- Cognitive engineering and user-centered design aim to make interfaces intuitive based on how the human mind works. This includes task analysis, conceptual models, and usability testing. - Early approaches viewed the user's mind as a computer that an interface could transmit information to and from smoothly. Later, the focus shifted to fulfilling user needs rather than system needs. - Methods like GOMS models, card sorting, and heuristic evaluation help identify usability issues based on how users perceive and interact with systems. - Testing involves observing users completing tasks while thinking aloud to understand problems and gather feedback for improving designs.

1. Cognitive Engineering and
User Centered Design
Frederick van Amstel @fredvanamstel
Architecture and Design School - PUCPR
www.fredvanamstel.com

2. Expansion of the design object
• Graphic Design
• Industrial Design
• Information
Architecture
• Information Design
• Interface Design
• Interaction Design
• User Experience
Design
1980: complex entity 1990: emergent performance

3. Expansion of the design object
Model 302 Palm VX
1980: complex entity 1990: emergent performance

4. The user became the anchor to the
immaterial design object.

5. Second order design:
designing systems to indirectly design user behavior.

6. HCI as Cognitive Science
• The user’s mind works
much like a computer
• The interface should
transmit information
smoothly from the user to
the computer and vice-
versa
• The interface is limited by
the cognitive capacity of
the user

7. The Human Processor Model (Card, 1981)

8. GOMS Model
• Goals, Operators, Methods, and Selection rules
• This model can be used to predict how much time
a typical interaction with the computer will take
• Based on the average time people took to perform
basic operations in laboratory tests
• An interface can be broken down into operations
(such as mouse click, mouse movement and
keystroke) and compared against another interface

9. GOMS model applied to
making bold text with a
combination of mouse +
keyboard.
0.5s
0.1s
0.3s
0.3s
0.2s
0.4s
Total 2.3s

10. GOMS model applied to making bold text with mouse only.
0.5s
0.8s
0.3s 0.2s 0.3s
Total 3.4s

11. Task analysis
• Breaking down actions into the meaningful steps
required to reach a specified goal
• Efficiency can be measured by execution time and
error rates (wrong steps)
• Steps may be considered unnecessary, misleading
or workflow bottlenecks
• Task analysis can be used both for requirements
gathering and system evaluation

12. Hierarchical Task Analysis (Gagne, 1962).

13. CTT - ConcurTaskTree

14. Use of task models in the design cycle (Paternò et al, 2013).

15. Informal task analysis is better suited for Collaborative and
Participatory Design.

16. Formal task analysis is suited for critical and highly complex
systems such as Air Traffic Control (Model Checking).

17. HCI as Engineering
• The interface should fulfill
user needs, not system
needs
• The interface is a design
object on its own that
requires specialists in
cognition who can predict
the user behavior

18. Conceptual Models (Norman, 1986)
Designer User
Designer Model User’s Model
System
System Image

19. When a person used to drive manual cars tries out an automatic
transmission car, the mental model generates errors.

20. Card-sorting
• Method for classifying and organizing information
according to the user’s mental model
• Can be used to test or to generate classifications
• Each card represents an information "chunk"
• The process consists of grouping similar cards and
labelling the groups

21. Card-sorting sessions for the UFPR.br website redesign.
Offline Online

22. Bottom-up hierarchies based on the frequency of associated
cards (Dendogram).

23. Exercise
• Run an open card sorting experiment with the
English version of PUCPR’s website http://
en.pucpr.br
•PUCPR's campuses
•About Curitiba
•About Brazil
•What is like to study at
PUCPR
•Administration
•Words from the Rector
•Contact form
•Art, Culture, Sport and
Leisure activities
•Community project
•Internationalization
agents
•English Semester
Program
•International students
•Interships
•Partnerships
•Portuguese as Second
Language course
•Information for
Prospective Students
•PUCPR Exchange
Programs
•PUCPR International
Staff
•Scholarships
•Special programs
•PUC Innovation Agency
•Research areas at
PUCPR
•Technopark
•Undergraduate Research
•Central library
•Clinics
•Communication Center
•Gralha Azul
Experimental Farm
•Hospitals
•Laboratories
•Language Center
•Veterinarian Hospitals
•Graduate programs
•Undergraduate Programs

24. Cognitive Walkthrough: what a novice user would think and do
in this particular situation? (Wharton, 1994)

25. Seven stages of action (Norman, 1986)
Goals
Intention
Action specification
Execution
Evaluation
Interpretation
Perception
System

26. Design questions based on seven stages of action
(Norman, 1988)
Does this do what I want to do?
Which actions are possible?
Which steps are necessary?
How to execute the step?
Am I in the desired state?
In which step am I?
What is the system state?
System

