human_factors_03.ppt

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  • op-Down and Bottom-Up Processing When an interpretation emerges from the data, this is called data-driven or bottom-up processing. Perception must be largely data-driven because it must accurately reflect events in the outside world. You want the interpretation of a scene to be determined mostly by information from the senses, not by your expectations. What is data-driven or bottom-up processing? What is schema-driven or top-down processing? In many situations, however, your knowledge or expectations will influence perception. This is called schema-driven or top-down processing. A schema is a pattern formed earlier in your experience. Larger scale or more abstract concepts are referred to as higher level, while concrete details (such as the input from the senses) are referred to as lower level. Top-down processing occurs any time a higher-level concept influences your interpretation of lower level sensory data. What is set or expectancy? Top-down processing is shown by the phenomena of set or expectancy. A classic example is the Rat Man of Bugelski and Alampay (1961).
  • human_factors_03.ppt

    1. 1. human-centered design <ul><li>Human factors within interactive digital media </li></ul><ul><li>Dr Nick Clarke </li></ul><ul><li>Lecturer in CAD for Fashion and Textiles </li></ul><ul><li>Fellow EADiM </li></ul><ul><li>School of Materials </li></ul><ul><li>Department of Textiles & Paper </li></ul><ul><li>Faculty of Engineering and Physical Sciences </li></ul><ul><li>School of Materials </li></ul><ul><li>University of Manchester </li></ul>
    2. 2. <ul><li>Focus on human commonalities - memory, perception and attention </li></ul><ul><li>Introduce the Information Processing Model of cognition </li></ul><ul><li>Suggest some human-centered design strategies derived from these understandings and the information processing model </li></ul>lecture: overview
    3. 3. guiding assumptions <ul><li>Human systems – memory, attention, perception – provide some unique constraints of which designers should be aware </li></ul><ul><li>Simple, common sense approaches to interface and information design can make a difference in using with online and offline multimedia environments </li></ul><ul><li>The more cognitive resources such as attention and memory that you can focus on the task (educational, navigational, instructional etc.), the better the ‘user’ outcomes (ie. learning). </li></ul><ul><li>HUMAN-CENTERED DESIGN MATTERS </li></ul>
    4. 4. human factors: memory systems
    5. 5. memory: sensory Memory system that supports momentary storage of large amounts of information gathered by our senses (echoic, iconic, haptic etc.) Data is stored in sensory registers for a brief period of time (under 5 sec.). This is enough time to either react or attend to critical information. Most data, however, is discarded.
    6. 6. memory: working Working memory provides a temporary workspace for information drawn from the sensory registers and activated from long term memory- it known as ‘STM’ ‘ STM’ is where ‘first’ thinking occurs. ‘ STM’ has a limited storage capacity for information. ‘ STM’ decays quickly without constant ‘memory rehearsal’.
    7. 7. memory: long-term Humans have a memory system that supports relatively permanent storage of information. It’s called ‘LTM’ - Long-Term Memory. Long-term memory has unlimited capacity.* Learning is about transferring information from working memory into long-term memory. Learning theories provide strategies for encoding information in a way that it can later be recalled and applied in situations we encounter.
