phd-defense
DESCRIPTION
slides used for my PhD defense 'Maps, how do users see them?' December 2012TRANSCRIPT
Maps, how do users see them?
Kristien OomsDepartment of Geography – Ghent University
An in depth investigation of the map users’ cognitive processes
Maps, how do users see them?
Improve the effectiveness of (screen) map designs based on the users’ characteristics.
After Kolácný (1969)
Purpose of maps Communication
Maps, how do users see them?
Contribute to the understanding of how map users read, interpret, store, and use the presented visual information on screen
maps.
AttentionRead
Store
Use
Understand
InfluenceImprovedesign
Retrieve
Interpret
Maps, how do users see them?
Contribute to the understanding of how map users read, interpret, store, and use the presented visual information on screen
maps.
After van Elzakker and Wealands (2007)
Maps, how do users see them?
Investigate the influence of (cartographic) expertise on the map users’ cognitive processes and their limitations while
processing the visual information presented on screen maps.
After van Elzakker and Wealands (2007)
After Kolácný (1969)
Maps, how do users see them?
• Research Questions1. How do map users read and interpret the visual
information presented on screen maps?
2. How do map users store and retrieve (use) the information that was previously gathered from screen maps?
3. How are the map users’ cognitive processes influenced by deviations in the map image?
4. How does (cartographic) expertise influence the cognitive processes investigated in the previous research questions?
Maps, how do users see them?
Ch 5-6: Complex Map Design
Ch 7: General Discussion
Ch 8: General Conclusion
Ch 5: Ch 6:
eye tracking
thinking aloud
sketch map
RQ 2
RQ 4
RQ 1 RQ 3expert
novice
questionnaire
Ch 1: Introduction
Ch 2-4: Basic Map Design
RQ 2
Ch 2: Ch 3: Ch 4:
RQ 4
RQ 1 RQ 3expert
novice
eye tracking
questionnaire
reaction times
Part I - Basic Map Design
• Task:– Visual search
• Techniques:– Eye tracking– Reaction times– Questionnaire
• Analyses:– Statistical– Visual
Part I - Basic Map Design
• Eye tracking?
...
Part I - Basic Map Design
• Eye tracking?• Fixations:
Insights in...- Attentive behaviour- Interpretation- Cognitive processes
Metrics:- Location of the
fixations- Fixation duration- Number of fixations
• Saccades:
Part I - Basic Map Design
• Reaction time measurements?– Time needed to locate label– Recorded through button actions– Time intervals are compared
• Questionnaires?– Background information!
• User characteristics• Familiarity with stimuli• Feedback
Part I – Experts vs. novices
• Aims:– Study cognitive processes– Difference experts vs. novices?– Explain by Cognitive Load Theory
• Structure WM: limited Cognitive load• Influence of map design
– Content– Symbolisation
• Room for learning
Chapter 2
Chapter 2
Part I – Experts vs. novices
• Results: ‘experts’ vs. ‘novices’
– Reaction time measurements• Experts vs. novices• Before vs. after
Chapter 2
Part I – Experts vs. novices
• Results: ‘experts’ vs. ‘novices’
Fixation duration (s)
Fixation count (fix/s)
Chapter 2
Part I – Experts vs. novices
• Results:– Fixation distribution
Low number of fixations
High number of fixations
Part I – Experts vs. novices
• Conclusion– Similar trend in both user groups: CLT– Experts significantly faster at locating the names – Explained by eye movement metrics
Shorter fixations
More fixations per second
Locates the names faster
Can interpret a larger part of the map in the same amount of time
Interprets map more efficiently
Can interpret the map’s content more efficiently
Chapter 2
Chapter 3
Part I – Visual Analytics
• Aims:– Extend statistical analyses
• Maps: communicate spatial information• Study spatial dimension• Influence of map layout
– Visual Analytics Toolkit• Filter data: time & attributes• Aggregate data
1 participant | 10 seconds
Part I – Visual Analytics
• Time series• Aggregation• Simplification• Selection
Chapter 3
Part I – Visual Analytics
• Conclusion– Selection, aggregation, simplifation
• Tools are indispensable
– Patterns: search behaviour• Time series: evolution search behaviour• Influence of map layout (labels)• Individual differences
Chapter 3
Chapter 4
Part I – Efficient and effective labels?
• Aims:– Evaluate different map designs
• Label placement algorithm– Improved efficiency faster– Lower map quality?
– Influence on (novice) users?• Effectiveness of the map?
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Chapter 4
Part I – Efficient and effective labels?
• Results: ‘border’ vs. ‘total’
– Reaction time measurements
– Eye movements• Fixation duration• Fixation count• Visualisation scanpaths
– Questionnaires
Part I – Efficient and effective labels?
