1. AVI/Psych 358/IE 340: Human Factors Cognition September 12-17 2008

2. 2 Admin HW 1 (Due next Friday) Re-organized groups (check your groups)

3. 3 Overview What is cognition? What are users good and bad at? Describe how cognition has been applied to interaction design Theories of cognition –Mental models –Theory of action, evaluation (action cycle)

4. 4 Cognition: What goes on in the mind?

5. 5 Why do we need to understand users? Interaction requires cognition –Need to understand cognitive abilities and limitations of users –Provide support in situations of cognitive limitations Develop better interactive products by understanding cognitive processes of users

6. 6 Core cognitive aspects Attention Perception and recognition Memory Reading, speaking and listening Problem-solving, planning, reasoning and decision-making, learning Most relevant to interaction design are attention, perception and recognition, and memory

7. 7 Attention Selecting things to concentrate on at a point in time from the mass of stimuli around us Allows us to focus on information that is relevant to what we are doing

8. 8 Attention Could involve audio and/or visual senses Examples of interface components to support human attention: color, boundaries, flashing, grouping (e.g. drop down menus)

9. 9 Activity: Find the price of a double room at the Holiday Inn in Bradley

10. 10 Activity: Find the price for a double room at the Quality Inn in Columbia

11. 11 What catches your eye?

12. 12 London Underground RR

13. 13 Design guidelines for attention Make information salient when it needs attending to Use techniques that make things stand out like color, ordering, spacing, underlining, sequencing and animation Avoid cluttering the interface - follow the google.com example of crisp, simple design

14. 14 What attention design guidelines are implemented on Google?

15. 15 Perception and recognition How information is acquired from the world via the different sense organs (vision, sound, touch etc)

16. 16 Perception and recognition Obvious implication is to design representations that are readily perceivable, e.g. –Structuring information –Text should be legible –Icons should be easy to distinguish and understand

17. 17 Which is easiest to read and why? What is the time?

18. 18 flom vask dute froo nite geng cruke heem aremp racan stoff lonnup meby tane niddo

19. 19 yellow purple blue red green purple green red blue purple brown blue orange red green

20. 20 Design Guidelines Representations of information need to be designed to be perceptible and recognizable –E.g. clearly delineated boundaries, color etc Icons and graphical representations to enable users to readily distinguish their meaning

21. 21 Design Guidelines Bordering and spacing to effectively group information Use of sounds Text should be legible and distinguishable from the background

22. 22 Perception Constructing meaning through perception Organizing visual sensory data Grouping units together (perception of rows, columns, figures, relationships etc) Design goal: support the perceptual process –Layout and organization, avoid ambiguity

23. 23 Ambiguity in Perception

24. 24 Gestalt Principles proximity similarity symmetry continuity closure a c d b

25. 25 Examples from UI ProximitySimilarity Closure Symmetry Continuity

26. 26 Examples from UI (Cont’d)

27. 27 Computer Vendor Activity Analyze www.apple.com and www.dell.com with respect to their perceptual aspects: (1) gestalt, (2) virtual affordances and (3) other perceptual elementswww.apple.comwww.dell.com ProximitySimilarity Closure Symmetry Continuity

28. 28 Memory Involves first encoding and then retrieving knowledge We don’t remember everything - involves filtering and processing what is attended to

29. 29 Memory Context is important in affecting our memory (i.e., where, when) Well known fact that we recognize things much better than being able to recall things –Better at remembering images than words –Why interfaces are largely visual

30. 30 Processing in memory Encoding is first stage of memory –determines which information is attended to in the environment and how it is interpreted Higher the attention paid to something, better the recall

31. 31 Processing in memory And the more it is processed in terms of thinking about it and comparing it with other knowledge Repetition is another way of reinforcing memory (e.g. repeated use of a software system)

32. 32 Miller’s theory George Miller’s theory of how much information people can remember People’s immediate memory capacity is very limited Many designers have been led to believe that this is useful finding

33. 33 Magic Number‘7  2’ People can remember 7+/- 2 ‘chunks’ of information For example: read a list of numbers and try to repeat it without looking at them ‘Chunks’ – are logical combinations that can be derived (e.g. related words – microwave oven; referee-umpire)

34. 34 What some designers get up to… Present only 7 options on a menu Display only 7 icons on a tool bar Have no more than 7 bullets in a list Place only 7 items on a pull down menu Place only 7 tabs on the top of a website page –But this is wrong? Why?

35. 35 Why? Inappropriate application of the theory People can scan lists of bullets, tabs, menu items till they see the one they want They don’t have to recall them from memory having only briefly heard or seen them

36. 36 Recap

37. 37 Cognition Perception – forming consciousness Working memory – temporal storage Long-term memory – information retrieval

38. 38 Attention Attention Resources, a pool of attention or mental effort –Limited availability –Can be allocated to processes as required

39. 39 Selective Attention-Salience Attentional capture –Captures attention automatically –Distinct color –Unique rhythm –Sudden vibration –Abrupt onset of a flash

40. 40 HF guidelines in Perception Maximize bottom-up processing –Legibility, contrast, bigger fonts, etc. Maximize automaticity and unitization –Familiar perceptual representations Maximize top-down processing –Past experiences –Associations, e.g. green for go, red for no-go

41. 41 Working memory Is limited 7 ± 2 Chunking

42. 42 HF guidelines in Working memory Minimize working memory load Exploit chunking Minimize confusability Consider working memory limits in instructions

43. 43 Long term memory Storing information and retrieving it at later times Semantic memory – facts or procedures Event memory – specific events

44. 44 Long term memory Frequency and recency of its use –A password used everyday vs. occasionally –A newly learned skill used the next day or 3 months later Association –How one item may be linked with other items

45. 45 Long term memory - Forgetting Why do we forget things? –Weak strength due to low frequency or recency –Weak associations –Interfering associations Learning & Training Recall vs. recognition

46. 46 Long term memory – Implications for design Increase frequency and recency Standardize controls, displays, symbols, operating procedures, etc. Use memory aids Add meaningfulness Support mental model