    8. 8. sensory memory: processing <ul><li>Sensory memory facilitates feature analysis and pattern recognition which allows us to recognize family, friends and computer user interface elements </li></ul><ul><li>Recognition involves both ‘bottom-up processing’ and ‘top-down processing’ </li></ul><ul><ul><li>Perception is based upon bottom-up processing and helps us to distinguish between data elements. </li></ul></ul><ul><ul><li>Top-down processing provides interpretations of data. These are coloured by our understandings of specific contexts and environments. </li></ul></ul>
    9. 9. processes of perception <ul><li>The act of perception is a fast, but complex task </li></ul><ul><ul><li>break down complex stimuli into simple features </li></ul></ul><ul><ul><li>extract features from sensory data </li></ul></ul><ul><ul><li>construct patterns from this information </li></ul></ul><ul><ul><li>compare patterns with those in long-term memory </li></ul></ul><ul><ul><li>finding a match = perception </li></ul></ul>
    10. 10. sensory memory: processing & interpretation ex. jumping to conclusions
    11. 11. feature analysis: design implications use contrast and size to bring out salient features of letters and objects Ex. page background clearly delineated edges help feature analysis - line drawings and line-based icons are more quickly processed than tonal images leverage feature compatibility – are icons and fonts compatible with expectations? Ex. typography Icons and user interface elements should match a given interface context
    12. 12. <ul><li>Advantages: </li></ul><ul><ul><li>they are recognized as quickly as words </li></ul></ul><ul><ul><li>they support dual encoding </li></ul></ul><ul><ul><ul><li>as visual representations </li></ul></ul></ul><ul><ul><ul><li>and semantically </li></ul></ul></ul><ul><li>Disadvantages: </li></ul><ul><ul><li>difficult to develop universally recognised icons </li></ul></ul><ul><ul><li>difficult to develop a series of clear, distinct icons to represent different content and functionality </li></ul></ul>special issues: icons
    13. 13. rules of thumb: icons Use labels with icons. Icons should be distinct to aid memory. Clear, simple icons are often more easily interpreted than complex, 3-D tonal icons.
    14. 14. visual search & detection <ul><li>Understanding how humans search and detect visual information suggests strategies for interface and graphic design </li></ul><ul><ul><li>Humans use ‘Parallel’ and ‘Serial’ recognition. </li></ul></ul><ul><ul><li>Ex: Where's Wally? </li></ul></ul><ul><ul><li>There is strong evidence that Humans tend to search through elements on a screen in a serial fashion looking for a target. </li></ul></ul><ul><ul><li>Ex. Woodman, G.F, & Luck S.J. (1999) Research </li></ul></ul><ul><li>The time it takes to locate a target (the desired menu item, page content etc.) depends upon a few variables: </li></ul><ul><ul><li>The number of items on a screen – serial search; Neisser et al 1964. </li></ul></ul><ul><ul><li>Element conspicuity – parallel; things that stand out are located faster and elements noticed in parallel. </li></ul></ul><ul><ul><li>logical content organization and expectancies. </li></ul></ul>
    15. 15. visual search: design strategies
    16. 16. visual search: design strategies
    17. 17. working memory: model
    18. 18. working memory: capacity & duration <ul><li>hgniy </li></ul>
    19. 19. <ul><li>a f b z e g o y k t v p </li></ul>working memory: capacity & duration The Magic Number Seven – Plus or Minus Two - George Miller
    20. 20. working memory: capacity & duration <ul><li>b a t p i g d o g a n t </li></ul>
    21. 21. working memory: considerations <ul><li>The limits of working memory are an impediment to learning </li></ul><ul><ul><li>educational content </li></ul></ul><ul><ul><li>navigational structures </li></ul></ul><ul><ul><li>computer environments and interfaces </li></ul></ul><ul><li>Instructional and interface designs, content organization and site architecture should account for these limitations and potentials </li></ul>
    22. 22. focus on attention <ul><li>Information processing relative to learning requires a great degree of attention and cognitive resources </li></ul><ul><li>Like working memory, human attention is limited </li></ul><ul><li>Multitasking or splitting attention often causes a drop in performance of all tasks involved </li></ul><ul><li>If the majority of participants’ attention is consumed by the mechanics of your screen environment or wading through poor design and information structures, there will be less cognitive resources for the actual learning objectives </li></ul>
