1. Modelling interactions:
digital and physical
Alan Dix
https://www.alandix.com/academic/talks/ICTCS-School-2021/


ICTAC 2021

2. 
Part I – lightning tour
kinds of model
gaps and challenges


ICTAC 2021

3. what to model
users
– cognitive models
– task models
system
– behaviour
– architectural structure
world
– domain models


4. what to model
users
– cognitive models
– task models
system
– behaviour
– architectural structure
world
– domain models


5. types of system model
• dialogue – main modes
• full state definition
specific
system

6. example: car clock
three buttons:
mode – cycles between hours, mins, seconds
+/– – increments/decrements selected item
we will define state and actions
N.B. will not be right first time ... spot the mistakes ...
16:55:00
mode – +

7. clock state
state
hours: Nat, mins: Nat, secs: Nat – all just numbers
selected: { ‘NONE’, ‘HRS’, ‘MINS’, ‘SECS’ }
hours < 24 ∧ mins < 60 ∧ secs < 60
initial state
hours = 0, mins = 0, secs= 0
selected = ‘NONE’
display
hours “:” mins “:” secs (with selected flashing)

8. clock actions …
increment (+)
if ( selected = ‘NONE’ ) do nothing
if ( selected = ‘HRS’ )
if ( hours < 23 ) hours’ = hours+1
if ( hours = 23 ) hours’ = 0
if ( selected = ‘MINS’ )
if ( mins< 59 ) mins’ = mins+1
if ( mins= 59 ) mins’ = 0
...

9. types of system model
• dialogue – main modes
• full state definition
• abstract interaction model
specific
system
generic
issues

10. PIE model – abstract properties
predict
e.g. predictability:

11. undo

12. more complex undo – the cube

13. PIE model – abstract properties
predict
e.g. predictability:

14. common domains for formal methods
aerospace
nuclear
other areas?
need
cheaper/easier
techniques
safety critical
high investment

16. Chapter 3:
Trends and Gaps
not just keystrokes
and mouse-clicks

17. HCI trends: formal challenges
changing user interaction
– choice and ubiquity, diverse people, diverse devices
and contexts, physicality and embodiment, really
invisible, experience and values, social and personal
use, notification-based interaction, basic HCI
changing technology
– vast assemblies, big data, autonomy and complexity
changing design and development
– maker/hacker culture and mass customization, agile
and test-driven development

18. formalising interaction: challenges
what – actors and entities
– people, physical objects, space, information
what – levels of abstraction
– granularity, continuity and time, level of generality,
syntax vs semantics
who and when (and why?)
– reducing formal expertise, reducing effort, increasing
benefit
how
– types of reasoning, knowledge rich reasoning,
flexible levels of detail, multiple notations, generic
descriptions and standards

19. today
• domains – not nuclear!
• physical as well as digital
• granularity – not just dialogue
• flexible level of detail
• method users – no Maths degree

20. exercise
choose something physical
e.g. book, phone, scissors
if digital assume battery dead.
model it formally (-ish) … or whatever works!
– What it’s like
– What you can do with it
– How it fits with other things
Image Mark Turnauckas: https://www.flickr.com/photos/marktee/5590077419