitive than others e.g. fingers. Kinethesis - awareness of body position affects comfort and performance.

41. Movement Time taken to respond to stimulus: reaction time + movement time Movement time dependent on age, fitness etc. Reaction time - dependent on stimulus type: visual ~ 200ms auditory ~ 150 ms pain ~ 700ms Increasing reaction time decreases accuracy in the unskilled operator but not in the skilled operator.

42. Movement( contd ) Fitts ' Law describes the time taken to hit a screen target: Mt = a + b log 2 (D/S + 1) Where a and b are empirically determined constants, Mt is movement time,D is Distance, S is Size of target targets as large as possible distances as small as possible

43. Model Human processor [Card, Maran and Newell] The perpetual system Handles sensory stimulus from the outside world The motor system Which controls the actions The cognitive system Which provides the processing needed to connect the two Each subsystem has its own processor and memory Subsystem varies based on the complexity of tasks principles of the operation dictates the behavior of the system under certain conditions

44. Comparison of human and computers Human computer Sensory systems Visual Auditory Haptic Spatial Input peripherals Keyboard, mouse Trackpad, trackball Touch surface or screens Microphones Sensors Card readers Acting systems Hands Voice Head, body Output peripherals Screen Audi()voice ,sounds Haptics VR/AR headsets Cognitive process Perception Memory

45. Human Memory A model of the structure of memory

46. Human memory( contd ) There are three types of memory function: Sensory buffers Short-term memory or working memory Long-term memory Selection of stimuli governed by level of arousal.

47. Sensory memory Buffers for stimuli received through senses iconic memory - visual stimuli echoic memory - aural stimuli haptic memory - tactile stimuli Examples “sparkler” trail – 0.5 seconds “play-back” Continuously overwritten

48. Short term memory Scratch-pad for temporary recall rapid access ~ 70ms rapid decay ~ 200ms limited capacity - 7± 2 chunks Digits are grouped in chunks – closure (successful formation of chunk) HEC ATR ANU PTH ETR EET “THE CAT RAN UP THE TREE”

49. Short term memory model [Baddeley]

50. Long-term memory (LTM) Repository for all our knowledge slow access ~ 1/10 second slow decay, if any huge or unlimited capacity Two types Episodic – serial memory of events Semantic – structured memory of facts, concepts, skills semantic LTM derived from episodic LTM

51. Long-term memory (cont.) Semantic memory structure provides access to information represents relationships between bits of information supports inference Model: semantic network inheritance – child nodes inherit properties of parent nodes relationships between bits of information explicit supports inference through inheritance

52. LTM - semantic network Items associated to each other in classes, and may inherit attributes from parent classes. This model is known as a semantic network .

53. Models of LTM - Frames Information organized in data structures Slots in structure instantiated with values for instance of data Type–subtype relationships Frame –based representation of knowledge DOG Fixed legs: 4 Default diet: carniverous sound: bark Variable size: colour COLLIE Fixed breed of: DOG type: sheepdog Default size: 65 cm Variable colour

54. Models of LTM - Scripts Model of stereotypical information required to interpret situation Script has elements that can be instantiated with values for context “John took his dog to the surgery. After seeing the vet, he left” Script for a visit to the vet Entry conditions: dog ill vet open owner has money Result: dog better owner poorer vet richer Props: examination table medicine instruments Roles: vet examines diagnoses treats owner brings dog in pays takes dog out Scenes: arriving at reception waiting in room examination paying Tracks: dog needs medicine dog needs operation

55. Script for a visit to the vet Entry conditions Conditions that must be satisfied for the script to be activated. Result Conditions that will be true after the script is terminated. Props Objects involved in the events described in the script. Roles Actions performed by particular participants. Scenes The sequences of events that occur. Tracks A variation on the general pattern representing an alternative scenario.

