1. Chapter 5 – Cognitive Engineering
HCI: Developing Effective Organizational Information Systems
Dov Te’eni
Jane Carey
Ping Zhang

2. A Simplified View of Human Information Processing (HIP)
Figure 5.3 presents a simplified model of Human Information Processing which includes processors and memories that interact in order to process information.
There are three types of processors:
Perceptual,
Cognitive, and
Motor processors.
Two types of memory:
Working memory
Long-term memory
Copyright 2006 John Wiley & Sons, Inc

3. A Simplified View of Human Information Processing (HIP)
Figure 5.3 A simplified model of Human Information Processing (HIP),
including memories and processor.
Copyright 2006 John Wiley & Sons, Inc

4. A Simplified View of Human Information Processing (HIP)
Ultimately, interested in the
speed and accuracy of the
task completion
Figure 5.3 A simplified model of Human Information Processing (HIP),
including memories and processor.
Copyright 2006 John Wiley & Sons, Inc

5. Gulfs of Execution and Evaluation
derive the relationship between mental intentions & interpretations and physical actions & states
Gulf of execution: the gap between what you intend to do and the allowable actions (can user figure out what to do?)
do system actions match user intentions?
Is it clear what to do to achieve a goal?
Gulf of evaluation: the gap between the ease of perceiving the state by the user to see if their goal/intentions were met (can user tell if they were effective?)
does system provide information about it’s state?
is this easy to observe and interpret?
Copyright 2006 John Wiley & Sons, Inc

6. Bridging the gaps using Norman’s Model
Establish a goal that needs to be accomplished.
Form the intention (or hierarchy of intentions) that will accomplish the goal.
Specify the action sequence to implement the intentions.
Execute the action.
Perceive the state of system resulting from the action.
Interpret the system state.
Evaluate your interpretation against the expectation based on your intentions.
Figure 5.6 Norman's seven stage model of
user activity
Copyright 2006 John Wiley & Sons, Inc

7. Copyright 2006 John Wiley & Sons, Inc
Fit and Complexity
The fit between the user’s mental model of the system and the actual model of the system affects complexity, too. The greater the fit, the easier it is to determine how to translate goals into action. The greater the misfit, the more difficult and more erroneous is the process of bridging the execution and evaluation gulfs.
Copyright 2006 John Wiley & Sons, Inc

8. The GOMS Model for Describing HCI
GOMS: Goals, Operators, Methods, and Selection rules are the elements of a model that describes purposeful HCI.
Goals specify what the user wants and intends to achieve.
Operators are the elementary actions user executes
Methods are (frequently executed) sequence of operators or subgoals designed to accomplish goals.
Selection rules predict which method will be used. For example, “If the mouse is working, select ‘point to an item on screen’, if not select ‘choose OPEN option in file menu’”.
Copyright 2006 John Wiley & Sons, Inc

9. Copyright 2006 John Wiley & Sons, Inc
Using GOMS
Figure 5.9 A flow chart for building GOMS
Copyright 2006 John Wiley & Sons, Inc

10. Comparing Operating Systems
PC-Dos Method
Delete a file
recall that command word is ‘erase’
think of directory name and file name, retain as filespec
enter & execute command
return with goal accomplished
Mac Method
Delete a file
drag file to trash
return with goal accomplished
Mac uses fewer methods for same task –
Copyright 2006 John Wiley & Sons, Inc

11. Copyright 2006 John Wiley & Sons, Inc
Evaluation of GOMS
Advantages
precise estimations of cognitive effort
allows comparisons
identify particularly complex subprocesses
Disadvantages – No consideration of :
errors (designed to analyze basically error-free behavior of experts)
concurrency (parallel execution)
Copyright 2006 John Wiley & Sons, Inc