Cognitive Issues & Human Tasks

1. Cognitive Issues & Human Tasks CS 7450 - Information Visualization January 18, 2005 John Stasko

2. Outline • Overview • 1. Role – How visualizations aid cognition? • 2. Tasks – What does the visualization assist? CS 7450

3. Basic Premise • Understanding (the cognitive aspects) is the crucial part of InfoVis • Visualization is simply a tool useful for aiding comprehension and understanding • Discussed the role of external cognition aids briefly last time CS 7450

4. How Are Graphics Used? • What does a visualization or graphic image provide for us? CS 7450

5. How Are Graphics Used? • Larkin & Simon ‘87 investigated usefulness of graphical displays • Graphical visualization could support more efficient task performance by: • Allowing substitution of rapid perceptual influences for difficult logical inferences • Reducing search for information required for task completion • Sometimes text is better CS 7450

6. Cognitive Map • What is it? CS 7450

7. Understanding • People utilize an internal model that is generated based on what is observed • Tversky calls the internal model a cognitive map • Think about that term CS 7450

8. Example • You’re taking the MARTA train to get to Georgia State University • You have some existing internal model of the system, stops, how to get there • On train, you glance at MARTA map for help • Refines your internal model, clarifying items and extending it • Note that it’s still not perfect, no internal model ever is CS 7450

9. Cognitive Map • Just don’t have one big one • Have large number of these for all different kinds of things • Collection of cognitive maps --> Cognitive collage CS 7450

10. 1. Process Models • (Recall the user and cognitive models from HCI?) • Process by which a person looks at a graphic and makes some use of it • A number of substeps probably exist • Can you describe process? CS 7450

11. Process Model 1 • Spence • Navigation - Creation and interpretation of an internal mental model CS 7450

12. Navigation Content Model Browse Browsingstrategy Internalmodel Formulate abrowsingstrategy Interpret Interpretation CS 7450

13. Interpretation • Can someone explain that? CS 7450

14. Interpretation • Content is the display on screen. Modeling of that pattern results in cognitive map. Interpretation (ah, variables x and y are related) leads to new view, that generates an idea for a new browsing strategy. Look at the display again with that. CS 7450

15. Process Model 2 • Card, Mackinlay, Shneiderman book • Knowledge crystallization task • Gather info for some purpose, make sense of it by constructing a representational framework, and package it into a form for communication or action CS 7450

16. Knowledge Crystallization • Information foraging • Search for schema (representation) • Instantiate schema • Problem solve to trade off features • Search for a new schema that reduces problem to a simple trade-off • Package the patterns found in some output product From CMS ‘98 CS 7450

17. How Vis Amplifies Cognition • Increasing memory and processing resources available • Reducing search for information • Enhancing the recognition of patterns • Enabling perceptual inference operations • Using perceptual attention mechanisms for monitoring • Encoding info in a manipulable medium CS 7450

18. Process task Raw data Data tables Visual Structures Views Data transformations Visual mappings View transformations CS 7450

19. Knowledge Crystallization Overview Zoom Filter Details-on-demand Browse Search query Task ExtractCompose Author,decideor act Foragefor data Search forschema Problem-solve Reorder Cluster Class Average Promote Detect pattern Abstract Instantiateschema Read fact Read comparison Read pattern Manipulate Create Delete Instantiate CS 7450

20. Intermission • Popcorn & sodas for everyone! • Admin stuff • Circulate photos • Anyone need an info form yet? CS 7450

21. 2. User Tasks • What things will people want to accomplish using information visualizations? • Last time, we discussed • search vs. browsing CS 7450

22. Browsing vs. Search • Important difference in activities • Appears that information visualization may have more to offer to browsing • But…browsing is a softer, fuzzier activity • So, how do we articulate utility? • Maybe describe when it’s useful • When is browsing useful? CS 7450

23. Browsing • Useful when • Good underlying structure so that items close to one another can be inferred to be similar • Users are unfamiliar with collection contents • Users have limited understanding of how system is organized and prefer less cognitively loaded method of exploration • Users have difficulty verbalizing underlying information need • Information is easier to recognize than describe Lin ‘97 CS 7450

24. Thought • Maybe infovis isn’t about answering questions or solving problems… hmmm • Maybe it’s about asking better questions CS 7450

25. Tasks • OK, but browsing and search are very high level • Let’s be more specific… CS 7450

26. Example from Last Time Which state has the highest income? Is there a relationship between income and education? Are there any outliers? Questions: CS 7450 Example courtesyof Chris North