56. Models of LTM - Scripts Entry conditions Visit a laptop service center Maintaining/replacing your hardware Cleaning your computer Replacing failed parts Maintaining your operating system Remove unwanted applications Reinstalling your operating system Installing updates

57. Entry condition Laptop not working Roles Check by user Check by service engineer Check for visual , and audio clues for parts Tracks Provide ways for solution for problems Props Different hardware devices Results Provide a working laptop

58. Models of LTM - Production rules Representation of procedural knowledge. Condition/action rules if condition is matched then use rule to determine action. IF dog is wagging tail THEN pat dog IF dog is growling THEN run away

59. LTM - Storage of information rehearsal information moves from STM to LTM total time hypothesis amount retained proportional to rehearsal time distribution of practice effect optimized by spreading learning over time structure, meaning and familiarity information easier to remember

60. LTM - Forgetting decay information is lost gradually but very slowly interference new information replaces old: retroactive interference old may interfere with new: proactive inhibition so may not forget at all memory is selective … … affected by emotion – can subconsciously `choose' to forget

61. LTM - retrieval recall information reproduced from memory can be assisted by cues, e.g. categories, imagery recognition information gives knowledge that it has been seen before less complex than recall - information is cue numbers and associated words: 1 bun 6 sticks 2 shoe 7 heaven 3 tree 8 gate 4 door 9 wine 5 hive 10 hen

62. Thinking Reasoning - the process by which we use the knowledge we have to draw conclusions or infer something new about the domain of interest. deductive, inductive, abductive Problem solving Deductive: derive logically necessary conclusion from given premises . e.g. If it is Friday then she will go to work It is Friday Therefore she will go to work. ………. Logical conclusion not necessarily true: e.g. If it is raining then the ground is dry It is raining Therefore the ground is dry

63. Deductive Reasoning When truth and logical validity clash … e.g. Some people are babies Some babies cry Inference - Some people cry Correct? where truth and validity clash, that human deduction is poorest. People bring world knowledge into reasoning

64. Inductive Reasoning Induction: generalize from cases seen to cases unseen e.g. all elephants we have seen have trunks therefore all elephants have trunks. Unreliable: can only prove false not true … but useful! Humans not good at using negative evidence e.g. Wason's cards.

65. Wason's cards Is this true? How many cards do you need to turn over to find out? …. and which cards? 7 E 4 K If a card has a vowel on one side it has an even number on the other

66. Abductive reasoning reasoning from event to cause e.g. Sam drives fast when drunk. If I see Sam driving fast, assume drunk. Unreliable: can lead to false explanations

67. Problem solving Process of finding solution to unfamiliar task using knowledge. Several theories. Gestalt problem solving both productive and reproductive productive draws on insight and restructuring of problem attractive but not enough evidence to explain `insight' etc. move away from behaviourism and led towards information processing theories

68. Problem solving (cont.) Problem space theory problem space comprises problem states problem solving involves generating states using legal operators heuristics may be employed to select operators e.g. means-ends analysis operates within human information processing system e.g. STM limits etc. largely applied to problem solving in well-defined areas e.g. puzzles rather than knowledge intensive areas

69. Problem solving (cont.) Analogy analogical mapping: novel problems in new domain? use knowledge of similar problem from similar domain analogical mapping difficult if domains are semantically different Skill acquisition skilled activity characterized by chunking lot of information is chunked to optimize STM conceptual rather than superficial grouping of problems information is structured more effectively

70. Errors and mental models Types of error slips right intention, but failed to do it right causes: poor physical skill, inattention etc. change to aspect of skilled behaviour can cause slip mistakes wrong intention cause: incorrect understanding humans create mental models to explain behaviour. if wrong (different from actual system) errors can occur

71. Emotion Various theories of how emotion works James-Lange: emotion is our interpretation of a physiological response to a stimuli Cannon: emotion is a psychological response to a stimuli Schacter -Singer: emotion is the result of our evaluation of our physiological responses, in the light of the whole situation we are in Emotion clearly involves both cognitive and physical responses to stimuli

72. Emotion (cont.) The biological response to physical stimuli is called affect Affect influences how we respond to situations positive  creative problem solving negative  narrow thinking “Negative affect can make it harder to do even easy tasks; positive affect can make it easier to do difficult tasks” Implications for interface design stress will increase the difficulty of problem solving relaxed users will be more forgiving of shortcomings in design aesthetically pleasing and rewarding interfaces will increase positive affect

73. Individual differences long term – sex, physical and intellectual abilities short term – effect of stress or fatigue changing – age Ask yourself: will design decision exclude section of user population?

