1. Image and interface Pertti Saariluoma University of Helsinki

2. Visualization and mind Visualization makes difficultly perceivable things conceivable by making required information visible Ability to see the essence of the message Ability to represent all necessary details Suggestions from the below Visualization is an interaction process between interface and image in mind

3. Subgoals for visualization Organising interaction in visualization has several subgoals Identification, localization, categorization. clustering, ordering, comparing associating Data transformation: abstraction, magnifying, minimizing, speeding up, slowing, looking through, and constructing

4. Challenges for visualization The power of visualization is in making easier to comprehend complex issues Task analysis and cognitive processes Myth of perception What are the true psychological preconditions of various types of visualization situations?

5. Criterion of challenge The ultimate goal of visualization is to decrease number of human errors. Consequently, the ultimate challenge is to organise interaction as ergonomic as possible What kind of performance limits are associated to various types of cognitive processes?

6. Perceptual preconditions Perception and attention Perception = a coloured three dimensional space with moving objects Luminance, brightness, contrast, colour sensitivity depth cues, movement Attention – capacity and discrimination

7. Limits of memory Working memory capacity and modularity Chunking ----------------------------------------------- EasyDifficult XX X XX X XX X X XX X

8. Modularity and skill What is modularity? Visuospatial and articulatory Long term working memory and skill Training users and transfer Memory load by main task and secondary tasks: Navigation capacity explainable errors

9. Apperception and error All errors are not caused by capacity limits Content-errors are not explainable by limited capacity but by incorrect presuppositions Perceiving non-perceivable Interpretation

11. From perception to apperception Do we perceive representations? Atom, infinity, eternal, possible Representations are constructed of conceptual information, which is used to interpret perceptual environment How to incorporate conceptual knowledge to visualizations?

12. Symbolic and functional Symbols in visualizations have semiotic functions (red for a high termperature and crises) What is functional or sense-making? Wholes as ’meaningful’ combinations of objects Why some whole has the elements it has? How to visualize functional structures?

13. Interaction and construction The functional organisation of human representations put forward a number of challenges What kind of constructive tools? What is relevant? An example of dimensionality and conceptual compression

14. Effective visualization All knowledge that is needed in interaction but no more Conceptual clarity Effective tools Clear understanding of the limits of the tools and the tacit presuppositions