    23. 23. variables impacting attention <ul><li>Automaticity </li></ul><ul><ul><li>When a task becomes automatic it requires less in the way of conscious cognitive resources </li></ul></ul><ul><ul><li>Automaticity can increase our ability to multitask and attend to larger sets of information </li></ul></ul><ul><li>Multiple modalities </li></ul><ul><ul><li>It is easier to divide attention between two different modalities (one visual, one aural) than between two distinct information sources presented in the same modality </li></ul></ul><ul><ul><li>Earliest Memories </li></ul></ul>
    24. 24. working memory: design strategies <ul><li>Minimize the load on working memory for learning activities </li></ul><ul><ul><li>design user interfaces, interactive modules and learning materials so that participants are not required to hold large numbers of discreet chunks of information in memory ( remember the magic number 7 +/- 2 ). </li></ul></ul><ul><li>Organize information into meaningful chunks for working memory </li></ul><ul><ul><li>The limits of working memory can be extended when the chunks of information are larger. </li></ul></ul>
    25. 25. long-term memory: conceptual structures <ul><li>Information is organized into associative networks (schemas) </li></ul><ul><li>Schemas reflect central ideas or concepts </li></ul><ul><ul><li>Ex. What a web site is, a college campus etc. </li></ul></ul><ul><li>Scripts are schemas describing sequences of actions </li></ul><ul><ul><li>Ex. filling out & submitting a form on the web, navigating through a web site using hypertext links, driving a car to class, dining in a restaurant etc. </li></ul></ul><ul><li>Mental models are schemas of dynamic systems, objects & equipment </li></ul><ul><ul><li>Ex. VCRs, interactive web environments etc. </li></ul></ul>
    26. 26. long-term memory: design strategies <ul><li>If information is to be remembered, make it meaningful </li></ul><ul><ul><li>organize into meaningful associations. </li></ul></ul><ul><ul><li>present in multiple modes so that one can reinforce the other. </li></ul></ul><ul><ul><li>design in a manner consistent with existing mental models or pre-existing knowledge. </li></ul></ul><ul><ul><li>design information to highlight important connections and relationships. </li></ul></ul><ul><li>Embed knowledge in the world to support development of accurate mental models; use natural mappings </li></ul>
    27. 27. summary Human Factors implications <ul><li>Human systems – memory, attention, perception – provide unique design constraints of which designers should be aware </li></ul><ul><li>Simple, commonsensical approaches to interface and information design </li></ul><ul><ul><li>avoiding clutter </li></ul></ul><ul><ul><li>making things distinct and visible </li></ul></ul><ul><ul><li>reducing cognitive load from extraneous information </li></ul></ul><ul><ul><li>Designing interfaces to accommodate human expectations of the web </li></ul></ul><ul><li>can make a difference in learning from web-based environments </li></ul><ul><li>The more cognitive resources (attention, memory etc.) that you can focus on the educational task, the better the outcomes – </li></ul><ul><li>HUMAN-CENTERED DESIGN MATTERS </li></ul>
    28. 28. human-centered principles & interface design <ul><li>Interface </li></ul><ul><ul><li>Mediator between a user and the underlying system or environment. </li></ul></ul><ul><ul><li>Can either facilitate or inhibit use depending upon how well they incorporate human-centered principles. </li></ul></ul>
    29. 29. design heuristics Jakob Nielsen <ul><li>10 Design Heuristics </li></ul><ul><ul><li>Visibility of system status </li></ul></ul><ul><ul><li>Match between system and real world </li></ul></ul><ul><ul><li>User control and freedom </li></ul></ul><ul><ul><li>Consistency and standards </li></ul></ul><ul><ul><li>Error prevention </li></ul></ul><ul><ul><li>Recognition rather than recall </li></ul></ul><ul><ul><li>Flexibility and efficiency of use </li></ul></ul><ul><ul><li>Aesthetic and minimalist design </li></ul></ul><ul><ul><li>Help users recognize, diagnose and recover from errors </li></ul></ul><ul><ul><li>Help and documentation </li></ul></ul>
    30. 30. design heuristics: visibility of system status The system should always keep users informed about what is going on, through appropriate feedback within reasonable time.