74. Semantic information map

75. Semantic information map

76. Computer: Text Entry Devices Typical Computer System various elements of a computer system that affects the interaction Input devices - text entry and pointing Output devices - screen (small & large), digital paper Virtual reality - special interaction and display devices Physical interaction - e.g. sound, haptic, bio-sensing Paper - as output (print) and input (scan) Memory - RAM & permanent media, capacity & access Processing - speed of processing, networks 2 1

77. Batch processing batch processing punched card stacks or large data files prepared long wait line printer output and if it is not right Now most computing is interactive rapid feedback the user in control (most of the time) doing rather than thinking

78. Pointing and Drawing Input devices for interactive use, allowing text entry, drawing and selection from the screen: Text entry: traditional keyboard, phone text entry, speech and handwriting Pointing: principally the mouse, but also touchpad, stylus, and others 3D interaction devices

79. Text Entry Devices keyboards (QWERTY et al.) Most common text input device Allows rapid entry of text by experienced users Keypress closes connection, causing a character code to be sent Usually connected by cable, but can be wireless Standardised layout non-alphanumeric keys are placed differently accented symbols needed for different scripts minor differences between UK and USA keyboards QWERTY QWERTY arrangement not optimal for typing – layout to prevent typewriters jamming! Alternative designs allow faster typing but large social base of QWERTY typists produces reluctance to change.

80. Alternative Keyboard Layouts Alphabetic keys arranged in alphabetic order not faster for trained typists not faster for beginners either! Dvorak common letters under dominant fingers biased towards right hand common combinations of letters alternate between hands 10-15% improvement in speed and reduction in fatigue But - large social base of QWERTY typists produce market pressures not to change

81. Special Keyboards designs to reduce fatigue for RSI for one handed use e.g. the Maltron left-handed keyboard

82. Chord keyboards only a few keys - four or 5 letters typed as combination of keypresses compact size ideal for portable applications short learning time keypresses reflect letter shape Fast once you have trained BUT - social resistance, plus fatigue after extended use NEW – niche market for some wearables

83. Phone Pad And T9 Entry use numeric keys with multiple presses 2 – a b c 6 - m n o 3 - d e f 7 - p q r s 4 - g h i 8 - t u v 5 - j k l 9 - w x y z hello = 4433555[ pause ]555666 surprisingly fast! T9 predictive entry type as if single key for each letter use dictionary to ‘guess’ the right word hello = 43556 … but 26 -> menu ‘am’ or ‘an’

84. Handwriting Recognition Text can be input into the computer, using a pen and a digesting tablet natural interaction Technical problems: capturing all useful information - stroke path, pressure, etc. in a natural manner segmenting joined up writing into individual letters interpreting individual letters coping with different styles of handwriting

85. Speech recognition Improving rapidly Most successful when: single user – initial training and learns peculiarities limited vocabulary systems Problems with external noise interfering imprecision of pronunciation large vocabularies different speakers

86. Positioning, Pointing And Drawing Mouse, Touchpad Trackballs, Joysticks Touch Screens Tablets Eyegaze , Cursors

87. The Mouse Handheld pointing device very common easy to use Two characteristics planar movement Buttons -(usually from 1 to 3 buttons on top, used for making a selection, indicating an option, or to initiate drawing etc.) Mouse located on desktop requires physical space no arm fatigue Relative movement only is detectable. Movement of mouse moves screen cursor Screen cursor oriented in (x, y) plane, mouse movement in (x, z) plane an indirect manipulation device. device itself doesn’t obscure screen, is accurate and fast. hand-eye coordination problems for novice users

