ITM 734 Introduction to Human Factors in Information Systems

1. ITM 734Introduction to Human Factors in Information Systems Human Abilities: Cognitive Abilities Cindy Corritore cindycc@gmail.com This material has been developed by Georgia Tech HCI faculty, and continues to evolve.

2. Basic Human Capabilities • Do not change very rapidly • Not like Moore’s law! • Have limits, which are important to understand • Our understanding of human capabilities does change, ie • Cognitive neuroscience • Theories of color perception • Effect of groups and situation on how we act and react ITM 734 (Corritore)

3. The “Model Human Processor” • A true classic - see Card, Moran and Newell, The Psychology of Human-Computer Interaction, Erlbaum, 1983 • Microprocessor–human analog using results from experimental psychology • Provides a view of the human that fits much experimental data ITM 734 (Corritore)

4. Block Diagram - Model Human Processor (MHP) LONG-TERM MEMORY SHORT-TERM (WORKING) MEMORY VISUAL IMAGE STORE AUDITORY IMAGE STORE PERCEPTUAL PROCESSOR COGNITIVE PROCESSOR MOTOR PROCESSOR ITM 734 (Corritore)

5. MHP is not Complete • Only two senses • Certainly the most important • Focus is on a single user interacting with some entity (computer, environment, tool) • Neglects effect of other people ITM 734 (Corritore)

6. Three Processors • Perceptual Processor • Cognitive Processor • Motor Processor • Each has a cycle time (average and range), determined experimentally • Represented by C ITM 734 (Corritore)

7. Block Diagram - MHP – Three Processors, Cycle Times LONG-TERM MEMORY SHORT-TERM (WORKING) MEMORY VISUAL IMAGE STORE AUDITORY IMAGE STORE PERCEPTUAL PROCESSOR C = 100 [5-200] ms COGNITIVE PROCESSOR C = 70 [27-170] ms MOTOR PROCESSOR C = 70 [30-100] MS C = Cycle Time [Range] Eye movement (Saccade) = 230 [70-700] ms ITM 734 (Corritore)

8. Through all of this …. • limited cognitive resources/load (memory load) • analogy • flawed plans (heuristics) • simulations (cognitive/mental models) • goal – to minimize complexity through improved fit (between user, computer, and task) ITM 734 (Corritore)

9. Block Diagram – MHP – Three Memories LONG-TERM MEMORY Memory 3 - permanent memory, hugh capacity SHORT-TERM (WORKING) MEMORY VISUAL IMAGE STORE AUDITORY IMAGE STORE Memory 2 - working memory, small capacity, conscious thought, calculations PERCEPTUAL PROCESSOR COGNITIVE PROCESSOR MOTOR PROCESSOR Memory 1 - Perceptual Buffers to briefly store impressions ITM 734 (Corritore)

10. Block Diagram – MHP – Three Memories, Rep’n, Decay Time, Size LONG-TERM MEMORY R = Semantic + Visual + Auditory D = Infinite S = Infinite SHORT-TERM (WORKING) MEMORY VISUAL IMAGE STORE AUDITORY IMAGE STORE R= Acoustic or Visual D (1 chunk) = 73 [73-226] s D (3 chunks) = 7 [5-34] s S = 7 [5-9] chunks R = Visual D = 200 [70-1000] ms S = 17 [7-17] letters R = Acoustic D = 1.5 [0.9-3.5] s S = 5 [4.4-6.2] letters PERCEPTUAL PROCESSOR C = 100 [5-200] ms COGNITIVE PROCESSOR C = 70 [27-170] ms MOTOR PROCESSOR C = 70 [30-100] MS R = Representation D = Decay Time S = Size C = Cycle Time [Range] Eye movement (Saccade) = 230 [70-700] ms ITM 734 (Corritore)

11. Memory 1 – Perceptual Stores (sensory memory) • Memory structures • Image Stores - Holds fixed image of outside world long enough for some analysis • Processes - Info goes to brain for more processing • e.g. Pattern recognition • Uses context & knowledge to make sense of what is seen/heard ITM 734 (Corritore)

12. Perceptual Stores • Visual and auditory impressions • Visuospatial sketchpad, phonological loop • Very brief, but accurate representation of what was perceived • Details decay quickly (70 - 1000 ms visual; 0.9 - 3.5 sec auditory) • Limited capacity (7 - 17 letters visual; 4 - 6 auditory) ITM 734 (Corritore)

13. Perceptual stores • buffers for incoming data via senses • different one for each sense • short-lived and space-constrained • persistence (fireworks in vision after the fact) • some processing even if not attended • attention brings it into STM • cocktail party phenomenae ITM 734 (Corritore)