    31. 31. design heuristics: system = real world The system should speak the users' language, with words, phrases and concepts familiar to the user, rather than system-oriented terms. Follow real-world conventions, making information appear in a natural and logical order. .
    32. 32. design heuristics: visibility of system status
    33. 33. design heuristics: control & freedom Users often choose system functions by mistake and will need a clearly marked &quot;emergency exit&quot; to leave the unwanted state without having to go through an extended dialogue. Support undo and redo.
    34. 34. design heuristics: control & freedom Users often choose system functions by mistake and will need a clearly marked &quot;emergency exit&quot; to leave the unwanted state without having to go through an extended dialogue. Support undo and redo.
    35. 35. design heuristics: consistency & standards Users should not have to wonder whether different words, situations, or actions mean the same thing. Follow platform conventions.
    36. 36. design heuristics: consistency & standards Users should not have to wonder whether different words, situations, or actions mean the same thing. Follow platform conventions.
    37. 37. design heuristics: error prevention Even better than good error messages is a careful design which prevents a problem from occurring in the first place. Either eliminate error-prone conditions or check for them and present users with a confirmation option before they commit to the action.
    38. 38. design heuristics: recognition & recall Minimize the user's memory load by making objects, actions, and options visible. The user should not have to remember information from one part of the dialogue to another. Instructions for use of the system should be visible or easily retrievable whenever appropriate.
    39. 39. design heuristics: recognition & recall Minimize the user's memory load by making objects, actions, and options visible. The user should not have to remember information from one part of the dialogue to another. Instructions for use of the system should be visible or easily retrievable whenever appropriate.
    40. 40. design heuristics: recognition & recall Minimize the user's memory load by making objects, actions, and options visible. The user should not have to remember information from one part of the dialogue to another. Instructions for use of the system should be visible or easily retrievable whenever appropriate.
    41. 41. design heuristics: flexibility & efficiency of use Accelerators -- unseen by the novice user -- may often speed up the interaction for the expert user such that the system can cater to both inexperienced and experienced users. Allow users to tailor frequent actions.
    42. 42. design heuristics: flexibility & efficiency of use Accelerators -- unseen by the novice user -- may often speed up the interaction for the expert user such that the system can cater to both inexperienced and experienced users. Allow users to tailor frequent actions.
    43. 43. design heuristics: aesthetic & minimalist design Dialogues should not contain information which is irrelevant or rarely needed. Every extra unit of information in a dialogue competes with the relevant units of information and diminishes their relative visibility.
    44. 44. design heuristics: aesthetic & minimalist design Dialogues should not contain information which is irrelevant or rarely needed. Every extra unit of information in a dialogue competes with the relevant units of information and diminishes their relative visibility.
    45. 45. design heuristics: aesthetic & minimalist design Dialogues should not contain information which is irrelevant or rarely needed. Every extra unit of information in a dialogue competes with the relevant units of information and diminishes their relative visibility.
    46. 46. design heuristics: aesthetic & minimalist design Dialogues should not contain information which is irrelevant or rarely needed. Every extra unit of information in a dialogue competes with the relevant units of information and diminishes their relative visibility.
    47. 47. design heuristics: aesthetic & minimalist design Dialogues should not contain information which is irrelevant or rarely needed. Every extra unit of information in a dialogue competes with the relevant units of information and diminishes their relative visibility.
    48. 48. design heuristics: recognise, diagnose and recover errors Error messages should be expressed in plain language (no codes), precisely indicate the problem, and constructively suggest a solution.
    49. 49. design heuristics: recognise, diagnose and recover errors Error messages should be expressed in plain language (no codes), precisely indicate the problem, and constructively suggest a solution.
    50. 50. design heuristics: help & documentation Even though it is better if the system can be used without documentation, it may be necessary to provide help and documentation. Any such information should be easy to search, focused on the user's task, list concrete steps to be carried out, and not be too large.
    51. 51. [email_address] <ul><li>FIN </li></ul>
    52. 52. visual search & detection Serial and Parallel Searching

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