88. Movement Detection Two methods for detecting motion Mechanical Ball on underside of mouse turns as mouse is moved Rotates orthogonal potentiometers Can be used on almost any flat surface Optical light emitting diode on underside of mouse may use special grid-like pad or just on desk less susceptible to dust and dirt detects fluctuating alterations in reflected light intensity to calculate relative motion in (x, z) plane some experiments with the footmouse controlling mouse movement with feet … not very common but foot controls are common elsewhere: car pedals sewing machine speed control organ and piano pedals

89. Touchpad small touch sensitive tablets ‘stroke’ to move mouse pointer used mainly in laptop computers good ‘acceleration’ settings important fast stroke lots of pixels per inch moved initial movement to the target slow stroke less pixels per inch for accurate positioning

90. Trackball and thumbwheels Trackball ball is rotated inside static housing like an upside down mouse! relative motion moves cursor indirect device, fairly accurate separate buttons for picking very fast for gaming used in some portable and notebook computers. Thumbwheels for accurate CAD – two dials for X-Y cursor position for fast scrolling – single dial on mouse

91. Joystick and keyboard nipple Joystick indirect pressure of stick = velocity of movement buttons for selection on top or on front like a trigger often used for computer games aircraft controls and 3D navigation Keyboard nipple for laptop computers miniature joystick in the middle of the keyboard

92. Touch-sensitive screen Detect the presence of finger or stylus on the screen. works by interrupting matrix of light beams, capacitance changes or ultrasonic reflections direct pointing device Advantages: fast, and requires no specialised pointer good for menu selection suitable for use in hostile environment: clean and safe from damage. Disadvantages: finger can mark screen imprecise (finger is a fairly blunt instrument!) difficult to select small regions or perform accurate drawing lifting arm can be tiring

93. Stylus and light pen Stylus small pen-like pointer to draw directly on screen may use touch sensitive surface or magnetic detection used in PDA, tablets PCs and drawing tables Light Pen now rarely used uses light from screen to detect location BOTH … very direct and obvious to use but can obscure screen

94. Digitizing tablet Mouse like-device with cross hairs used on special surface - rather like stylus very accurate - used for digitizing maps

95. Eyegaze control interface by eye gaze direction e.g. look at a menu item to select it uses laser beam reflected off retina … a very low power laser! mainly used for evaluation ( ch x) potential for hands-free control high accuracy requires headset cheaper and lower accuracy devices available sit under the screen like a small webcam

96. Cursor keys Four keys (up, down, left, right) on keyboard. Very, very cheap, but slow. Useful for not much more than basic motion for text-editing tasks. No standardised layout, but inverted “T”, most common

97. Discrete positioning controls in phones, TV controls etc. cursor pads or mini-joysticks discrete left-right, up-down mainly for menu selection

98. Display Devices Bitmap Screens (CRT & LCD) screen is vast number of coloured dots resolution and colour depth Resolution used (inconsistently) for number of pixels on screen (width x height) e.g. SVGA 1024 x 768, PDA perhaps 240x400 density of pixels (in pixels or dots per inch - dpi) typically between 72 and 96 dpi Aspect ratio ration between width and height 4:3 for most screens, 16:9 for wide-screen TV Colour depth : how many different colours for each pixel? black/white or greys only 256 from a pallete 8 bits each for red/green/blue = millions of colours

99. Anti-aliasing Jaggies diagonal lines that have discontinuities in due to horizontal raster scan process. Anti-aliasing softens edges by using shades of line colour also used for text

100. Cathode ray tube Stream of electrons emitted from electron gun, focused and directed by magnetic fields, hit phosphor-coated screen which glows used in TVs and computer monitors

101. Health hazards of CRT! X-rays: largely absorbed by screen (but not at rear!) UV- and IR-radiation from phosphors: insignificant levels Radio frequency emissions, plus ultrasound (~16kHz) Electrostatic field - leaks out through tube to user. Intensity dependant on distance and humidity. Can cause rashes. Electromagnetic fields (50Hz-0.5MHz). Create induction currents in conductive materials, including the human body. Two types of effects attributed to this: visual system - high incidence of cataracts in VDU operators, and concern over reproductive disorders (miscarriages and birth defects).