27. Exercise • What are the (types of) tasks being done here? • Can you think of others? • Let’s develop a list CS 7450

28. Task Taxonomies • Number of different ones exist, important to understand what process they focus on • Creating an artifact • Human tasks • Tasks using visualization system • ... CS 7450

29. Shneiderman • What’s his mantra? • Overview first, then zoom & filter, then details on demand • Overview first, then zoom & filter, then details on demand • Overview first, then zoom & filter, then details on demand • Overview first, then zoom & filter, then details on demand • … VL ‘96 CS 7450

30. Elaborated More • Task set? • Overview • Zoom • Filter • Details on demand • Relate • History • Extract • Are these end-user tasks? CS 7450

31. User Tasks • Wehrend & Lewis created a low-level, domain independent taxonomy of user tasks in visualization environments • Eleven basic actions • identify, locate, distinguish, categorize, cluster, distribution, rank, compare within relations, compare between relations, associate, correlate Vis ‘90 CS 7450

32. W&L 1 • Locate • Finding something that one knows about already CS 7450

33. W&L 2 • Identify • Describe an object not necessarily known previously CS 7450

34. W&L 3 • Distinguish • Detecting different values of same variable CS 7450

35. W&L 4 • Categorize • Define divisions that visual objects can be sorted by CS 7450

36. W&L 5 • Cluster • Determining whether data items are clustered or not CS 7450

37. W&L 6 • Distribution • Describe overall pattern of data CS 7450

38. W&L 7 • Rank • Finding best and worst, for example CS 7450

39. W&L 8 • Compare within entities • Decide something based on attributes of similar objects CS 7450

40. W&L 9 • Compare between relations • Different or sets of entities used as basis of comparison CS 7450

41. W&L 10 • Associate • Form relationship between objects on display CS 7450

42. W&L 11 • Correlate • Determine which objects share similar attributes CS 7450

43. Another Taxonomy • Zhou and Feiner • More for multimedia explanation than for infovis, but still useful to us CHI ‘98 CS 7450

44. Visual Task Taxonomy • Zhou and Feiner developed a hierarchical taxonomy/model of visual tasks Correlate -- Plot -- MarkCompose Distinguish -- MarkDistribue -- Isolate Emphasize -- Focus -- Isolate -- Reinforce Generalize -- Merge Identify -- Name -- Portray -- Individualize -- Profile Locate -- Position -- Situate -- Pinpoint -- Outline Rank -- Time Reveal -- Expose -- Itemize -- Specify -- Separate Switch # Direct visual # organizing and # encoding tasks Encode -- Label -- Symbolize -- -- Quantify -- -- Iconify -- Portray -- Tabulate -- Plot -- Structure -- Trace -- Map # Relational tasks Associate -- Collocate -- Connect -- Unite -- Attach Background Categorize -- MarkDistribute Cluster -- Outline -- Individualize Compare -- Differentiate -- Intersect CS 7450

45. Interpretation • The nested items are refinements of particular ways of achieving task • E.g., To locate an item, we might use the more specific visual task pinpoint CS 7450

46. Dimensions • Visual tasks have two main dimensions • 1. Visual accomplishments - describe presentation intents that task might help to achieve • 2. Visual implications - particular type of visual action that visual task may carry out CS 7450

47. 1. Visual Accomplishments • All about presentation intent • Classified into two categories: • Tasks that inform the user (e.g., make a presentation with ppt) • Tasks that enable user to explore or compute (e.g., decide which stock to buy) • Each of these can be broken down further CS 7450

48. Visual Accomplishments Inform Enable Elaborate Summarize Explore Compute Associate Background Categorize Cluster Compare Correlate Distinguish Generalize Identify Locate Rank Emphasize Reveal Search Verify Sum Differentiate Categorize Cluster Compare Correlate Distinguish Emphasize Identify Locate Rank Reveal Categorize Compare Correlate Distinguish Identify Locate Rank Reveal Correlate Locate Rank Correlate Locate Rank CS 7450

49. 2. Visual Implications • Categorize various visual tasks by whether they imply • Certain types of visual organization • Certain ways of visual signaling • Certain paths of visual transformation CS 7450

50. Making InfoVis More Task-Focused • InfoVis • Representational Primacy • Show the data truthfully in meaningful ways • Analytic Primacy • Support user analysis and tasks Amar & Stasko InfoVis ‘04 CS 7450