14. Memory 2 – Short Term Memory STM • Representation is either auditory or visual • Rehearsal needed to prevent decay (try it) • Without rehearsal, decays in minute or less • Can store as long as are able to pay attention to rehearsal – harder than you think (try it) • Another task prevents rehearsal - interference • New info can “push out” old info - interference • Capacity is 5 to 9 “chunks” of information ITM 734 (Corritore)

15. About Chunks • A chunk is a meaningful grouping of information – allows assistance from LTM • 4793619049 vs. 404 894 7328 • NSAFBICIANASA vs. NSA FBI CIA NASA • My chunk may not be your chunk • User and task dependent ITM 734 (Corritore)

16. STM • gateway to sensory and LTM? • no – conversation goes directly to LTM • role of rehearsal exaggerated (moving from STM to LTM) • lots in LTM that is not rehearsed (eg. snapshot of a birthday celebration) ITM 734 (Corritore)

17. STM characteristics • recency - last few items in list recalled better than middle - holding most recent items in STM • negate with interference? • visual and auditory channel - no interference if different channel • primacy - first few items in list recalled better than middle (more rehearsal) ITM 734 (Corritore)

18. STM characteristics • quick access and quick decay (volatile) • limited in size • chunking (experts vs. novices) - phone number • 402-111-5555 • forgetting • time decay? • interference with new items? (eg. similarity) • attention moves off item? ITM 734 (Corritore)

19. Memory 3 – Long-Term Memory LTM • Seemingly permanent & unlimited • Slow but variable access speed • Access is harder, slower • -> Activity helps (we have a cache) • Representations are semantic (declarative, procedural) and visual and auditory • Facts, procedures, pictures, sounds • Retrieval depends on network of semantic associations (“linked lists”) File system full ITM 734 (Corritore)

20. LTM characteristics • Retrieval depends on …. • recency • expectations • similarity of information • connectedness • rehearsal • richness & nature of processing at learning • level or depth or processing (shallow vs deep perceptual analysis) • distinctiveness of processing • amount of processing • elaborate far better ITM 734 (Corritore)

21. Richness • paragraph – listen and remember ….. ITM 734 (Corritore)

22. Types of LTM • Explicit and Implicit • conscious recollection, top-down retrieval from multiple systems with massive integration (E) • unconscious recollection, bottom-up from single system (I) – more automatic ITM 734 (Corritore)

23. Types of LTM • Episodic and Semantic • episodic: self-awareness component, things that happen to you, complex (E) • semantic: stuff we know, knowledge about the world, relationships, implicit - dictionary, thesaurus • likely stored the same way ITM 734 (Corritore)

24. Types of LTM • Declarative and Procedural • knowing that, explicit primarily, relationships, integration of information (D) – knowing things and their relationships • knowing how, mostly implicit, not relational – how to do things ITM 734 (Corritore)

25. Memory structures for stories, events … • Schema - framework that includes frames & scripts • become chunks for expanding memory • basis for expectations • Bartlett’s Schema Theory • framework for stories that affects comprehension • told American Indian stories, then recall - • readjusted story elements and themes to fit their model • Chunking in experts • Helps make it easier to recall, group information • Experts have great, robust schema and chunks ITM 734 (Corritore)

26. LTM processes • Storage • rehearsal • Retrieval • Forgetting • Recognition vs recall • Frequency and recency effects ITM 734 (Corritore)

27. Storage- Rehearsal • Memorization involves storing the information and one or more access paths • Good memories are rich semantic networks with many (unique) access paths • Learning is aided by meaningfulness, structure, familiarity and concreteness • Active memorizing requires effort, motivation • Passive memorizing - unpredictable, often episodic, context sensitive • Similar items interfere if they are not separated during memorizing - learning transfer effects - old interfere with new; new overwrite old ITM 734 (Corritore)

28. Facilitating Memorization • Structure information to help chunking - use categories, ordering, associations • Encourage reasoning during memorizing - active memory • Help access by multiple pathways - memorizing tricks e.g. keywords, cognitive aids, mnemonics, link to image memory (rooms) • Make associations clear and keep them consistent ITM 734 (Corritore)

29. Facilitating Memorization • Make separate and recognizable contexts for recall - important for script / skill memory • Increase depth of encoding • Richness • Visualization • sorting - http://www.cs.ubc.ca/spider/harrison/Java/sorting-demo.html • Uniqueness • Interaction • Recognition vs Recall ITM 734 (Corritore)

30. Facilitating Memorization: Mnemonics • cognitive mnemonics • ABC’s with tune • on old olympus mountain tops a finn and german viewed some hops (12 crainial nerves: OOOMTAFAGVSH) • seems to be more to remember? ITM 734 (Corritore)

31. Facilitating Memorization: Mnemonics • check out: http://human-factors.arc.nasa.gov/cognition/tutorials/index.html • mnemonic for Norman principles: visibility, feedback, cognitive/conceptual model, affordance, mapping My Fat Cat Ate Veggies ITM 734 (Corritore)