102. Liquid crystal displays Smaller, lighter, and … no radiation problems. Found on PDAs, portables and notebooks,and increasingly on desktop and even for home TV also used in dedicated displays: digital watches, mobile phones, HiFi controls How it works … Top plate transparent and polarised, bottom plate reflecting. Light passes through top plate and crystal, and reflects back to eye. Voltage applied to crystal changes polarisation and hence colour N.B. light reflected not emitted => less eye strain

103. Special displays Random Scan (Directed-beam refresh, vector display) draw the lines to be displayed directly no jaggies lines need to be constantly redrawn rarely used except in special instruments   Direct view storage tube (DVST) Similar to random scan but persistent => no flicker Can be incrementally updated but not selectively erased Used in analogue storage oscilloscopes

104. Large display used for meetings, lectures, etc. technology plasma – usually wide screen video walls – lots of small screens together projected RGB lights or LCD projector hand/body obscures screen may be solved by 2 projectors + clever software back-projected frosted glass + projector behind

105. Situated Displays displays in ‘public’ places large or small very public or for small group display only for information relevant to location or interactive use stylus, touch sensitive screen in all cases … the location matters meaning of information or interaction is related to the location

106. Hermes a situated display small displays beside office doors handwritten notes left using stylus office owner reads notes using web interface

107. Digital paper what? thin flexible sheets updated electronically but retain display how? small spheres turned or channels with coloured liquid and contrasting spheres rapidly developing area appearance cross section

108. virtual reality and 3D interaction positioning in 3D space moving and grasping seeing 3D (helmets and caves)

109. positioning in 3D space cockpit and virtual controls steering wheels, knobs and dials … just like real! the 3D mouse six-degrees of movement: x, y, z + roll, pitch, yaw data glove fibre optics used to detect finger position VR helmets detect head motion and possibly eye gaze whole body tracking accelerometers strapped to limbs or reflective dots and video processing

110. Pitch, Yaw and Roll yaw pitch roll

111. 3D displays desktop VR ordinary screen, mouse or keyboard control perspective and motion give 3D effect seeing in 3D use stereoscopic vision VR helmets screen plus shuttered specs, etc.

112. VR headsets small TV screen for each eye slightly different angles 3D effect

113. VR motion sickness time delay move head … lag … display moves conflict: head movement vs. eyes depth perception headset gives different stereo distance but all focused in same plane conflict: eye angle vs. focus conflicting cues => sickness helps motivate improvements in technology

114. simulators and VR caves scenes projected on walls realistic environment hydraulic rams! real controls other people

115. physical controls, sensors etc. special displays and gauges sound, touch, feel, smell physical controls environmental and bio-sensing

116. Dedicated Displays analogue representations: dials, gauges, lights, etc. digital displays: small LCD screens, LED lights, etc. head-up displays found in aircraft cockpits show most important controls depending on context

117. Sounds beeps, bongs, clonks, whistles and whirrs used for error indications confirmation of actions e.g. keyclick

118. Touch, feel, smell touch and feeling important in games … vibration, force feedback in simulation … feel of surgical instruments called haptic devices texture, smell, taste current technology very limited

119. BMW iDrive for controlling menus feel small ‘bumps’ for each item makes it easier to select options by feel uses haptic technology from Immersion Corp.