• Conclusion– Improved (algorithmic) efficiency
– No influence on effectiveness• Consiously: user statements
– “no difference was seen”
• Unconsiously: measurements– No deviations in
» Reaction time measurements» Eye movement metrics
Chapter 4
Part II – Complex Map Design
• Task:– Study & draw
• Techniques:– Eye tracking– Thinking aloud– Sketch maps– Questionnaire
• Analyses:– Statistical– Visual
Part II – Complex Map Design
• Aims:– Communication process:
– Expertise?– Influence of deviations
SensoryInput
WorkingMemory
TransferredLong Term
Memory
Transferred
Retrieved
Virtually unlimited
Limited in -size -time (debate)
Using links, pointers with previous knowledge
Part II – Reading and Interpretation
• Eye movement:– Metrics
• Average fixation duration:Experts significantly shorter
• Number of fixations per secondExperts significantly more
Confirm previous findings
Chapter 5
Part II – Reading and Interpretation
• Eye movements– Gridded visualisations
• Fixation count• Total dwell time• Average fixation duration
• Average per user group• Maximum per user group
Chapter 5
Part II – Reading and Interpretation
• Eye movements– 2D gridded visualisations
Average fixation count
Maximum fixation count
Chapter 5
Part II – Reading and Interpretation
• Eye movements– 3D gridded visualisation
Average total dwell time
Average fixation duration
Chapter 5
Part II – Reading and Interpretation
• Eye movements– Gridded visualisation: statistical
comparisonStatistical comparison (ANOVA)
Chapter 5
Part II – Reading and Interpretation
• Eye movements– Scanpaths
Chapter 5
Part II – Reading and Interpretation
• Eye movements– Conclusion
• Focus on general structuring elements• Fixate more on top and left side
– Experts: more pronounced
• Influence of deviations– No influence for less important elements– Confusion for structuring elements
» Colour water bodies» Mirrored map elements
– Novices: more pronounced
Chapter 5
Chapter 6
Part II – Cognition and Memory
• Thinking aloud?– Say out loud every thought– Audio & video recordings– Insights in...
• Working Memory– How is information stored– How much information
• Information retrieval– Links with Long Term Memory
Square...rectangle...euhm...house? ..what do you guys
think?
Chapter 6
Part II – Cognition and Memory
• Thinking aloud– Recordings– Transcriptions– Segmentation
• Words– Word count
• Full thought (sentences)– Protocol analyses
Part II – Cognition and Memory
• Thinking aloudChapter 6
Part II – Cognition and Memory
• Thinking aloud– Word segmentation (count in ‰)
Based on theme Based on frequency
Chapter 6
Chapter 6
Part II – Cognition and Memory
• Thinking aloud– ‘Full thought’
• 4 Levels of codes:Level 1: Map Level
Orientate – Execute - EvaluateLevel 2: Item Level
Gather Thougts – Draw – Correct - EvaluateLevel 3: Confidence
Confident – Neutral – Not ConfidentLevel 4: Actions
Check – Correct – Draw – Erase – Fill Colour – Talk – Take Pencil
• Time ratio for each code: [0-1]
PsychologicalTheories
Task Analysis
Psychological Model
Proposed Codes
CodingScheme
Segmented Protocols
Transcriptions(Raw Protocols)
Coded Protocols
T H E O R Y
USERDATA
Part II – Cognition and Memory
• Sketch maps?– Draw map from memory– Paper & pencil– Insights in...
• What is remembered– Shape, location, relations, ...
• How much is remembered• Importance of objects
– Order of drawing
Chapter 6
Part II – Cognition and Memory
• Sketch mapsChapter 6
Part II – Cognition and Memory
• Sketch maps– Order of drawing
– Scores on maps
• Questionnaire– Stated confidence
Chapter 6
Part II – Cognition and Memory
• Conclusion– General structures: similar
• Novices: store more information– Descriptions, locations, etc.– No extra knowledge– Not derive extra information
• Experts: can retrieve more information– Know objects’ names – Background information
» Derive information– Larger chunks in WM
Chapter 6
General Conclusion1. How do map users read and interpret the visual
information presented on screen maps?• Guided by main structuring map elements• Influence on cognitive load Experts: more efficient interpretation
2. How do map users store and retrieve (use) the information that was previously gathered from screen maps?
• Limited information in WM• Retrieve information from LTM through links (chunking) Important influence of background knowledge (carto & geo)
3. How are the map users’ cognitive processes influenced by deviations in the map image?
• Subtle differences: almost no influence• Deviations to main structures (mirror, colour): confusion Novices are most influenced
4. How does (cartographic) expertise influence the cognitive processes investigated in the previous research questions?
General Conclusion
• Effective screen map design?– Guide attentive behaviour
• Reference frame: clearly visible• Other elements: neutral
– Structure/organise information• Group objects, e.g. through colour use
– Optimal map?• Less essential for non-structuring elements• Important for structuring elements
More [email protected]
1. Ooms, K., De Maeyer, P., Fack, V., Van Assche, E., & Witlox, F. (2012). Interpreting maps through the eyes of expert and novice users. International Journal of Geographical Information Science, 26 (10), 1773-1788.
2. Ooms, K., Andrienko, G., Andrienko, N., De Maeyer, P., & Fack, V. (2012). Analysing the spatial dimension of eye movement data using a visual analytic approach. Expert Systems with Applications, 39(1), 1324-1332.
3. Ooms, K., De Maeyer, P., Fack, V., Van Assche, E., & Witlox, F. (2012). Investigation the effectiveness of an efficient label placement method using eye movement data. The Cartographic Journal, 49(3), 234-246.
4. Ooms, K., De Maeyer, P., & Fack, V. (under revision). Understanding expert and novice map users: Reading and interpretation. Cartography and Geographic Information Science.
5. Ooms, K., De Maeyer, P., & Fack, V. (under revision). Listen to the map user: Cognition, memory, and expertise. The Cartographic Journal.
Thank you for your attention!
Questions?