Cognitive Modeling for HCI

1
Cognitive Modeling for HCI

• David Crow
• david.crow_at_acm.org
• www.cs.cmu.edu/dccrow/

2
HF vs. HCI

• Human Factors
• discovers and applies information about human
  behavior, abilities, limitations and other
  characteristics to the design of tools, machines,
  systems, tasks, jobs and environments for save
  comfortable and effective human use (Sanders
  McCormick,1987, pp..5)
• Human-Computer Interaction
• is concerned with such issues as users
  capabilities and preferences and the degree to
  which interfaces support their activities.

3
Cognitive Modeling

• Is a form of theory
• Uses empirical results
• Develops analytical models that make quantitative
  predictions about a users performance

4
History

• Information processing concepts borrowed from
  computer science and engineering
• During WWII, complex military displays analyzed
  to improve their design
• Led to mathematical models of human behavior
  (Fitts Law, Hick-Hyman Law)

5
History (continued)

• Cognitive Psychology first described by Neisser
  in 1967
• Appearance of the journal of Cognitive Psychology
  in 1970
• The role of the environment

6
Applied Cognitive Psychology

• Carnegie Mellon University in the early to
  mid-1970s
• Moved to XeroxPARC
• Culminated in Card, Moran Newells (1983) The
  Psychology of Human-Computer Interaction

7
Psychology of HCI

• Theory-based, in the sense of articulating the
  mechanisms underlying the observed phenomena
• Hard Science
• Engineering theories of the user
• Task analysis, calculation and approximation

8
Cognitive Models

• Constrain the design space
• Estimate total task time
• Estimate training time and documentation
• Identify complex, error prone stages of the task

9
Model Human Processor

• An idealized information processing model of
  human perceptual, motor and cognitive systems
• Describes behavior using 3 processors, 4
  memories, 19 parameters and 10 principles of use

10
The GOMS Model

• a formal representation of routine cognitive
  skill
• a detailed description of knowledge required by
  an expert user to perform a specific task without
  error
• a usefully approximation of the processes
  underlying human behavior

11
GOMS

• Goals
• what the user wants to accomplish
• Operators
• the actions a user is able to take
• Methods
• well-learned subgoals and operators
• Selection rules
• guidelines for deciding between multiple methods

12
Why use cognitive models?

• It is useful to analyze the knowledge of how to
  do a task in terms of goals, operators, methods
  and selection rules. (John Kieras, 1996)
• Validated engineering models of human performance

13
Why use cognitive models? (continued)

• Provide a functional model of the task
• Specific information includes
• Tricks of the trade
• Perceptual skills
• Big picture

14
Where have cognitive models been used?

• Production systems, GLEAN (John Kieras, 1996),
  JIAA (Crow, 1998)
• Text editing (Card et al., 1983 John, 1996)
• Phone operators (Atwood, Gray, John, 1995)
• Video games (John, Vera, Newell, 1993)

15
How have cognitive models helped?

• Identification of potential errors
• Purchase of new workstations
• Prediction of learning time

16
Where does GOMS fit?

• Product Design is to develop a product that has
• Utility
• Usability
• Acceptance
• Salability
• Functional Level, Documentation, Keystroke
  Analyses

17
What GOMS is not!

• Usability Testing
• Interviewing technique
• Naturalistic observation
• Heuristic evaluation and other checklist
• Cognitive walkthroughs
• A design technique

18
Extensions

• New Input Devices
• Effects of fatigue and stress
• Individual differences
• Collaborative cognitive models