120. physical controls specialist controls needed … industrial controls, consumer products, etc. large buttons clear dials tiny buttons multi-function control easy-clean smooth buttons

121. Environment and bio-sensing sensors all around us car courtesy light – small switch on door ultrasound detectors – security, washbasins RFID security tags in shops temperature, weight, location … and even our own bodies … iris scanners, body temperature, heart rate, galvanic skin response, blink rate

122. paper: printing and scanning print technology fonts, page description, WYSIWYG scanning, OCR

123. Printing image made from small dots allows any character set or graphic to be printed, critical features: resolution size and spacing of the dots measured in dots per inch (dpi) speed usually measured in pages per minute cost!!

124. Types of dot-based printers dot-matrix printers use inked ribbon (like a typewriter line of pins that can strike the ribbon, dotting the paper. typical resolution 80-120 dpi ink-jet and bubble-jet printers tiny blobs of ink sent from print head to paper typically 300 dpi or better . laser printer like photocopier: dots of electrostatic charge deposited on drum, which picks up toner (black powder form of ink) rolled onto paper which is then fixed with heat typically 600 dpi or better.

125. Printing in the workplace shop tills dot matrix same print head used for several paper rolls may also print cheques thermal printers special heat-sensitive paper paper heated by pins makes a dot poor quality, but simple & low maintenance used in some fax machines

126. Fonts Font – the particular style of text Courier font Helvetica font Palatino font Times Roman font §´µº¿Â Ä¿~  (special symbol) Size of a font measured in points (1 pt about 1/72”) (vaguely) related to its height This is ten point Helvetica This is twelve point This is fourteen point This is eighteen point and this is twenty-four point

127. Fonts ( ctd ) Pitch fixed-pitch – every character has the same width e.g. Courier variable-pitched – some characters wider e.g. Times Roman – compare the ‘i’ and the “m” Serif or Sans-serif sans-serif – square-ended strokes e.g. Helvetica serif – with splayed ends (such as) e.g. Times Roman or Palatino

128. Readability of text lowercase easy to read shape of words UPPERCASE better for individual letters and non-words e.g. flight numbers: BA793 vs. ba793 serif fonts helps your eye on long lines of printed text but sans serif often better on screen

129. Page Description Languages Pages very complex different fonts, bitmaps, lines, digitised photos, etc. Can convert it all into a bitmap and send to the printer … but often huge ! Alternatively Use a page description language sends a description of the page can be sent, instructions for curves, lines, text in different styles, etc. like a programming language for printing! PostScript is the most common

130. Screen and page WYSIWYG what you see is what you get aim of word processing, etc. but … screen: 72 dpi, landscape image print: 600+ dpi, portrait can try to make them similar but never quite the same so … need different designs, graphics etc , for screen and print

131. Scanners Take paper and convert it into a bitmap Two sorts of scanner flat-bed: paper placed on a glass plate, whole page converted into bitmap hand-held: scanner passed over paper, digitising strip typically 3-4” wide Shines light at paper and note intensity of reflection colour or greyscale Typical resolutions from 600–2400 dpi Used in desktop publishing for incorporating photographs and other images document storage and retrieval systems, doing away with paper storage special scanners for slides and photographic negatives

132. Optical character recognition OCR converts bitmap back into text different fonts create problems for simple “template matching” algorithms more complex systems segment text, decompose it into lines and arcs, and decipher characters that way page format columns, pictures, headers and footers

133. Paper-based interaction paper usually regarded as output only can be input too – OCR, scanning, etc. Xerox PaperWorks glyphs – small patterns of /\\//\\\ used to identify forms etc. used with scanner and fax to control applications more recently papers micro printed - like watermarks identify which sheet and where you are special ‘pen’ can read locations know where they are writing

134. memory short term and long term speed, capacity, compression formats, access

135. Short-term Memory - RAM Random access memory (RAM) on silicon chips 100 nano -second access time usually volatile (lose information if power turned off) data transferred at around 100 Mbytes/sec Some non-volatile RAM used to store basic set-up information Typical desktop computers: 64 to 256 Mbytes RAM

