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humancomputer interaction lecture number 2.pdf
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- 2. Content The human The computer The interaction
- 3. Beginnings- Computing in1945 Harvard Mark I ASCC: IBM Automatic Sequence Controlled Calculator (aka Mark 1) 55 feet long, 8 feet high, 5 tons
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- 8. What Interactions didwe See Mechanical Poor feedback Specialist use Process control Calculations No intention to address the mass market
- 9. Development of HCI Early computers: Extremely difficult to use Large and Expensive By comparison: “people time” (labour) cheap Used by specialists No knowledge about how to make use easier
- 10. Development of HCI Early computers: Extremely difficult to use Large and Expensive By comparison: “people time” (labour) cheap Used by specialists No knowledge about how to make use easier Today None of these conditions hold Development of PC’s major landmark
- 11. Development of HCI Early computers: extremely difficult to use Large and Expensive By comparison: “people time” (labour) cheap Used by specialists No knowledge about how to make use easier Today None of these conditions hold Development of PC’s major landmark Shift to other interaction paradigms Small-handheld-Devices Mobility
- 12. What is HCI HCI is the study of interaction between human (users) and computers. The interaction between user(s) and computer(s) is achieved via an interface – user interface
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- 16. Principle of HCI(Usability) useful Accomplish what is required (functional, does things) usable Do it easily and naturally without error (does the right things) used Make people want to use it (be attractive, acceptable to organization)
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- 18. The human Vision Hearing Touch Movement
- 19. Why do weneed to understand Humans in HCI Humans are limited in their capacity to process information. This has important implications for design Interacting with technology is cognitive Human Information Processing is referred to as cognition
- 20. Optical Illusions “Theseillusion demonstrate that our perception of size is not completely reliable” the Ponzo illusion the Muller Lyer illusion
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- 22. What is humanmemory? It is the ability to store and retrieve the information Much of our everyday activity relies on memory We need to understand some of the capabilities and limitations of human memory to answer these How does memory works? How do we remember some arbitrary list ? Why do some people remember more easily than others?
- 23. Memory There are threetypes of memory function: Sensory memories Short-term memory or working memory Long-term memory Selection of stimuli governed by level of arousal.
- 24. Human memory Humanmemory has limited capacity- 7± 2 chunks There are two methods for measuring memory capacity Recall the sequence in order Recall the sequence in any order
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- 27. Try this! 212348278493202 01 21414 2626
- 28. Human memory Patternscan be useful as aids to memory
- 29. Try this! Patternscan be useful as aids to memory HEC ATR ANU PTH ETR EET
- 30. Try this! Patternscan be useful as aids to memory HEC ATR ANU PTH ETR EET The sequence is easy to recall (the cat ran up the tree)
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- 32. The Computer a computersystem is made up of various elements each of these elements 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
- 33. A ‘typical’ computersystem keyboard mouse/trackpad screen, or monitor, on which there are windows variations desktop laptop PDA the devices dictate the styles of interaction that the system supports If we use different devices, then the interface will support a different style of interaction window 1 window 2 12-37pm ?
- 34. Keyboards Most commontext 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
- 35. Layout – QWERTY Standardised layout but … non-alphanumeric keys are placed differently accented symbols needed for different scripts minor differences between UK and USA keyboards 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.
- 36. QWERTY (ctd) 2 34 5 6 7 8 9 0 Q W E R T Y U I 1 O P S D F H J L A G K Z X C V B N M , . SPACE
- 37. 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
- 38. Chord keyboards only afew 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
- 39. Special keyboards designsto reduce fatigue for RSI (repetitive strain injury) for one handed use e.g. the Maltron left-handed keyboard
- 40. Numeric keypads: twodifferent style for entering numbers quickly: calculator, PC keyboard for telephones not the same!! ATM like phone 4 5 6 7 8 9 * 0 # 1 2 3 4 5 6 1 2 3 0 . = 7 8 9 Telephone style Calculator style
- 41. The Mouse Handheldpointing 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.)
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- 43. Touchpad small touchsensitive 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
- 44. Trackball and thumbwheels Trackball ball is rotated inside static housing like an upsdie down mouse! 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
- 45. Joystick Joystick indirect pressure ofstick = velocity of movement buttons for selection on top or on front like a trigger often used for computer games aircraft controls and 3D navigation
- 46. 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 no n-vo latile RA Mused to store basic set-up information Typical desktop computers: 64 to 256 Mbytes RAM
- 47. 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
- 48. 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 pe r se co nd (512x512, 12 bit colour, 25 frames per sec)
- 49. 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 electron gun focussing and deflection electron beam phosphor- coated screen
- 50. 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 dedicted 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
- 51. Printing image madefrom 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!!
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- 53. Interaction Paradigms BatchProcessing Timesharing Networking (1972 1st email) Graphical display Microprocessor WWW Grid/Clouds Computing Human Robot Interaction Tablet/Table Top Computing 1950’s 1960’s 1970’s 1980’s 1990’s 1995’s This era …
- 54. Types of userinterfaces (Common interaction styles) Command line interface Menus Natural language Question/answer and query dialogue Form-fills and spreadsheets WIMP Point and click Three–dimensional interfaces
- 55. Command line interface Way of expressing instructions to the computer directly function keys, single characters, short abbreviations, whole words, or a combination suitable for repetitive tasks better for expert users than novices offers direct access to system functionality command names/abbreviations should be meaningful! Typical example: the Unix system
- 56. Menus Set ofoptions displayed on the screen Options visible less recall - easier to use rely on recognition so names should be meaningful Selection by: numbers, letters, arrow keys, mouse combination (e.g. mouse plus accelerators) Often (frequent) options hierarchically grouped sensible grouping is needed Restricted form of full WIMP system
- 57. Natural language Familiarto user speech recognition or typed natural language Problems vague ambiguous hard to do well! Solutions try to understand a subset pick on key words
- 58. Query interfaces Question/answerinterfaces user led through interaction via series of questions suitable for novice users but restricted functionality often used in information systems Query languages (e.g. SQL) used to retrieve information from database requires understanding of database structure and language syntax, hence requires some expertise
- 59. Form-fills Primarily fordata entry or data retrieval Screen like paper form. Data put in relevant place Requires good design obvious correction facilities
- 60. Spreadsheets First spreadsheetVISICALC, followed by Lotus 1-2-3 MS Excel most common today Sophisticated variation of form-filling. grid of cells contain a value or a formula formula can involve values of other cells e.g. sum of all cells in this column user can enter and alter data spreadsheet maintains consistency
- 61. WIMP Interface Windows Icons Menus Pointers … orwindows, icons, mice, and pull-down menus! default style for majority of interactive computer systems, especially PCs and desktop machines
- 62. Point and clickinterfaces used in .. multimedia web browsers hypertext just click something! icons, text links or location on map minimal typing
- 63. Three dimensional interfaces virtual reality ‘ordinary’ window systems highlighting visual affordance indiscriminate use just confusing! 3D workspaces use for extra virtual space light and occlusion give depth distance effects flat buttons … … or sculptured click me!
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