Human-Computer Interaction - user’s knowledge structure -

1. Human-Computer Interaction- user’s knowledge structure - Prof. dr. Matthias Rauterberg Faculty of Technology Management Technical University Eindhoven The Netherlands

2. The fundamental design problem designer’s mental model user’s mental model perceived semantic intended semantic perceivable user interface forms implemented functions

3. What is Human-Computer Interaction about? Working domain Goal: Actual Performance => Desired Performance Working system user system

4. Three different function types Secondary functions [dialog manager] Tertiary functions [dialog manager] Primary functions [application manager] Application object(s)

5. The User Interface (1) user action perception input/output interface presentation dialog module dialog dialog dialog state objects functions application application module state application transformation application objects functions user interface

6. learning Long-term memory module goal problem Short-term memory user solving module expectation plan motor perception module action memory module visual auditory tactile operation "memory" "memory" "memory" tactile output input visual output auditory output user interface input-handler output-handler output-handler presentation dialog dialog dialog state objects (DO) functions system dialog module application state application application transformation objects (AO) funcrtions application module The User Interface (2) [further reading]

7. Several Notions of ‘Models’[Horst Oberquelle, 1984]

8. User’s Mental Models[Stephan Dutke: Mental Models-constructs of knowledge and understanding, 1994] Model: Interface elements external stimuli e.g. visual system perception mental structure cognition e.g. Action Cycle e.g. Fitts Law action

9. The Difference between Internal and External Memory • the mental model of the user about the external world is always incomplete • all necessary information which is not in the internal memory must be provided by the environment (the “external memory”)

10. Knowledge in the World and in the Head

11. User’s motor behavior: Fitts' Law T = k log2(D/S + 0.5) with k ~ 100 msec T = time to move the hand to a target D = distance between hand and target S = size of target Fitts' Law is a model to account for the time it takes to point at something, based on the size and distance of the target object. Fitts' Law and variations of it are used to model the time it takes to use a mouse and other input devices to click on objects on a screen. Fitts' Law can be applied by designers to suggest moving target buttons closer and making them larger for extremely commonly used buttons. In detail, applying the formula can be extremely useful for exact design of time-critical applications.

12. The Visual Perception System

13. Activity Theory: the Complete Action Cycle task(s) goal-, subgoal-setting planning of execution feedback control of selection of means action mental operation physical operation

14. User’s model: activity cycle task description cognitive process Cognitive level feedback Feedback level goal instanciation Goal instanciation level observable action Action level [further reading]

15. User’s mental structure Regulation-driven goal setting Cognitive level System level Goal instanciation level Feedback level [further reading] Action level 1 i h F_10 G_2 M_3 h F_3 Main menu MsDOS Start menu Main menu F-file

16. How to investigate the user’s mental model?

17. User’s learning process We (1996) found a negative correlation between Behavioral-Complexity and Mental-Complexity [further reading]

18. mental activity is like the ‘flow of a river’

19. Learning means ‘digging’ learning process [further reading]

20. User’s Behavior: an example "dales" of knowledge about successful behavior s0 "wall" of knowledge h d about unsuccessful behavior s1 CR b F9 F2 s2 s3 F3 TAB _

21. User’s real knowledge structure knowledge about unsuccessful behavior knowledge about successful behavior

22. Thank you for your attention More at my homepage