136. Long-term Memory - disks magnetic disks floppy disks store around 1.4 Mbytes hard disks typically 40 Gbytes to 100s of Gbytes access time ~10ms, transfer rate 100kbytes/s optical disks use lasers to read and sometimes write more robust that magnetic media CD-ROM - same technology as home audio, ~ 600 Gbytes DVD - for AV applications, or very large files

137. Blurring boundaries PDAs often use RAM for their main memory Flash-Memory used in PDAs, cameras etc. silicon based but persistent plug-in USB devices for data transfer

138. speed and capacity what do the numbers mean? some sizes (all uncompressed) … this book, text only ~ 320,000 words, 2Mb the Bible ~ 4.5 Mbytes scanned page ~ 128 Mbytes (11x8 inches, 1200 dpi, 8bit greyscale) digital photo ~ 10 Mbytes (2–4 mega pixels, 24 bit colour) video ~ 10 Mbytes per second (512x512, 12 bit colour, 25 frames per sec)

139. Compression reduce amount of storage required lossless recover exact text or image – e.g. GIF, ZIP look for commonalities: text: AAAAAAAAAABBBBBCCCCCCCC 10A5B8C video: compare successive frames and store change lossy recover something like original – e.g. JPEG, MP3 exploit perception JPEG: lose rapid changes and some colour MP3: reduce accuracy of drowned out notes

140. Storage formats - text ASCII - 7-bit binary code for to each letter and character UTF-8 - 8-bit encoding of 16 bit character set RTF (rich text format) - text plus formatting and layout information SGML (standardized generalised markup language) - documents regarded as structured objects XML (extended markup language) - simpler version of SGML for web applications

141. Storage formats - media Images: many storage formats : (PostScript, GIFF, JPEG, TIFF, PICT, etc.) plus different compression techniques (to reduce their storage requirements) Audio/Video again lots of formats : (QuickTime, MPEG, WAV, etc.) compression even more important also ‘streaming’ formats for network delivery

142. methods of access large information store long time to search => use index what you index -> what you can access simple index needs exact match forgiving systems: Xerox “do what I mean” (DWIM) SOUNDEX – McCloud ~ MacCleod access without structure … free text indexing (all the words in a document) needs lots of space!!

143. Finite processing speed Designers tend to assume fast processors, and make interfaces more and more complicated But problems occur, because processing cannot keep up with all the tasks it needs to do cursor overshooting because system has buffered keypresses icon wars - user clicks on icon, nothing happens, clicks on another, then system responds and windows fly everywhere Also problems if system is too fast - e.g. help screens may scroll through text much too rapidly to be read

144. Moore’s law computers get faster and faster! 1965 … Gordon Moore, co-founder of Intel, noticed a pattern processor speed doubles every 18 months PC … 1987: 1.5 Mhz , 2002: 1.5 GHz similar pattern for memory but doubles every 12 months!! hard disk … 1991: 20Mbyte : 2002: 30 Gbyte baby born today record all sound and vision by 70 all life’s memories stored in a grain of dust!

145. The myth of the infinitely fast machine implicit assumption … no delays an infinitely fast machine what is good design for real machines? good example … the telephone : type keys too fast hear tones as numbers sent down the line actually an accident of implementation emulate in deisgn

146. Limitations on interactive performance Computation bound Computation takes ages, causing frustration for the user Storage channel bound Bottleneck in transference of data from disk to memory Graphics bound Common bottleneck: updating displays requires a lot of effort sometimes helped by adding a graphics co-processor optimised to take on the burden Network capacity Many computers networked shared resources and files, access to printers etc. but interactive performance can be reduced by slow network speed

147. Networked computing Networks allow access to … large memory and processing other people (groupware, email) shared resources – esp. the web Issues network delays – slow feedback conflicts - many people update data unpredictability

148. The internet history 1969: DARPANET US DoD, 4 sites 1971: 23; 1984: 1000; 1989: 10000 common language (protocols): TCP – Transmission Control protocol lower level, packets (like letters) between machines IP – Internet Protocol reliable channel (like phone call) between programs on machines email, HTTP, all build on top of these