27. Exercise
• Look at the strange object in front of you and try
to guess what is used for
• Sketch all the uses you can find for it while
representing how to handle the object

28. Knowledge in the head: how do I open these doors?
(Norman, 1988)

29. Knowledge in the world: door handles tells you how to open the
door (Norman, 1988).

30. Knowledge in the world: door handles tells you how to open the
door (Norman, 1988).

31. Knowledge in the world: door handles tells you how to open the
door (Norman, 1988).

32. Affordances in Graphic User Interfaces
(Norman, 1988; Eaton, 2002).

33. Breakdowns in interactions (different than expected outcomes)
may stimulate learning (Winograd e Flores, 1987).

34. Learning curve: learnability X mastery. Photoshop is harder to
learn, affords many breakdowns but still the user can do more.
0
22,5
45
67,5
90
1 week 2 weeks 3 weeks 4 weeks
Adobe Photoshop
Corel Photopaint
percentage of
functions used

35. Human memory X Computer memory
Selective Unselective
Evolutive Stable
Associative Discrete

36. Cognitive Analysis
• Method to estimate the learning process required
to interact with a particular interface based on the
concepts of affordances, memory and breakdown
• Can be applied to evaluate prototypes or finished
interfaces
(Van Amstel, 2010)

37. Questions
What does the user
needs to know?
What does the
interface explains?
Affordances
What does the user
needs to remember?
What does the
interface recall?
Memory
What does the user
needs to discover?
What does the
interface proposes?
Breakdown

38. Exercise
• Apply the Cognitive Analysis method on the Menor
Preço mobile app, specifically, in the search for
good prices with the map interface
• Organize your findings in a table with the
questions at the top

39. Heuristic Evaluation
• Expert evaluation based on standardized usability
principles or idiosyncratic experience
• The expert look for usability problems (or good
solutions) in the interface and related them to the
heuristics. If she cannot find a proper heuristic, a
new heuristic may be created
• Problems are rated according to severity scales
(Nielsen and Molich, 1990)

40. Heuristics are rules of thumb generated by accumulated
professional experience (Martin, 2009).

41. Heuristic evaluation of my old radio using the 10 Usability
Heuristics of Nielsen (1995).
Big snooze button makes it easier
to touch when partially asleep
(Heuristic 7 - Shortcuts)
The Auto button turn on the radio when the
alarm goes on, but this is not clear from this
label. (Heuristic 2 - Familiar language)

42. Exercise
• Identify Usability Problems in home appliances,
write them down on a sheet of paper and relate
them to the 10 Usability Heuristics of Nielsen
1.Visibility of system status
2.Match between system and the real world
3.User control and freedom
4.Consistency and standards
5.Error prevention
6.Recognition rather than recall
7.Flexibility and efficiency of use
8.Aesthetic and minimalist design
9.Help users recognize, diagnose, and recover from errors
10.Help and documentation

43. Usability Testing
• Method to find problems understand better the
user interaction
• Users carry out pre-defined or user-defined tasks
with the interface while a facilitator asks questions
and remind users about the think aloud protocol
• Can be used to evaluate an interface, collect user
feedback and compare against competitors

44. Usability Lab

45. Eye-tracking
Tobii
Monitor Attention heatmaps
Gaze paths

46. Analysis of usability data with Morae (screen recording, camera,
keystrokes, mouse clicks, task completion).

47. Proportion of usability problems found versus the number of test
participants (Nielsen and Landauer, 1993).
● test subject
○ heuristic evaluator

48. Current types of usability testing.

49. Controlled experiments with alternative web page designs.

50. Amazon composed its old interface based on A/B testing. The
user experience was quite fragmented. Amazon gave up on this.

51. User modeling and adaptive systems (Brusilovski, 1996).

52. Adaptive menus in Microsoft Office 2000.

53. User profiling with Facebook newsfeed and beyond — collateral
data and predicted behavior (Bakshy, 2012).

54. The Facebook Game of Hide and Seek (Van Amstel, 2015).

55. Cambridge Analytica's unethical user profiling in Facebook for
political campaigns.

56. Donald Norman admitted in 2015 that User Centered Design
could be harmful.

57. Cognitive Engineering
limitations
• Too much focus on the mind and little on the
body
• Recent studies considers also emotion, but in
very shallow understanding of it
• Individualistic theory with a weak ethical
stance
• Can easily turn into "Social Engineering"

58. Thank you!
Frederick van Amstel @fredvanamstel
Architecture and Design School - PUCPR
www.fredvanamstel.com