32. Recall vs. recognition • Knowledge in the World Theory is GUI’s - Alan Kay developed in 1960’s • Steve Jobs in late 1970’s from Xerox Parc • keep knowledge in world to supplement head knowledge • recall vs. recognition • remember just enough detail to get by • exceptions rather then norms • experts not expert in knowledge in the head as much as expert in how to locate needed knowledge in the world (Norman Ch 2) ITM 734 (Corritore)

33. Design implications • Reduce cognitive load!!! ITM 734 (Corritore)

34. Design implications • Mental models natural extensions of schema - support schemas • metaphors - desktop/office • match system information structure with familiar memory structures so user can use their schema ITM 734 (Corritore)

35. Design implications • Design interfaces that help users ‘grow’ good mental models • meaningful and familiar command names (eg. from task world) • balance this with existing conceptual models of item names (ie. cut, copy) • Incorporate closure (finish) on tasks • helps build mental model • helps identify chunks for memory when become an expert • Consistency - to build mental model; don’t have to remember as much ITM 734 (Corritore)

36. Design implications • Rich encoding - • multimedia • interaction • context? • May just be to ‘remember your site’ or help with visualization • http://www.jordans.com/roomplanner.asp • http://www.smartmoney.com/marketmap/ • http://www.sitepal.com/?source=gawweb06&kw=talking+website&creative=581895729 ITM 734 (Corritore)

37. Design implications • Focus on recognition rather than recall • interface contains prompts/information • studies on computer experts found they don’t have better recall, but high recognition of what is and isn’t available on interface and where to find it (mental maps) • GUI’s combination of recognition (menu’s) and recall (quick keys) ITM 734 (Corritore)

38. Design implications • Place the burden of remembering on the machine, not the human • Don’t require user memory (eg. between screens) • Don’t have computer ask for info it can derive ITM 734 (Corritore)

39. Design implications • Design minor messages, alerts, warning to be minimally disruptive • prevent user from forgetting data stored in short term memory ITM 734 (Corritore)

40. Attention • Humans can focus mental resources on a single event/object • helps to simplify environmental input (filter) • works with perception - perceive what attending to • can divide attention (multiprocessing, not parallel) • problem - distraction on second task, don’t return to first task in right place. • often use world reminders to hold place in first task (post-it note) ITM 734 (Corritore)

41. Attention • examples • driving a car -must attend to some stimuli, ignore others • listening to this lecture - attend to slides and words, ignore other students, physical plant noises ITM 734 (Corritore)

42. Divided attention • doing two things at once • affected by • task similarity – similar how? • practice (experience) - automaticity • task difficulty – require more resources than are available? • what happens: interference ITM 734 (Corritore)

43. Success in time sharing attention • four mechanisms account for how well we divide our attention 1. automaticity and resources 2. resource allocation and switching 3. structural factors 4. confusion and similarity ITM 734 (Corritore)

44. 1. automaticity and resources • Automatic vs. Controlled : perform task without thinking about it or require attention, conscious control. Happens over time. Controlled – do something directed by thought. • Automatic: • good as fast, doesn’t interfere with other tasks (need minimal attention), unconscious • bad - unavailable to conscious level, hard to change (driving a shift), can interfere with other automatic processes, harder to unlearn www.apa.org/science/stroop.html) ITM 734 (Corritore)

45. automaticity • Stroup effect – read the words on next page outloud as fast as you can … ITM 734 (Corritore)

46. Mismatch • Stroop effect: name the colour: RED GREEN BLUE YELLOW BROWN PURPLE • Color has not been shown empirically to be superior ITM 734 (Corritore)

47. 1. automaticity and resources • automatic processing can time-share efficiently • doesn't require a lot of cognitive resources • eg. walking • factor: effort and difficulty of additional tasks • if task difficult, requires more resources • if have dual tasks, performance will decrease since resources are being shared • automatic tends to reduce the difficulty ITM 734 (Corritore)

48. 1. automaticity and resources • can only increase performance so much • level equal to ‘full’ resource use on a task, performance data limited (no further benefit from adding more resources) • perfect example: no matter how hard I try (invest resources & effort), I won't improve my understanding of a discussion in French beyond a rudimentary level. • also called resource-limited ITM 734 (Corritore)

49. 1. automaticity and resources • bottom line • increase effort into a task, improve performance to point if resource limited • increase difficulty of task decreases performance unless add resources • in dual tasks, if increase resources for one task, will decrease resources for second task and subsequent performance • depends on automaticity ITM 734 (Corritore)

50. 2. resource allocation and switching • result of two + tasks co-occuring • now look at how you can allocate and switch attention between tasks • we don't have elaborate schemes to optimize resource allocation • can improve time sharing with these strategies • totally depends on the individual • can train how to control attention ITM 734 (Corritore)